Custom Joinery, Cabinetmaking, Furniture Manufacturing, Kitchen Cabinet, Architectural Millwork and Wood Products HVAC Duct Engineering Guide

1. Why joinery and furniture ductwork is different from a sawmill

An Australian custom joinery, kitchen cabinetmaking, furniture manufacturing or architectural millwork facility is not a smaller sawmill. The processes are different. The dust is different. The chemicals are different. The space is different. And the regulatory frame is different. We see clients regularly walk into a duct quotation expecting the same numbers as a softwood mill, and the engineering reality is that joinery and furniture sit at a more demanding intersection of fine dust deflagration risk, solvent-finishing fire and toxicity risk, formaldehyde exposure from sheet-good substrates, and architectural-grade cleanliness requirements for the finished product.

The dust load per cubic metre of throughput is lower than a sawmill — a typical 800 square-metre joinery shop processes 15 to 40 cubic metres of board per week, against a sawmill that processes 2,000 to 8,000 cubic metres of log per day — but the fines content is higher and the particle size distribution shifts heavily toward the combustible fraction below 500 microns. A wide-belt sander on a melamine-faced MDF panel can generate dust with median particle size under 80 microns. The CNC router with 20,000 rpm spindle on a 12 mm hardwood plywood produces fines well below 500 microns at the cutter tip. The edge bander trim station throws a continuous stream of mixed PVC, ABS, melamine and adhesive chips. None of this is exotic, but all of it is combustible at workshop concentrations.

The chemical load is harsher than a sawmill. A modern furniture shop and most architectural millwork facilities apply 2K polyurethane topcoat — isocyanate hardener, polyol base, MEK solvent, polyurethane condensate. The kitchen cabinet sector has consolidated on UV-cured and water-based finishes for door and drawer-front production, but solvent-borne sealer, stain and topcoat remain widespread in the architectural and furniture segments. The paint mix room handles flammable Class 3 liquids under AS 1940 with vapour exposure governed by Safe Work Australia workplace exposure standards for toluene, xylene, MEK and isocyanate. The Safe Work Australia STEL for isocyanate is 0.005 ppm — sixty-six times tighter than the formaldehyde STEL — and there is no known safe respiratory exposure level. Capture must be complete.

The space is different. A joinery shop is rarely larger than 2,500 square metres under one roof, and many are 400 to 1,000 square metres in a tilt-up panel industrial unit. The HVAC duct runs are short — typical longest dust extraction main is 30 to 60 metres, against 200 to 400 metres in a sawmill. But the density of capture points is much higher. A mid-size kitchen cabinet shop running a CNC router, two panel saws, an edge bander, a wide-belt sander and an assembly area has 14 to 22 dust capture branches converging on a single mid-size dust collector. The branch sizing, the blast-gate scheme, the balancing of the network and the maintenance of conveying velocity across changing operating conditions are where most quotations go wrong.

The regulatory frame is shifting. In 2025 the United States National Fire Protection Association consolidated NFPA 484 (combustible metals), NFPA 654 (combustible particulate solids), NFPA 655 (sulphur) and NFPA 664 (woodworking) into a single combined NFPA 660 standard for combustible dusts. Australian insurers, fire engineers and state regulators reference the consolidated NFPA 660 for joinery and cabinetmaking from 2025 onward. Australia's native AS 3957 (Dust Hazard Assessment) was published in 2024 and is now the local equivalent of the NFPA 660 DHA process. The joint NFPA 660 / AS 3957 framework is the current compliance reference for any joinery, cabinet, furniture or millwork shop SBKJ engineers in 2026.

This guide is the reference our engineers use at our Box Hill North VIC office when we quote an Australian custom joinery, kitchen cabinet, furniture manufacturing or architectural millwork duct package. It covers the design codes that apply, the process zones that drive sizing and material selection, the hazardous area classification that drives the bonding and Ex-rating scheme, the spray finishing duty that drives the stainless and spark-resistant fan specification, and the SBKJ machine configuration we deploy. Read alongside our Sawmill, Timber and Plywood HVAC Duct Engineering Guide for the upstream side of the wood industry, our Automotive Paint Booth HVAC Duct Engineering Guide for the spray finishing parallel, and our Welding Methods HVAC Duct Fabrication Guide for the stainless construction methods that underpin the solvent-exhaust duct.

2. The Australian regulatory framework

Twelve standards govern HVAC ductwork in Australian joinery, cabinetmaking, furniture manufacturing and architectural millwork facilities. Four are mechanical ventilation and ductwork codes, four are combustible dust and fire codes, three are flammable liquids and spray finishing codes, and one is the engineered wood substrate code that drives sheet-good chemistry.

2.1 AS 1668.2 — Mechanical ventilation

AS 1668.2 is the umbrella industrial mechanical ventilation standard for Australia. It sets minimum outside air per occupant for the office, showroom and amenities portions of the facility, capture velocity targets for industrial process exhaust hoods serving the production zones, and references the workplace exposure standards published by Safe Work Australia for chemical contaminants. For joinery and furniture manufacturing, the AS 1668.2 capture velocity targets apply at every dust capture hood face — 1.0 m/s at a planer or moulder enclosure, 1.5 m/s at a partially-open machine table such as a router or a sander, and 0.5 m/s at the face of a downdraft spray booth grating. Dilution ventilation across the general shop floor is typically 6 to 10 air changes per hour, rising to 10 to 15 ACH in the paint mix room and finishing room where solvent vapour control governs.

2.2 AS 4254 — Ductwork for air-handling systems

AS 4254 is the Australian ductwork fabrication standard, parts 1 and 2 covering flexible duct and rigid duct respectively. AS 4254.2 sets the gauge schedule for galvanized steel rectangular and round duct as a function of duct size and operating pressure, the joint and seam standards for low, medium and high-pressure ductwork, and the leakage classification by pressure class. For joinery and cabinetmaking dust extraction, the standard pressure class is Class C (medium-pressure positive 500 to 1000 Pa or negative 250 to 500 Pa at suction side of fan). AS 4254.2 conformity is the SBKJ default for every duct package we quote in Australia.

2.3 AS 1530.4 — Fire-rated duct

AS 1530.4 covers fire-resistance testing of building elements. Where a joinery or furniture factory shares a building envelope with adjoining tenancies — common in tilt-up industrial estates — the duct penetration through a fire-rated wall or floor must be fire-rated to the same FRL as the wall or floor it passes through. Fire-rated duct in a joinery context is typically the spray booth exhaust where it discharges through a building boundary wall, and the office HVAC return where it crosses a tenancy boundary. SBKJ supplies fire-rated dampers and the matching duct collars as part of the duct package.

2.4 AS 3957 — Dust hazard assessment

AS 3957 was published in 2024 as the Australian equivalent of the United States NFPA 660 DHA requirement. Every facility processing combustible dust at a quantity threshold (around 12 kilograms per shift in joinery and cabinetmaking) must complete a documented Dust Hazard Assessment covering ignition sources, dust accumulation locations, engineered controls and a residual risk register. The DHA is refreshed every 5 years and re-issued whenever the process changes. SBKJ engineers work alongside the facility's DHA consultant or fire engineer to ensure the duct design supports the documented controls — the bonding scheme, the spark detection, the explosion vent sizing and the isolation valve all flow from the DHA findings.

2.5 NFPA 660 — Combustible particulate solids (formerly NFPA 484, 654, 655, 664)

In 2025 the United States National Fire Protection Association consolidated four prior standards into the combined NFPA 660 standard for combustible dusts. The pre-2025 NFPA 664 (woodworking facility fire protection) and NFPA 654 (combustible particulate solids) are now both folded into NFPA 660 chapters 30 and 23 respectively. Australian insurers, fire engineers and the larger furniture operator group safety teams reference NFPA 660 as the current global benchmark. The headlines for joinery and cabinetmaking: settled wood dust deeper than 1.6 mm (1/16 inch) anywhere in the facility is a housekeeping failure requiring immediate correction, dust collectors and elevated bin vents must have deflagration vents sized to NFPA 68, isolation valves at the duct between machinery and the dust collector are mandatory, and a continuous dust deposition monitoring programme is required under any insurer's policy. SBKJ duct designs follow NFPA 660 because that is the insurer requirement on every Australian joinery and furniture project in 2026.

2.6 NFPA 68 — Explosion venting

NFPA 68 sets the engineering design rules for deflagration venting — the vent panels and ducting that direct an in-progress dust explosion to a safe area outside the building, limiting peak pressure in the protected vessel. The standard provides Kst-based sizing equations for vent area as a function of vessel volume, deflagration index of the dust, vessel strength and vent burst pressure. Kst for dry pine sawdust is around 150 bar·m/s, hardwood around 200, MDF sander dust 200 to 250. The dust collector vent panels for a typical joinery cyclone-plus-bag-filter combination are 1.0 to 2.5 square metres aggregate vent area, discharging to a safe area outside the building. SBKJ supplies the duct package with the vent panel mounting flanges welded in at the factory.

2.7 NFPA 69 — Explosion prevention

NFPA 69 covers explosion prevention systems where venting is not feasible — for example a dust collector located within a building envelope without external wall access. The prevention options include inertion (continuous nitrogen purge of the collector internal volume), oxidant concentration reduction, deflagration suppression (sodium bicarbonate or monoammonium phosphate discharged within milliseconds of deflagration detection) and pressure containment (the vessel is built to withstand the maximum deflagration pressure). Joinery and furniture applications typically use chemical suppression on the dust collector where external venting is impractical, with the suppression supplier coordinating the duct interface to the SBKJ-supplied isolation valve flange.

2.8 AS/NZS 60079 — Hazardous areas

AS/NZS 60079.10.2 is the Australian and New Zealand adoption of IEC 60079-10-2 covering classification of areas where combustible dust may be present. Zone 20 is where a combustible dust cloud is continuously or frequently present — the interior of dust collectors and the cyclone discharge volume. Zone 21 is where a dust cloud is likely in normal operation — around the dust collector access doors and inspection hatches when opened, and around explosion vent discharges during a deflagration event. Zone 22 is where a dust cloud is unlikely in normal operation but may occur briefly — the interior of every closed dust extraction duct and the volume immediately around access doors, transfer points and bag filter explosion vents. A typical joinery dust extraction system is Zone 22 inside every spiral main, with localised Zone 21 around the cyclone access door and the bag filter explosion vent discharge.

AS/NZS 60079.10.1 covers flammable gas and vapour hazardous areas. In a joinery, furniture or architectural millwork facility the relevant zones are at the paint mix room (Zone 2 around solvent storage cabinets, Zone 1 inside ventilated solvent cabinets), the spray booth interior during operation (Zone 1 when spraying, Zone 2 between cycles), and the curing room or oven if solvent-borne finish is being cured (Zone 2). All electrical equipment in these zones must carry Ex e or Ex d certification as appropriate, and all metal ductwork must be electrically bonded under 10 ohms to plant earth.

2.9 AS 1940 — Flammable and combustible liquids storage and handling

AS 1940 is the Australian standard for storage and handling of flammable and combustible liquids. It sets the quantity thresholds that trigger flammable liquid licensing (typically 25 litres of Class 3 flammable liquid for office occupancy, scaling up with occupancy classification), the bunding and spill containment requirements, the separation distances between storage and other plant, the ventilation rates for solvent storage cabinets, and the integration with the AS/NZS 60079 hazardous area classification. For a joinery or furniture shop, AS 1940 governs the paint mix room layout, the solvent decanting station, the rag bin storage and the empty drum storage area. The exhaust ventilation rate for a paint mix room storing more than 250 litres is typically 10 air changes per hour minimum, with the exhaust point at low level to capture the heavier-than-air solvent vapour.

2.10 AS 4114 — Spray painting booths and rooms

AS 4114 is the Australian standard for spray painting booth and spray-painting room design and construction. Part 1 covers the booth itself, part 2 covers installation and operation. AS 4114 face velocity 0.5 m/s minimum for solvent-borne, 0.4 m/s for waterborne, with the standard recommending higher 0.6 to 0.75 m/s for 2K polyurethane and isocyanate-containing finishes. The booth must have interlocked lights and exhaust fan, fire-rated booth construction (typically 60-minute FRL panel), spark-resistant fan construction per AMCA 99 Type B at minimum, conductive booth floor or grating, and emergency manual override on the exhaust fan. SBKJ supplies the booth supply plenum and the exhaust ductwork to AS 4114 conformity, working alongside the booth OEM who supplies the booth body and the booth-mounted lighting and instrumentation.

2.11 NFPA 33 — Spray application using flammable and combustible materials

NFPA 33 is the United States National Fire Protection Association standard for spray finishing using flammable and combustible materials. It is the de facto international standard for spray booth and spray room safety and is referenced by Australian state regulators and insurers as a complement to AS 4114. Key NFPA 33 requirements that map to the SBKJ duct specification: spray booth exhaust ductwork must be of metal construction (aluminium and plastic are prohibited), exhaust velocity in the booth must be sufficient to prevent solvent vapour concentrations exceeding 25 percent of the lower explosive limit, exhaust ductwork must be electrically continuous and bonded, and the exhaust fan must be of spark-resistant construction. The 25 percent LEL limit is the regulatory cap; SBKJ designs to a 10 percent LEL working margin to allow for transient peaks during topcoat application.

2.12 AS 6122 — Engineered wood products

AS 6122 is the Engineered Wood Products Association of Australasia (EWPAA) product certification standard for plywood, LVL, particleboard, MDF and OSB sold into Australian construction and joinery markets. AS 6122 sets formaldehyde emission classification (E0, E1, super-E0) for MDF and particleboard, structural performance for LVL and plywood, and dimensional and moisture-content tolerances. The HVAC implication for the joinery shop is that the substrate material specification — typically E0 or super-E0 for kitchen cabinets and furniture, E1 acceptable for hidden carcass — determines the formaldehyde load at the cut edge and therefore the capture velocity at the machine head. E0 MDF emits formaldehyde at less than half the rate of E1, allowing tighter occupied-zone concentration with the same extract air volume.

3. Process zones in an Australian joinery and furniture facility

A typical Australian custom joinery, kitchen cabinet, furniture or architectural millwork facility is a sequence of process zones, each with a distinct HVAC duty. We walk through them in production order, calling out the duct duty, the material selection and the SBKJ specification.

3.1 Sheet material storage and incoming inspection

Most Australian joinery and cabinet shops buy MDF, particleboard, melamine-faced chipboard, hardwood plywood and softwood plywood in 2400 by 1200 mm or 3600 by 1800 mm sheet form. Borg Manufacturing at Oberon NSW, Polytec at Penrith NSW and Laminex Australia (Fletcher Building) at multiple sites — Dardanup WA, Ipswich QLD, Gympie QLD — between them supply most of the sheet-good substrate for Australian joinery. Storage is typically flat horizontal stacks on bearer rails, or vertical A-frame racks for limited-floor-area shops. Ventilation here is dilution only — air change rate 4 to 6 per hour driven by formaldehyde off-gassing from E1 board (typically 0.05 to 0.1 ppm at room ambient with no machining) and operator thermal comfort. Galvanized G90 supply and return duct, no special considerations.

3.2 Cutting and machining — CNC router

The CNC router is the dominant single dust source in a modern joinery, cabinetmaking or architectural millwork shop. A 3-axis or 5-axis router with 9 to 15 kW spindle at 18,000 to 24,000 rpm running 12 mm to 32 mm sheet stock generates 8 to 35 kilograms per hour of mixed dust and chip at peak operation, with the fines fraction (under 500 microns) running 30 to 55 percent of total mass depending on tool geometry, feed rate and substrate. Capture is via a brush-skirted dust shoe at the spindle, with a 150 mm to 200 mm dia branch duct connecting to the dust extraction main. Capture velocity at the dust shoe face is 1.5 m/s minimum, branch velocity 22 m/s minimum. The dust shoe is the single most-critical maintenance item in the entire dust extraction network — a worn or stretched brush skirt drops capture efficiency from 95 percent to 60 percent and the lost dust accumulates on the machine bed, the work surface and the floor.

Duct material at the CNC router branch is galvanized G90, 1.2 mm wall thickness minimum, spiral construction per AS 4254. The branch from the dust shoe to the main is fitted with a blast gate at the main tee, allowing the branch to be isolated when the router is not running and balancing flow back to the operating machines. Zone 22 inside the duct continuously, full electrical bonding to under 10 ohms to plant earth. SBKJ supplies the branch in factory-fabricated 3-metre lengths with brass M8 bonding lugs welded to each section, copper strap bridging at every flange joint.

3.3 Cutting and machining — panel saw and beam saw

The panel saw (single-blade with scoring) or beam saw (sliding head with automated infeed) is the second-largest dust source in a kitchen cabinet or architectural millwork shop. A panel saw running 36-tooth carbide blade on a 16 mm melamine-faced MDF sheet generates 4 to 8 kilograms per hour at peak production, with the scoring blade contributing the fines that dominate the combustible fraction. A beam saw running automated cutting cycles can sustain 12 to 25 kilograms per hour. Capture is via two hoods — one at the upper saw blade above the cutting line, one at the lower hood beneath the cut, with a third capture at the scoring blade where fitted. Combined branch flow per panel saw is typically 1800 to 2500 m³/hour at 22 m/s conveying velocity, branch duct 200 mm to 250 mm diameter spiral.

Duct material galvanized G90, 1.2 mm spiral, blast-gate at the main tee. SBKJ specifies abrasion-resistant elbows at every 90-degree change of direction within 5 metres of the panel saw outfeed, because the melamine-faced board chip is harder than ordinary sawdust and abrades elbow throat walls at 0.05 to 0.1 mm per year. Sandwich-construction elbows with replaceable inner wear plate are standard.

3.4 Cutting and machining — edge bander

The edge bander applies PVC, ABS, melamine or solid timber edge tape to the cut edges of a panel using EVA or polyurethane hot-melt adhesive. Capture is at multiple points along the bander — the pre-milling station that flushes the panel edge, the trimming station that cuts the protruding edge tape flush with the panel face top and bottom, the corner-rounding station that profiles the front and back edges, and the buffing station that polishes the trimmed edge. Each station has a hood feeding a branch duct at 22 m/s, with branch diameters 80 mm to 150 mm depending on station and machine size. The combined extract for a single mid-size edge bander is 1200 to 2200 m³/hour, with the highest concentration of trim chip and adhesive fume at the trimming station.

Duct material galvanized G90, 1.2 mm spiral. The hot-melt adhesive fume contains traces of low-volatility hydrocarbons but is below the threshold that would drive stainless construction. Adhesive condensate can accumulate in the branch duct over time — SBKJ supplies the edge bander branches with a low-point drain valve at the elbow nearest the bander, allowing manual drainage every 3 to 6 months.

3.5 Cutting and machining — solid timber planer and moulder

Architectural millwork shops and furniture makers running solid timber (hardwood or softwood mouldings, profiled panels, frame components) operate a planer, moulder, spindle moulder or thicknesser at the cutting and machining stage. Dust generation is heavier than the sheet-good shop because solid timber generates higher chip volume per kilogram of throughput. A 4-head moulder running 90 by 35 mm profiled hardwood at 25 metres per minute generates 80 to 200 kilograms per hour of chip and shavings, with capture at each head requiring a 200 mm to 300 mm diameter branch at 22 m/s. The combined extract for a multi-head moulder is 5,000 to 10,000 m³/hour from a single machine.

The solid-timber moulder dust load shifts the dust collector sizing significantly — a shop with a moulder typically operates a primary cyclone for chip separation, with the cyclone discharging chip to a hog or directly to a chip bin, and the cyclone clean-air outlet ducting to a baghouse for fines filtration. SBKJ specifies the cyclone inlet and outlet duct in 1.6 mm galvanized G90 spiral with abrasion-resistant elbows, the baghouse interconnect in 1.2 mm galvanized G90 spiral, and full electrical bonding throughout. Spark detection at the cyclone inlet is mandatory under NFPA 660 because solid timber chips contain occasional ferrous fragments from worn cutter knives and bandsaw blades.

3.6 Cutting and machining — bandsaw and crosscut saw

The bandsaw and crosscut saw are secondary cutting stations used for solid timber dimensioning, curved cuts and trim-to-length operations. Dust generation is moderate — 1 to 4 kilograms per hour per machine — and capture is via a hood beneath the cutting line feeding a 100 mm to 150 mm diameter branch at 20 m/s. Galvanized G90, 1.2 mm spiral, standard treatment. The fines fraction is lower than the panel saw or CNC router because the kerf is wider and the cut is intermittent.

3.7 Sanding — wide-belt and contact sanders

Sanding is the highest-risk dust source in a joinery, cabinetmaking or furniture shop. The dust is the finest in the entire process, with a wide-belt sander running 120-grit or 180-grit on a melamine-faced MDF panel generating dust with median particle size under 80 microns and a significant fraction under 10 microns. The combustible classification is unambiguous — sanding dust has the lowest minimum ignition energy in the entire joinery process, and the deflagration index Kst can reach 250 bar·m/s on MDF sander dust against typical hardwood sawdust at 150 to 200 bar·m/s.

Capture is via close-coupled enclosures at every contact roll, with branch duct velocity 18 m/s minimum and hood face velocity 0.5 to 1.0 m/s. Branch diameter 150 mm to 250 mm per contact roll, with a 4-head wide-belt sander typically requiring 4 to 6 branches at 4,500 to 7,500 m³/hour combined extract. Duct material galvanized G90, 1.2 mm spiral, with the entire run electrically bonded under 10 ohms to plant earth. The dust collector serving the sander must have deflagration venting per NFPA 68 and chemical suppression where venting to a safe area is not feasible — sanding dust can sustain a primary deflagration even at relatively low loading.

SBKJ specifies spark detection at the sander branch with infrared sensor and water injection or fast-acting damper, set immediately downstream of the sander outfeed. The sander is the highest-probability ignition source in the joinery shop because the high-speed belt running against hardwood or MDF generates frictional heat, and a chipped or torn belt can throw glowing fragments into the duct. Spark detection plus isolation valve plus deflagration vent on the dust collector is the three-layer NFPA 660 protection for the sanding circuit. SBKJ supplies the duct package with all interface flanges for the spark detection and isolation valves welded in at the factory.

3.8 Sanding — random orbital and hand sander stations

Hand sanding for finishing prep — final pass on a furniture piece, between-coat sanding on a cabinet door, profile sanding on a moulding — is performed at dedicated sanding tables or downdraft tables fitted with sub-table extraction. The extract is at the table grating, capture velocity 0.5 m/s at the grating face, branch duct 150 mm to 200 mm diameter at 18 m/s conveying velocity. Galvanized G90, 1.2 mm spiral, bonded.

3.9 Assembly hall

The assembly hall is where the cut and sanded components are joined into the finished cabinet, furniture piece or millwork element. Most assembly is dry — screw, dowel, nail, biscuit — with minor extract requirement for the occasional glue line (PVA water-based or polyurethane hot-melt PUR), the occasional shop-vac for clean-up, and the general dilution ventilation. Air change rate 4 to 6 ACH driven by occupant comfort. Galvanized G90 supply and return duct, no special treatment.

3.10 Paint mix room

The paint mix room is where the spray-finishing materials are decanted from drum or bulk container, tinted to specification, viscosity-checked, and supplied to the spray gun pots. The room typically holds 200 to 1500 litres of Class 3 flammable liquid (acetone, MEK, toluene, xylene, ethyl acetate, isopropyl alcohol) in drum stock plus working-day quantities at the mix bench. AS 1940 governs the storage layout, the bunding, the separation distances and the ventilation rate. AS/NZS 60079.10.1 classifies the room as Zone 2 with localised Zone 1 in solvent storage cabinets and at decanting stations.

Ventilation is dedicated mechanical extract at 10 air changes per hour minimum, with the extract point at low level (within 300 mm of the floor) to capture heavier-than-air solvent vapour. The make-up air is high-level supply to drive vapour movement toward the extract. Duct material on the paint mix room extract is 304L stainless steel because solvent condensate is mildly acidic and would attack zinc within 24 months. The exhaust fan is in AMCA 99 Type B spark-resistant construction at minimum, with Ex e motor enclosure where the fan is located in the Zone 2 envelope.

SBKJ specifies 1.5 mm 304L stainless spiral, TIG-welded longitudinal seam, conductive gaskets at every flange and access door, and full electrical bonding to under 10 ohms to plant earth. The discharge stack is also 304L stainless, terminated at a wind-resistant cap 3 metres above the building roof line per AS 4114 spray finishing exhaust discharge guidance.

3.11 Spray booth — downdraft for high-volume kitchen cabinet door production

The downdraft spray booth is the standard for high-volume flat-panel spray finishing — kitchen cabinet doors, drawer fronts, flat furniture panels, architectural millwork doors. Air enters at the ceiling through a filtered supply plenum, flows vertically through the working volume at 0.5 m/s face velocity, and exits at the floor through a filtered grating into a sub-floor exhaust pit. The exhaust pit connects to the exhaust ductwork, which rises through an exhaust filter bank, the exhaust fan, and the discharge stack.

Duct material on the booth supply plenum and the sub-floor exhaust pit is galvanized G90, 1.2 mm wall, rectangular construction per AS 4254 with Pittsburgh seam and TDF flange. SBKJ fabricates the supply plenum and the exhaust pit on the SBAL-V auto duct production line, with the plenums shipped flat-pack for on-site assembly. The exhaust ductwork from the pit to the discharge stack is 304L stainless for solvent-borne finishes and 316L stainless for 2K polyurethane finishes — the isocyanate hardener condensate is more aggressive than ordinary solvent condensate and 304L can pit at chloride traces in some 2K formulations.

The exhaust fan is AMCA 99 Type B spark-resistant construction at minimum, with the fan motor outside the Zone 1 / Zone 2 envelope wherever possible. The discharge stack is 316L stainless for 2K and 304L stainless for general solvent-borne, terminated at a wind cap 3 metres above the building roof line. SBKJ specifies the stack with insulation external where the stack passes through unconditioned space, preventing solvent vapour from condensing back into the duct interior.

3.12 Spray booth — semi-downdraft for furniture and architectural piece work

The semi-downdraft spray booth is the standard for furniture spraying and architectural millwork piece work — pieces too tall, too irregular or too varied in geometry for full downdraft. Air enters at a partial ceiling plenum at the front of the booth, flows diagonally down and toward the rear wall, exits through a wall-mounted exhaust filter bank, and discharges through the exhaust ductwork to the roof stack. Face velocity 0.5 to 0.75 m/s at the operator working position.

Duct material is the same as full downdraft — galvanized G90 supply plenum and exhaust filter bank casing, 304L or 316L stainless exhaust duct depending on finish chemistry. The geometry is more compact than full downdraft because the exhaust pit is replaced by a wall plenum, so the duct fabrication volume per booth is typically 30 to 50 percent less than the equivalent downdraft installation. SBKJ-supplied semi-downdraft duct packages typically run 80 to 200 metres of equivalent fabricated rectangular and round duct per booth.

3.13 Spray booth — cross-draft for stain and seal application

The cross-draft booth is the simpler and lower-cost spray booth configuration, suitable for stain and seal application on furniture, joinery and architectural elements where overspray is light and the finish is fast-drying. Air enters at the front of the booth through a filtered supply, flows horizontally across the working volume at 0.5 m/s face velocity, and exits at the rear wall through a filtered exhaust into the discharge ductwork. Cross-draft is uncommon in modern Australian furniture and cabinet shops for solvent-borne topcoat application because the operator is unavoidably downstream of the workpiece overspray, but it remains in use for stain and sealant application where finish layer is thin and overspray is minimal.

Duct material is galvanized G90 on the supply and 304L stainless on the exhaust. SBKJ fabricates cross-draft duct packages on the SBAL-V auto duct line for the rectangular supply plenum and the exhaust filter bank, with the discharge stack on the SBFB-1500 spiral former.

3.14 Curing room — UV-cured, IR-cured, oven-dried

After spray application, the finish must cure or dry before the next coat or final packing. The cure mechanism depends on the finish chemistry:

• UV-cured acrylic and UV-cured polyurethane — the workpiece passes through a UV tunnel where high-intensity UV lamps initiate radical polymerisation in seconds to minutes. The tunnel exhausts ozone (UV light dissociates ambient oxygen into ozone) and low-molecular-weight oligomer fume. Capture is at the tunnel exit, with 304L stainless exhaust duct routing to a stack with optional activated carbon scrubber or thermal oxidiser depending on emission limits. Air change rate inside the tunnel envelope is 20 to 40 per hour to maintain ozone at safe operator boundary concentration.
• IR-cured (infrared) acrylic and polyurethane — the workpiece sits under or passes through infrared lamps that elevate the surface temperature to 60 to 90 °C for accelerated solvent flash and cross-link. Solvent evaporation rate is high, requiring 6 to 10 air changes per hour in the IR cure room and 304L stainless exhaust ductwork from the room to the discharge stack.
• Oven-dried solvent-borne and water-borne finishes — the workpiece passes through a hot-air oven at 40 to 70 °C for accelerated solvent flash. The oven exhaust is solvent-rich at solvent flash temperature, requiring 304L stainless exhaust duct and a thermal oxidiser or scrubber on discharge where local emission limits apply.

SBKJ supplies the cure room and oven exhaust ductwork in 304L or 316L stainless depending on chemistry, with insulation external where the duct passes through unconditioned space to prevent solvent condensation back into the duct interior.

3.15 Veneer and lamination press

Architectural millwork and high-end furniture manufacturing often involves veneer-faced or laminated panel components where a decorative veneer or melamine paper is bonded to a substrate using heated press cycles. Adhesive chemistry varies — urea-formaldehyde, melamine-urea-formaldehyde, polyurethane, polyvinyl acetate, contact cement. Capture is at the press infeed and outfeed, with the press platen heat driving solvent or water vapour out of the adhesive layer and into the working envelope. Capture velocity 1.5 m/s at hood face, branch duct 200 mm to 300 mm diameter at 20 m/s.

Duct material depends on adhesive chemistry. Urea-formaldehyde and melamine-urea-formaldehyde release formaldehyde, but at the press infeed and outfeed the concentration is low and galvanized G90 is acceptable. Polyurethane releases trace isocyanate vapour during press cure, requiring 304L stainless capture duct because zinc reacts with isocyanate over time and creates a residue that interferes with finish adhesion on the next panel. Contact cement (solvent-based polychloroprene) requires 304L stainless because the solvent is aggressive to galvanized. SBKJ specifies by adhesive chemistry on a per-project basis.

3.16 Glue line — PVA water-based and PUR hot-melt

The general glue line in a joinery, cabinetmaking or furniture shop applies polyvinyl acetate water-based adhesive (PVA) or polyurethane hot-melt (PUR) for case construction, dowel jointing, edge gluing or laminated component bonding. PVA is the dominant chemistry for Australian joinery and cabinetmaking — water-based, low odour, no VOC concern, minor extract requirement. PUR is used for moisture-resistant assembly (kitchen carcass bottom rails, bathroom vanity construction, marine joinery). PUR cures with moisture and releases isocyanate fume during application, requiring local exhaust at the glue applicator.

Capture at the PVA glue applicator is minimal — typically a 100 mm to 150 mm flexible hose connected to the main shop dust extraction at the operator station, drawing 200 to 400 m³/hour at the applicator. Capture at the PUR glue applicator is more substantial — 600 to 1200 m³/hour at the applicator, drawing through a 150 mm to 200 mm diameter branch in 304L stainless because the isocyanate fume would attack galvanized over time. The PUR branch routes to the spray booth exhaust or to a dedicated stack rather than the dust extraction system because the chemistry and the flow regime are incompatible with the combustible-dust circuit.

3.17 Finishing room — stain, sealer, topcoat application stations

Outside of the spray booth, many joinery and furniture shops have additional finishing stations for hand-applied stain, wipe-on sealer, brush-applied topcoat, and touch-up. These stations are typically alcoves off the main finishing room with overhead spot exhaust at 1.0 m/s capture velocity and branch duct 150 mm to 200 mm at 20 m/s conveying velocity. Duct material 304L stainless because the solvent vapour load is significant and continuous, even though peak concentrations are lower than the spray booth.

3.18 Drying tunnel and flash-off conveyor

Between spray application and curing, sprayed components pass through a drying tunnel or flash-off conveyor where solvent evaporates from the wet film. The tunnel exhaust is solvent-rich at solvent flash temperature, requiring 304L stainless exhaust duct routing to the stack via a thermal oxidiser or scrubber depending on local emission limits. SBKJ specifies the drying tunnel exhaust in 1.5 mm 304L stainless, insulated external, with low-point drains to manage condensate.

3.19 Polishing and buffing station

After cure, some furniture and architectural pieces are polished or buffed for a high-gloss finish. The polishing or buffing operation generates fine dust — polish compound residue, lacquer film dust, occasional metal trace from the buffing wheel mandrel. Capture is at a downdraft polishing booth or a polishing extraction hood at 1.0 m/s capture velocity, branch duct 150 mm to 200 mm at 18 m/s. Galvanized G90, 1.2 mm spiral, bonded for combustible dust precaution (polish compound and lacquer film dust can be combustible at high loading).

3.20 Steam bending shop (specialty antique-style joinery)

A small number of Australian specialty joinery and antique-restoration shops operate a steam-bending station for forming curved timber components — chair backs, balustrade rails, decorative arches. The steam-bending box is a sealed timber or steel chamber holding the workpiece in saturated steam at 100 °C for 30 to 120 minutes, then transferred to a forming jig for cooling under tension. The exhaust at the steam-bending box is wet hot air, requiring 304L stainless exhaust duct because galvanized would corrode from continuous saturated steam exposure. The duct routes to a roof discharge or a heat-recovery unit, with insulation external to maintain wall temperature above the dew point.

3.21 Foam carving and pattern shop (millwork prop fabrication)

Some architectural millwork shops, particularly those serving the film and TV production sector, operate a foam carving station for prop fabrication and decorative element prototyping. EPS, XPS and PU foam carving generates fine fibrous dust and trace solvent fume (PU foam off-gas during machining). Duct material galvanized G90 on the dust extract, 304L stainless on the PU foam exhaust if a dedicated branch is provided. The foam carving cross-references our Film, TV Production Studio and Soundstage HVAC Duct Engineering Guide for the prop fabrication zone treatment.

3.22 Timber kiln chamber (integrated facilities)

Some integrated Australian joinery and furniture facilities operate an on-site timber kiln chamber for in-house drying of solid timber to working moisture content (typically 10 to 14 percent for indoor furniture, 12 to 16 percent for joinery). The kiln chamber and its vent duct mirror the larger sawmill kiln duty discussed in our sawmill guide, but at smaller scale — 304L or 316L stainless kiln vent duct, condensate management at low points, insulation external to maintain wall temperature above the dew point. Cross-reference our Sawmill, Timber and Plywood HVAC Duct Engineering Guide for the full kiln vent specification.

3.23 Finished goods storage warehouse

Finished cabinetry, furniture and millwork must be stored at controlled humidity to prevent warping, joint movement and finish craze. Australian joinery and furniture industry consensus is 40 to 60 percent relative humidity year-round at 18 to 24 °C. The warehouse HVAC is supply and return ductwork with a dedicated dehumidification or humidification unit, sized to the warehouse volume and the local ambient envelope. Duct material galvanized G90 throughout, conventional rectangular construction. SBKJ fabricates the warehouse HVAC on the SBAL-V auto duct line.

3.24 Office, showroom and display room

The office and customer-facing showroom are conditioned space with conventional commercial HVAC — galvanized G90 supply and return ductwork, AS 1668.2 minimum outside air at 10 L/s per person, AS 2107 acoustic target NC-35 to NC-40 depending on use. The display room where finished products are presented to customers requires additional fine-dust filtration on the supply air to keep the displayed product clean — typical filter spec MERV 13 supply filtration with HEPA option for premium showrooms. SBKJ supplies the office and showroom duct package on the SBAL-V auto duct line, conventional commercial HVAC fabrication.

4. Material selection summary

The SBKJ material specification framework for an Australian joinery, cabinetmaking, furniture or architectural millwork facility reduces to a decision tree by duct duty.

4.1 Galvanized G90 — the workshop dust extraction baseline

• Branches and mains for sheet-good dust extraction — CNC router, panel saw, edge bander, wide-belt sander, downdraft sanding table.
• Branches and mains for solid-timber dust extraction — planer, moulder, spindle moulder, thicknesser, bandsaw, crosscut saw.
• Cyclone interconnect — between primary cyclone and secondary bag filter on heavy-load extraction circuits.
• Spray booth supply plenum — both downdraft and semi-downdraft ceiling supply.
• Spray booth exhaust pit — sub-floor exhaust collection chamber on downdraft booth construction (the wet condensate is on the booth interior side of the filter bank, not the duct side).
• Office, showroom and amenities — supply and return HVAC, standard commercial fabrication.
• Finished goods storage warehouse — humidity-controlled storage HVAC.
• Veneer press capture for water-based and formaldehyde adhesive — formaldehyde concentration is low in conveying duct at typical capture air volumes.

Wall thickness 1.0 mm minimum for branches up to 250 mm diameter, 1.2 mm minimum for branches and mains 250 to 500 mm, 1.6 mm minimum for mains above 500 mm. Coating G90 zinc minimum (275 g/m² total both faces) per AS 1397.

4.2 304L stainless steel — the solvent and isocyanate duty

• Spray booth exhaust duct — from the booth exhaust filter bank to the discharge stack on solvent-borne lacquer, stain, sealer and 2K polyurethane finishing booths.
• Spray booth discharge stack — typically 304L for solvent-borne, 316L for 2K polyurethane with chloride traces.
• Paint mix room exhaust — solvent storage room extract.
• Curing room exhaust — IR cure, UV cure tunnel exhaust, oven dry exhaust.
• Finishing room hand-application station exhaust — stain, sealer, brush topcoat alcoves.
• Drying tunnel and flash-off conveyor exhaust — solvent flash duty.
• PUR hot-melt glue applicator local exhaust — isocyanate vapour capture.
• Steam-bending chamber exhaust — saturated steam duty.

Wall thickness 1.2 mm minimum for branches up to 250 mm, 1.5 mm minimum for branches and mains above 250 mm. Spiral construction per AS 4254, TIG-welded longitudinal seams where rectangular construction is required.

4.3 316L stainless steel — the chloride and acid duty

• 2K polyurethane spray booth exhaust where chloride-containing formulations are in use (HCl trace from acid-catalysed cure).
• Integrated timber kiln vent — acetic acid condensate from hardwood drying.
• Marine-grade joinery and antique restoration shop solvent exhaust where saltwater-adjacent ambient corrosion risk is elevated (Sydney harbour-side, Brisbane river-front, Perth coastal joinery).

Wall thickness 1.5 mm minimum throughout. Spiral construction per AS 4254, TIG-welded longitudinal seams where required.

4.4 Aluminium — prohibited in dust and finishing duty

Aluminium duct is prohibited in any duct conveying combustible wood dust under NFPA 660, and prohibited in solvent-rich spray booth exhaust under NFPA 33. The justification is spark generation under impact — a tool dropped on aluminium duct, a fragment thrown by the source equipment, or duct support hardware striking the duct can produce a spark above the minimum ignition energy of fine wood dust or solvent vapour. SBKJ does not supply aluminium duct in joinery and furniture applications.

5. Conveying velocity targets by source

Conveying velocity in joinery and furniture dust extraction ductwork is set by the heaviest particle that must remain entrained at the lowest design flow rate. Sub-velocity operation causes settlement, settled dust ignites under spark, and the system propagates to deflagration. The SBKJ targets:

• Wide-belt sander fine dust — 18 m/s minimum at the worst-case branch flow.
• Panel saw and CNC router mixed dust and chip — 20 to 22 m/s.
• Edge bander trim with adhesive fragments — 22 m/s.
• Planer and moulder shavings — 22 m/s.
• Bandsaw and crosscut saw mixed sawdust — 20 m/s.
• Hand sanding station downdraft table — 18 m/s minimum.
• Polishing and buffing fine dust — 18 m/s.
• Cyclone-to-bag-filter interconnect — 22 m/s.
• Spark detection branch downstream of sander — 22 m/s (slight margin over baseline to ensure detection reliability).

These are minimum velocities at the worst-case operating condition. SBKJ engineering specs spiral mains at peak operating flow including the load case where 70 to 80 percent of branches are open with the rest blanked off — the load case where main flow drops without changing main diameter. Designing for design-average flow guarantees settlement and combustible deposit accumulation within 12 months.

6. Hazardous area classification

Every Australian joinery, kitchen cabinet, furniture and architectural millwork facility we have surveyed has the same hazardous area profile.

• Zone 22 inside every dust extraction duct. Combustible wood dust cloud unlikely in normal operation but may occur briefly. Applies to every CNC router, panel saw, edge bander, sander, planer, moulder and polishing extraction branch and main.
• Zone 22 around every duct flange, branch tee and access door. The volume immediately adjacent the dust-carrying duct.
• Zone 21 around the cyclone access door, the bag filter access door, the dust collector explosion vent discharge area. Dust cloud likely in normal operation when access door is opened or during a deflagration event.
• Zone 20 inside the dust collector, the cyclone discharge volume and any silo or surge bin internal volume. Combustible dust cloud continuously or frequently present.
• Zone 2 around the paint mix room solvent storage cabinets. Flammable vapour unlikely in normal operation but may occur briefly. Applies to the volume within 3 metres of cabinet doors.
• Zone 1 inside the paint mix room ventilated solvent cabinets and at decanting stations during decanting. Flammable vapour likely in normal operation.
• Zone 1 inside the spray booth during spraying. Solvent vapour at typically 8 to 15 percent LEL during topcoat application.
• Zone 2 inside the curing room when solvent-borne finish is curing. Solvent vapour above 0 but below 25 percent LEL.

The implications for duct fabrication and installation:

• Electrical bonding. Every flange joint bridged with a 6 mm² copper bonding strap, terminated to a brass M8 bonding lug welded to each spiral section at SBKJ. Resistance across every joint under 1 ohm, resistance from the most distant point on the duct system to plant earth under 10 ohms. Measured at commissioning and re-tested every two years and after any modification.
• Conductive gaskets. All access doors, hatches, inspection ports and cleanout ports fitted with conductive EPDM or conductive silicone gaskets. Non-conductive gaskets are prohibited in dust-conveying duct and solvent-conveying exhaust duct.
• Flexible connectors. Where vibration isolation is required at fan inlets and outlets, flexible connectors must be of conductive construction with internal bonding strap continuity. Non-metallic flexible connectors are prohibited.
• Ex-rated equipment. Damper actuators, instrumentation, isolation valve actuators, spark detection sensors and any electrical fitting installed in Zone 22 must carry Ex tD or Ex tc certification. Equipment in Zone 1 (spray booth interior, paint mix room solvent cabinets) requires Ex e or Ex d certification. SBKJ-supplied duct accessories include certified actuators and instruments as standard on all hazardous-area projects.
• Spark-resistant fans. Every fan handling combustible wood dust or solvent vapour exhaust must be in AMCA 99 Type B spark-resistant construction at minimum, with Type A required where the dust load includes embedded ferrous fragments (planer, moulder, bandsaw downstream). Fan motors outside the Zone 1 / Zone 2 envelope wherever practical, with Ex-rated motor enclosure where the motor must be inside the envelope.

7. Spark detection and deflagration protection

The three-layer NFPA 660 protection scheme for combustible wood dust in joinery and furniture extraction is:

• Spark detection at the source-side duct. Infrared sensor mounted on the duct wall, viewing the duct interior at 90 degrees to the airflow direction, detecting glowing fragments at temperatures above 300 °C. Detection triggers a fast-acting response — water injection through a quick-opening valve mounted upstream of the sensor (suppression by saturation), or a fast-acting damper that closes the duct within 200 milliseconds (isolation by mechanical block), or both. Spark detection is mandatory under NFPA 660 at every duct downstream of a sander, a planer, a moulder, a bandsaw and any other ignition-source machinery.
• NFPA 68 deflagration venting at the dust collector. Vent panels sized per Kst-based equations to the protected volume and the dust deflagration index, vented to a safe area outside the building free of personnel and assets. Vent panel burst pressure 0.1 to 0.2 bar gauge typical, with the panel opening within 10 milliseconds of overpressure.
• Isolation valves between the source machinery and the dust collector. Fast-acting mechanical or chemical isolation that prevents flame propagation back into the workshop through the duct in the event of a deflagration at the collector. SBKJ supplies the duct package with isolation valve mounting flanges welded in at the factory, allowing the suppression supplier to fit their hardware on site.

Where deflagration venting to a safe area is not feasible — typically because the dust collector is located inside a building envelope without external wall access — the protection scheme substitutes chemical suppression under NFPA 69. The chemical suppression system detects a developing deflagration within milliseconds and discharges sodium bicarbonate or monoammonium phosphate suppressant into the protected volume before the deflagration can fully propagate. SBKJ supplies the duct interface flanges for the suppression supplier's hardware.

8. Spray booth exhaust — the AS 4114 / NFPA 33 specification

The spray booth exhaust duct is the most heavily-specified single duct run in a joinery, furniture or architectural millwork facility. AS 4114 and NFPA 33 together set the following requirements that flow to the SBKJ duct package.

• Material. Metal construction required. Aluminium and plastic prohibited. SBKJ default 304L stainless for solvent-borne finishing, 316L stainless for 2K polyurethane with chloride traces.
• Wall thickness. 1.2 mm minimum for branches and mains, 1.5 mm minimum where the duct routes through a fire-rated wall or floor.
• Construction. Spiral construction per AS 4254 for round duct 200 mm to 1600 mm diameter, TIG-welded longitudinal seam rectangular construction where rectangular geometry is required at the booth exhaust filter bank.
• Joints. Welded or flanged with conductive gaskets. Slip-and-drive joints prohibited in solvent-conveying duct — solvent condensate would weep at slip joints, drip on building structure, and accumulate combustible residue on adjacent surfaces.
• Bonding. Full electrical continuity, copper strap at every joint, brass M8 lug to plant earth.
• Cleanouts. Removable access ports at every 6-metre run length and at every change of direction, sized to allow physical access for cleaning. Solvent residue accumulation in the duct interior is the primary spray booth fire ignition source, and routine cleaning at 6-month to 12-month intervals is required by AS 4114 and most insurer policies.
• Slope. Continuous slope toward a low-point drain on horizontal runs, allowing condensate to drain. Drain valve to a sealed condensate container.
• Insulation. External rockwool 50 mm minimum where the duct passes through unconditioned space, preventing solvent condensation back into the duct interior.
• Discharge. Discharge stack terminated at a wind-resistant cap 3 metres above the building roof line, away from any building outside air intake by at least 7.5 metres horizontal distance.
• Fan. AMCA 99 Type B spark-resistant construction at minimum, with the fan motor outside the Zone 1 / Zone 2 envelope where practical.

SBKJ fabricates the spray booth exhaust duct package on the SBAL-V auto duct line for the rectangular plenum work at the booth filter bank, and on the SBFB-1500 spiral former for the round exhaust mains and the discharge stack. The TIG seam welder delivers the leak-tight longitudinal welds required for AS 4114 conformity on rectangular sections, with the SBSF-1525 round tube flanging machine producing the flanged ends for the round-to-rectangular transitions and the stack terminations.

9. Acoustic targets

Australian joinery and furniture industry HVAC noise targets follow AS 1668.2 and AS 2107 guidance:

• Industrial production area (CNC router, panel saw, sander, finishing) — NC-50 to NC-55 acceptable. Process noise from the machinery dominates and HVAC duct noise is a secondary contribution.
• Assembly hall — NC-45. Lower process noise allows tighter HVAC target.
• Paint mix room — NC-40. Operator spends shifts in the room, intercom communication required, HVAC noise must not fatigue.
• Office and design studio — NC-35 to NC-40. Standard commercial.
• Customer showroom and display room — NC-30 to NC-35. Quiet environment for customer consultation and product display.
• Finished goods warehouse — NC-50. No tight acoustic requirement.
• Boundary noise to neighbours. State EPA guideline applies — Victorian EPA Publication 1826 sets 50 dB(A) at sensitive receptors at night for industrial premises, dropping to 35 dB(A) in residential-adjacent zones. NSW EPA Industrial Noise Policy and similar state instruments set comparable limits elsewhere. Acoustic louvres and silencers at intake and discharge stacks typically required to meet boundary limits in suburban industrial estates.

AS 3580 covers boundary air quality at the building envelope perimeter, complementing the acoustic boundary limits. Spray booth exhaust discharge must meet the AS 3580 boundary limits for VOC, total particulate and any specific listed contaminant — typically formaldehyde, toluene, xylene and total VOC for joinery and furniture finishing.

10. Australian operators and the joinery and furniture sector landscape

The Australian joinery, kitchen cabinet, furniture and architectural millwork sector consolidated significantly over the past decade. The current operator landscape we engage with at SBKJ:

10.1 Kitchen cabinet and joinery — manufacturer-distributor channel

Polytec (Penrith NSW) is the country's largest decorative laminate and door manufacturer, supplying the cabinetmaker channel nationally. Polytec operates from a flagship Penrith site producing thermolaminated and high-pressure laminate doors, drawer fronts and panel components for kitchen, bathroom and commercial joinery. The HVAC profile is the integrated kitchen cabinet plant — panel cutting, edge banding, sanding, finishing and packing. SBKJ specification for a Polytec-style facility is the full joinery duct package with galvanized G90 at dust extraction and 304L stainless at the press exhaust and finishing duct.

Laminex Australia (Fletcher Building) operates from Dardanup WA, Ipswich QLD and Gympie QLD producing particleboard, MDF and decorative panel sheet products. Laminex is upstream of the cabinetmaker but operates an integrated plant where the cabinetmaker-relevant duties — panel manufacturing, edge work, finishing — share the broader sheet-good plant. Cross-reference our Sawmill, Timber and Plywood HVAC Duct Engineering Guide for the upstream MDF and particleboard plant duty.

Borg Manufacturing (Oberon NSW + Mt Druitt NSW) is the other major Australian particleboard and MDF producer, with an integrated furniture component and kitchen cabinet door operation downstream of the panel mill. SBKJ duct specification at Borg-style integrated operations covers both the upstream sheet-good plant and the downstream component manufacturing.

10.2 Kitchen cabinet — bespoke and franchised retail

Kinsman Kitchens (Fyshwick ACT) is a bespoke kitchen cabinet manufacturer with a national franchise retail network and centralised production. The Fyshwick facility runs a typical mid-size cabinet shop layout — CNC router, beam saw, edge bander, wide-belt sander, spray booth, assembly and finishing. SBKJ specification for a Kinsman-style facility is the joinery duct package at moderate scale — 14 to 22 dust capture branches, single mid-size cyclone-plus-bag-filter dust collector with NFPA 68 deflagration venting, single semi-downdraft spray booth or downdraft spray booth, 304L stainless on finishing exhaust.

Designer Kitchens for Living, Freedom Kitchens (Steel Building Products), Wallspan, IKEA Australia and the Bunnings Group (Wesfarmers ASX:WES) source kitchen cabinet components from a mix of in-house and contracted manufacturing across the country. The Bunnings retail channel sources from local cabinetmakers regionally and from IKEA Australia for the IKEA brand. IKEA Australia maintains warehousing and assembly capability but production is largely overseas.

10.3 Custom and commercial joinery

Jandakot Joinery (Perth WA) is a major Western Australian custom joinery operator serving residential and commercial markets, with a particular concentration in luxury residential and high-end commercial fit-out. The HVAC profile is the custom joinery shop — variable batch sizes, high mix of solid timber and sheet-good, downdraft or semi-downdraft spray booth with full 2K polyurethane capability, finishing room with 304L stainless exhaust throughout.

Bayset (Sydney) is a major commercial joinery operator focused on fit-out for corporate, hospitality and retail clients. Modular Joinery, the Cabinet Maker Awards network operators, and the Australian Joinery Industry Association (AJIA) member shops nationally cover the broader custom joinery landscape. SBKJ specification across the custom joinery sector is consistent — joinery duct package scaled to shop size, with the spray booth and finishing exhaust always in 304L or 316L stainless.

10.4 Furniture manufacturing — luxury and design-led

King Living (Sydney) is one of Australia's leading luxury furniture manufacturers, with a flagship Sydney facility manufacturing custom and made-to-order furniture for the domestic and export markets. The HVAC profile spans the furniture range — solid timber and sheet-good machining, upholstery (separate duct duty), spray finishing with full 2K polyurethane capability, and finishing room. SBKJ specification for a King Living-style facility is the full joinery duct package plus the upholstery extraction (a minor extract duty handled in galvanized G90 conventional construction).

Coco Republic (Sydney), Cosh Living (Melbourne), Boyse Furniture (Sydney), Mim Design + Joinery (Melbourne), Dare Gallery (Melbourne), Tait (Melbourne, outdoor furniture), Made Local Marketplace (Sydney bespoke) and Carrocel Restoration (Sydney antique) cover the broader Australian luxury and design-led furniture landscape. SBKJ engagement with the design-led furniture sector emphasises the spray booth, finishing room and curing room duct package — the difference between an acceptable furniture finishing operation and a class-leading one is heavily on the finishing side.

10.5 Furniture retail — Harvey Norman, Freedom, Snooze

Harvey Norman (ASX:HVN), Freedom Furniture, Snooze (bedding), Plush, Domayne and the broader furniture retail channel source from a mix of domestic and overseas manufacturing. The domestic-sourced product flows from contract manufacturers operating the joinery and furniture duct profile discussed throughout this guide. SBKJ engagement with the retail channel is typically through the contract manufacturer rather than the retailer directly.

10.6 Engineered wood and timber processing

Boral Timber (now Allwood Timbers following Boral's divestment), ASH ARDEX (engineered wood), Hyne Timber (Maryborough QLD), Carter Holt Harvey (CHH, Fletcher Building NZ + AU sites), AKD Softwoods (Colac VIC), OneFortyOne (SA + NZ), Hancock Victorian Plantations (Heyfield VIC), Drouin West Timber & Truss (VIC), Tilling Timber (NSW), Schaeffer Timber (Heyfield VIC), McKay Timber (TAS) and Britton Brothers (TAS) operate upstream of the joinery and furniture sector but supply much of the substrate. The detailed sawmill, MDF and engineered timber duct profile is covered in our Sawmill, Timber and Plywood HVAC Duct Engineering Guide.

Wesbeam (Neerabup WA) is the Australian LVL benchmark and Tasmanian Special Species Timber (TASST) and the Australian Hardwood Network (AHN) supply specialty timber to the high-end furniture and architectural millwork segment.

10.7 Industry associations

The Cabinet Makers and Designers Association (CMDA) and the Australian Joinery Industry Association (AJIA) — now merged — are the primary industry body for the joinery and cabinet sector. The Furniture and Bedding Industries Association (FBIA) covers the furniture and mattress sector. Master Builders Australia covers the broader construction and building-products sector including joinery and millwork. Forest and Wood Products Australia (FWPA), the Engineered Wood Products Association of Australasia (EWPAA), the Timber Development Association (TDA) and the Australian Sustainable Hardwoods (ASH) network cover the upstream timber and wood-products supply chain.

11. Common quotation errors in joinery and furniture duct packages

Reviewing competitor quotations for Australian joinery, cabinet, furniture and architectural millwork duct packages, the recurring patterns:

• Galvanized at the spray booth exhaust. The quotation will read 1.2 mm galvanized spiral throughout the spray booth exhaust to the stack. The duct will corrode at slip joints and flange faces within 18 months from solvent condensate, the corrosion will release combustible residue back into the booth on the next cycle, and the insurer will reject the system at first compliance inspection. SBKJ default is 304L stainless or 316L stainless on every spray booth exhaust from the booth filter bank to the discharge stack.
• No spark detection downstream of the sander. The quotation supplies the sander branch and the dust collector connection but no spark detection at the sander outfeed. NFPA 660 mandates spark detection at every duct downstream of an ignition source — the sander is the highest-probability ignition source in the joinery shop. Insurers require spark detection, and an SBKJ quote that does not include it is incomplete.
• No isolation valve between source and dust collector. The quotation supplies the duct package and the dust collector interface flange but no provision for an isolation valve. NFPA 660 requires an isolation valve to limit flame propagation back into the shop in the event of a collector deflagration. SBKJ supplies the duct with isolation valve mounting flanges welded in at fabrication for the suppression supplier to fit their hardware.
• Conveying velocity at design-average not peak operating. The quotation sizes the spiral main at the average flow assumption — 16 m/s at the sander main against the 18 m/s minimum. The actual peak operating condition with 30 percent of branches blanked off drops main flow to 12 m/s. Settlement begins immediately, deposition exceeds NFPA 660 thresholds within 4 to 6 months, and the next spark from the sander ignites the deposit.
• Aluminium duct in the spray booth exhaust. The quotation specifies aluminium duct because it is lighter to install and lower-cost than stainless. NFPA 33 and AS 4114 prohibit aluminium in solvent-rich exhaust. SBKJ does not supply aluminium in spray booth duty.
• No paint mix room exhaust ductwork. The quotation supplies the spray booth duct package but treats the paint mix room as ambient ventilation with passive louvres. AS 1940 requires dedicated mechanical extract from the paint mix room at minimum 10 ACH where solvent quantity exceeds 250 litres — most joinery and furniture shops hold this quantity easily. SBKJ includes the paint mix room exhaust in every spray-finishing duct package.
• Slip-and-drive joints in the solvent exhaust. The quotation specifies conventional slip-and-drive on the spray booth exhaust rectangular sections. Solvent condensate weeps at slip joints over time, drips on building structure and creates a combustible residue accumulation. SBKJ specifies welded or fully-flanged joints with conductive gaskets on all solvent-exhaust ductwork.
• No insulation on the curing room exhaust. The quotation supplies the curing room duct from the room to the stack but no external insulation. The duct cools below the solvent dew point overnight, solvent condenses back into the duct interior, and the next operating shift carries the condensate back to the booth or the cure room. SBKJ insulates curing room exhaust externally with 50 mm rockwool and aluminium cladding.
• Standard commercial fan on the dust collection circuit. The quotation specifies a generic centrifugal fan on the dust collector outlet. NFPA 660 requires AMCA 99 Type B spark-resistant construction at minimum, with Type A where embedded ferrous fragments are likely (any duct downstream of a planer, moulder or bandsaw). SBKJ supplies the fan to AMCA 99 conformity and the certificate of conformity is included in the FAT package.
• No condensate drain on the spray booth exhaust. The quotation supplies the spray booth exhaust duct but no low-point drain. Solvent condensate accumulates in the duct interior, drips at joints, and forms a flammable residue inside the duct that becomes the next ignition source. SBKJ includes a low-point drain valve to a sealed condensate container at every spray booth exhaust low point.

12. The SBKJ machine configuration for Australian joinery and furniture

The duct package for a typical Australian custom joinery, kitchen cabinet, furniture or architectural millwork facility combines galvanized spiral mains for dust extraction, galvanized rectangular for the spray booth supply plenum and the office HVAC, 304L stainless spiral and rectangular for the finishing exhaust, and 316L stainless where 2K polyurethane and chloride exposure governs. The SBKJ machine configuration we deploy at our Box Hill North VIC office to fabricate this package:

12.1 SBAL-V — Auto duct production line for rectangular work

The SBAL-V Auto Duct Line is the SBKJ U-shape automatic duct production line for rectangular galvanized duct, supporting TDF flange, angle flange and drive cleat joint profiles in coils up to 1500 mm wide (SBAL-V-1500J) and 1250 mm wide (SBAL-V-1250J). Models are SBAL-V-1250J and SBAL-V-1500J. For the joinery and furniture package, the SBAL-V fabricates the spray booth supply plenum and exhaust filter bank casing in galvanized G90, the office and showroom HVAC supply and return ductwork, the finished goods storage warehouse HVAC, and the rectangular sections of the finishing room exhaust where 304L stainless coil is run through the line with the cutting and folding stations switched to stainless mode. Output capacity at a typical Australian joinery duct project is 50 to 200 metres of equivalent rectangular duct, completed on the SBAL-V in 4 to 6 working shifts. The SBAL-V is certified to ISO 9001:2015 and CE marking.

12.2 SBFB-1500 — Spiral former for high-volume dust extraction mains

The SBFB-1500 is SBKJ's high-volume spiral former configured for joinery dust extraction main fabrication, capable of forming spiral from 100 mm to 1500 mm diameter in galvanized G90 or 304L stainless coil. The continuous lockformed spiral seam eliminates the longitudinal weld of rolled construction and the smooth internal surface eliminates dust accumulation points where settled material could ignite. For the joinery and furniture package, the SBFB-1500 produces the CNC router and panel saw branches (typically 150 mm to 300 mm diameter), the sander branches (150 mm to 250 mm), the dust extraction main (typically 400 mm to 700 mm diameter), the cyclone-to-bag-filter interconnect (300 mm to 500 mm), and the spray booth exhaust round sections (300 mm to 600 mm).

12.3 SBSF-1525 — Round tube flanging machine

The SBSF-1525 Round Tube Flanging Machine produces the flanged ends for round duct connections — branch tees to mains, transitions from round to rectangular at the spray booth filter bank, stack base connections, and cyclone interconnect flanges. The SBSF-1525 handles galvanized, stainless and aluminium coils. For the joinery and furniture package, the SBSF-1525 produces flanged ends on every round spiral duct section, allowing on-site assembly with conductive gaskets and full electrical bonding continuity. The flange profile is selected to match the project specification — TDF, angle flange or proprietary fast-connect depending on site preference. ISO 9001:2015 and CE certified.

12.4 TIG seam welder — Stainless leak-tight construction

The SBKJ TIG seam welder produces leak-tight longitudinal welds in 304L and 316L stainless plate up to 3 mm thickness, used at the spray booth exhaust rectangular sections, the curing room exhaust, the paint mix room exhaust, and the cyclone hopper stainless fabrication where required for solvent-finishing-adjacent installations. TIG welds are pickle-passivated to restore corrosion resistance at the heat-affected zone, then leak-tested with a soap solution at low pressure before despatch from Box Hill North VIC. The TIG seam welder is the third pillar of the SBKJ stainless duct package after the SBAL-V auto duct line and the SBFB-1500 spiral former. Reference our Welding Methods HVAC Duct Fabrication Guide for detailed coverage of the stainless welding methods that underpin the leak-tight construction.

12.5 Spark-resistant fan supply

SBKJ supplies the dust extraction fan and the spray booth exhaust fan to AMCA 99 Type B spark-resistant construction at minimum, with Type A available where embedded ferrous fragments are likely in the dust load. The fan supply is part of the integrated duct package on every Australian joinery and furniture project — single point of accountability for the duct, the fan, the spark detection interface and the isolation valve interface. The AMCA 99 conformity certificate is included in the FAT documentation.

12.6 SBSF-1525 stitchwelder for cyclone hopper stainless fabrication

Where the dust collection cyclone hopper requires stainless construction — typically for finishing-adjacent installations where solvent residue could contact the cyclone interior or where corrosion management drives stainless throughout — SBKJ uses the SBSF-1525 stitchwelder configuration for the cyclone hopper plate joining. The stitchwelder produces the leak-tight intermittent welds required for the hopper construction, with full pickle-passivation post-fabrication.

13. Specification checklist for an Australian joinery and furniture project

A buyer evaluating duct quotations for an Australian custom joinery, kitchen cabinet, furniture or architectural millwork project should ask each supplier to confirm the following items in writing:

• Process zone schedule. Has the supplier walked the proposed shop layout and documented each ventilation zone with its temperature, humidity, dust load and chemical exposure? Boilerplate specification applied across all zones is a red flag.
• Dust Hazard Analysis interface. Has the supplier coordinated with the facility's AS 3957 DHA consultant, and does the duct design reflect the DHA findings on bonding, spark detection, vent sizing and isolation valves?
• Hazardous area drawing. Does the supplier provide a plan and elevation hazardous area drawing showing Zone 20, 21 and 22 boundaries per AS/NZS 60079.10.2, plus Zone 1 and 2 boundaries per AS/NZS 60079.10.1 for the paint mix room and spray booth? Without this drawing, the bonding scheme and Ex-rated equipment selection cannot be verified.
• Material specification by duct duty. Has the supplier specified galvanized G90, 304L stainless or 316L stainless at each duct run, and justified the selection against the chemical exposure? Specifying galvanized at the spray booth exhaust is a quotation that should be rejected immediately.
• Conveying velocity by source. Has the supplier confirmed conveying velocity at each branch and main, at peak operating condition not design average? Velocity below SBKJ targets is a deflagration risk and a settlement risk.
• Bonding and earthing schedule. Does the supplier provide a bonding and earthing schedule showing every flange, every joint, every access door and every flexible connector, with copper bonding strap size and earth resistance target?
• Spark detection scheme. Does the supplier provide the spark detection location, the sensor type, the response action (water injection or fast-acting damper) and the interface to the dust collector control system?
• NFPA 68 vent sizing. Does the supplier or the dust collector supplier provide an NFPA 68 deflagration vent sizing drawing showing vent area, vent ducting (if any) and vent discharge area location per NFPA 660 chapter 30?
• AS 4114 spray booth specification. Does the supplier confirm booth face velocity, exhaust filter specification, fan AMCA 99 conformity, stack discharge location and the interlock scheme between booth lights and exhaust fan?
• Paint mix room ventilation. Does the supplier provide a dedicated paint mix room exhaust at 10 ACH minimum, with low-level extract point and high-level supply, and 304L stainless duct throughout?
• Cleanout access on solvent exhaust. Does the supplier provide removable access ports at every 6-metre run length on the spray booth exhaust ductwork, allowing physical access for the 6-month to 12-month cleaning cycle?
• Condensate management. Does the supplier provide low-point drains with sealed condensate containers on the spray booth exhaust, the curing room exhaust and the steam-bending exhaust where applicable?
• Commissioning report. Does the supplier commit to a complete commissioning report covering branch flow measurement, main velocity verification, dust deposition audit at 24 hours and 7 days, earth continuity certification, spark detection functional test, NFPA 68 vent sign-off, spray booth face velocity at four positions, and leak test on the spray booth exhaust?
• Spare-parts and maintenance package. Does the supplier commit to spare-parts continuity for at least 10 years, with documented lead time and pricing basis?

14. Cost ranges for Australian joinery and furniture duct packages

Indicative installed cost ranges for HVAC duct packages on Australian joinery, kitchen cabinet, furniture and architectural millwork projects, current to early 2026, in Australian dollars excluding GST:

• Small bespoke joinery shop — 400 to 800 square metres, 8 to 14 dust capture branches, single small downdraft or cross-draft spray booth — AUD 180k to 380k installed duct package.
• Mid-size kitchen cabinet shop — 800 to 1500 square metres, 14 to 22 dust capture branches, single semi-downdraft or downdraft spray booth with 2K PU capability, paint mix room with AS 1940 compliance — AUD 380k to 750k installed.
• Large integrated cabinet and joinery plant — 1500 to 3000 square metres, 22 to 40 capture branches, multiple spray booths, finishing room with multiple stations, UV or IR curing — AUD 750k to 1.5M installed.
• Custom furniture manufacturing facility — solid timber plus sheet-good, full 2K PU finishing, finishing room with multiple stations — AUD 600k to 1.2M installed.
• Architectural millwork facility with veneer and lamination — premium for the veneer press capture and the larger spray booth — AUD 700k to 1.4M installed.
• Luxury furniture manufacturer with multiple spray booths — typically 2 or 3 booths spanning waterborne, solvent-borne and 2K capability — AUD 1.0M to 2.2M installed.
• Integrated kitchen cabinet manufacturer (Polytec or Kinsman scale) — full sheet-good plant downstream of board manufacturing — AUD 1.8M to 3.5M installed for the duct package.

Cost ranges exclude the dust collector, the spray booth body, the curing tunnel, the spray booth fan and the paint mix room solvent storage cabinets — those are separate equipment lines that interface with the SBKJ-supplied duct package at the flange. SBKJ provides the engineering interface drawings to align all sub-suppliers and acts as the single point of accountability for the duct package and the fan supply where the fan is purchased through SBKJ.

15. Project delivery timeline

A typical Australian joinery, kitchen cabinet, furniture or architectural millwork duct package from quotation to commissioning runs 14 to 24 weeks. The phases:

• Quotation and engineering (3 to 5 weeks) — site walk, process zone schedule, DHA coordination, hazardous area drawing, material specification by duty, velocity sizing, spark detection scheme, NFPA 68 vent sizing coordination, equipment interface drawings, fixed-price quotation.
• Order to fabrication start (2 to 3 weeks) — order confirmation, coil and plate procurement (galvanized G90 and 304L or 316L stainless), shop drawing release for client and fire engineer approval.
• Fabrication (5 to 10 weeks) — spiral mains and branches on the SBFB-1500, rectangular plenum and offices on the SBAL-V, stainless TIG-welded sections on the TIG seam welder, accessories including blast gates, bonding lugs, conductive gaskets, isolation valve mounting flanges, low-point drains. Larger integrated cabinet plant projects can extend to 12 to 14 weeks fabrication.
• Factory acceptance test (1 to 2 weeks) — dimensional verification, weld inspection on stainless sections, leak test on spray booth exhaust runs, bonding lug verification, packing and crating.
• Shipping and installation (3 to 5 weeks) — road transport from Box Hill North VIC to site, mechanical installation by site contractor, bonding strap and earth installation, flexible connector installation, fan installation, spark detection sensor mounting.
• Commissioning (1 to 2 weeks) — branch flow measurement, main velocity verification, earth continuity test, spark detection functional test, NFPA 68 vent sign-off (coordinated with dust collector supplier), spray booth face velocity verification, operations and maintenance manual handover.

16. Maintenance schedule for joinery and furniture duct systems

The Australian joinery and furniture duct system requires a documented maintenance schedule under NFPA 660, AS 4114 and most insurer policies. The SBKJ-recommended schedule:

• Daily. Visual inspection of dust deposition at floor level in production zones, blast gate operation check on dust extraction branches, fan running indicator confirmation, spray booth filter saturation indicator check.
• Weekly. Spray booth pre-filter exchange or cleaning (paint stop filters, manometer-based replacement trigger), paint mix room solvent cabinet visual inspection, fire damper visual check on fire-rated penetrations.
• Monthly. Spray booth main filter inspection and replacement as needed, dust collector pre-filter inspection, spark detection sensor functional test, bag filter shake-down cycle verification, low-point condensate drain emptying on spray booth and curing room exhaust.
• Quarterly. Dust collector main filter inspection (some bag filter designs run quarterly cleaning cycles), AS 1851 fire damper test, conductive gasket inspection at access doors, flexible connector inspection.
• Annually. Spray booth exhaust duct interior cleaning (residue removal at all accessible points), dust extraction duct interior cleaning including hidden runs, AS 4114 booth recommissioning (face velocity at four positions, fan AMCA conformity verification, interlock test), AS 1668.2 capture velocity verification at every hood face, NFPA 68 vent panel inspection.
• Biennial. Earth continuity test on every Zone 22 duct section, isolation valve functional test under simulated deflagration trigger, fan bearing replacement on high-duty installations.
• Five-year. AS 3957 DHA refresh — full re-issue of the Dust Hazard Analysis with updated ignition source register and engineered control verification. NFPA 660 housekeeping audit. Insurer recommissioning.

Reference our HVAC Duct Machinery Maintenance Schedule guide for the broader maintenance framework and our HVAC Duct Sealants and Gaskets Guide for the conductive gasket selection that supports the bonding scheme.

17. Why galvanized fails in joinery finishing duty — the three case patterns

We have replaced too many failed galvanized duct runs in Australian joinery and furniture shops to recommend galvanized anywhere on the finishing side. The three case patterns:

17.1 Spray booth exhaust corrosion

Galvanized duct on the spray booth exhaust typically fails in 12 to 24 months. The mechanism: solvent condensate (ketone, ester, aromatic hydrocarbon) accumulates on the duct wall during operation and at shift-end. Solvent residue plus airborne moisture forms a mildly acidic mixed condensate that attacks the zinc coating, creating a soft white deposit (zinc compound from solvent reaction) that flakes off and accumulates inside the duct. The bare steel beneath then corrodes by mixed atmospheric and solvent attack. Failure mode is wall thinning at the slip joints, weeping condensate, drips on building structure beneath the duct, and ultimately structural collapse. 304L stainless eliminates this failure mode.

17.2 Paint mix room exhaust corrosion

Galvanized duct on the paint mix room exhaust typically fails in 18 to 30 months. The mechanism: continuous low-level solvent vapour exposure forms a thin condensate film on the duct interior that attacks zinc slowly over time. Unlike the spray booth exhaust the load is more dilute and chronic rather than acute, so the failure mode is more uniform — gradual zinc loss across the entire interior surface, eventually reaching the steel and beginning general atmospheric corrosion. Wall thinning is slower than the spray booth case but the duct fails by gradual leakage at flanges before structural failure. 304L stainless eliminates this failure mode.

17.3 Curing room exhaust corrosion

Galvanized duct on the curing room or oven exhaust typically fails in 18 to 36 months. The mechanism: elevated temperature (40 to 90 °C) accelerates the solvent attack on zinc relative to ambient operation, and the duct cycles through dew point each shift as the cure oven heats up and cools down. Condensate forms at the duct interior during cool-down, evaporates at warm-up, leaving the dissolved zinc compounds and solvent residue accumulated on the duct wall. The cycle compounds the attack. Failure mode is similar to the spray booth — wall thinning, joint weeping, eventual collapse. 304L stainless eliminates this failure mode.

18. The 2K polyurethane finish — why it drives 316L stainless on some installations

Two-part polyurethane is the highest-performance furniture and architectural millwork topcoat in widespread Australian use. The chemistry: a polyol base and an isocyanate hardener combine on application, cross-link as the solvent flashes off, and form a tough, chemically-resistant, UV-stable film. The isocyanate is typically HDI (1,6-hexamethylene diisocyanate) or MDI (4,4-methylene diphenyl diisocyanate) or an oligomer derivative. The solvent is typically MEK, xylene, toluene or n-butyl acetate.

The exhaust duct duty on 2K polyurethane finishing is more demanding than ordinary solvent-borne. The reasons:

• Isocyanate vapour reactivity. Free isocyanate in the exhaust air condenses on the duct wall and reacts with any moisture present, forming oligomers that adhere to the duct interior. The deposit is harder than solvent residue and is harder to clean.
• Chloride traces. Some 2K PU formulations include chloride-containing co-solvents or acid catalysts that drive 304L stainless to pit at the chloride concentration thresholds. 316L stainless is more resistant to chloride pitting at the levels typical in 2K PU exhaust.
• Operator safety. The Safe Work Australia STEL for isocyanate is 0.005 ppm — there is no known safe respiratory exposure level. Capture must be complete, leakage must be zero, and any duct degradation that allows leakage back into the operator zone is unacceptable.

SBKJ specifies 316L stainless on the 2K PU spray booth exhaust from the booth filter bank to the discharge stack, with TIG-welded seams on rectangular sections and conductive gaskets at all flange joints. The fan is AMCA 99 Type B spark-resistant at minimum, with Type A where embedded ferrous fragments are present from upstream sanding.

19. The kitchen cabinet door manufacturing case — high-volume melamine-faced production

The kitchen cabinet door manufacturer is a specialised cabinet shop running high-volume production of melamine-faced MDF and particleboard doors with thermolaminated or PVC-edge profiles. Polytec at Penrith NSW is the country's largest such operator, supplying the cabinetmaker channel nationally. The HVAC profile differs from the bespoke joinery shop on three dimensions:

• Volume. A kitchen cabinet door plant runs continuous production, often 24/7 across two or three shifts. The dust load is sustained rather than batch, and the dust collector is sized for continuous operation rather than peak with quiescent recovery. Dust collector cleaning cycle frequency is higher, baghouse pulse-jet cleaning is essentially continuous, and the spark detection circuit is monitored 24/7.
• Material. Melamine-faced MDF and particleboard are the dominant substrate. The face material is melamine-impregnated paper laminated to MDF or particleboard at the panel manufacturer. When the cabinet door manufacturer cuts the panel, the cut edge releases formaldehyde plus mineral fragments from the melamine impregnation, and the dust load is higher in fines and harder to capture than ordinary MDF dust. Capture velocity at the panel saw and CNC router is at the top of the SBKJ specification range — 22 m/s rather than 20 m/s.
• Finishing. The finishing duty is typically thermolamination of additional decorative paper to the cut panel face, or thermal edge banding with PVC or ABS tape, or in some cases solvent-borne edge sealing. Spray finishing is uncommon at the kitchen cabinet door manufacturer because the consumer product is already finish-faced from the panel manufacturer. SBKJ duct specification at a kitchen cabinet door plant is therefore dominated by dust extraction with limited spray finishing duct.

20. The architectural millwork case — bespoke joinery for commercial fit-out

The architectural millwork facility serves the commercial fit-out market — corporate office reception desks, hotel furniture, retail shop fitouts, restaurant joinery, hospitality bar construction. Bayset at Sydney, Mim Design + Joinery at Melbourne and the broader commercial millwork channel cover this segment. The HVAC profile differs from the volume kitchen cabinet plant on three dimensions:

• Mix. Architectural millwork runs a high mix of solid timber, sheet-good, veneered substrate, and occasional solid surface and stone-look products. The substrate mix changes by project and the dust extraction circuit must handle the worst-case material in any given shift. SBKJ designs the dust extraction main for the heaviest expected load case, not the average.
• Finishing complexity. Architectural millwork finishes range from clear acrylic lacquer on natural hardwood, through 2K polyurethane on premium piece work, to specialty finishes (gold leaf, decorative paint effects, distressed finishes). The finishing duct package therefore needs multi-booth capability — typically one small water-based or acrylic booth, one main 2K PU booth, and a hand-application alcove for specialty work. SBKJ specifies 304L stainless on the acrylic and waterborne booth exhaust, 316L stainless on the 2K PU booth exhaust.
• Veneer and lamination. Architectural millwork frequently involves wood veneer or decorative laminate over an MDF or particleboard substrate, requiring a veneer press and a lamination capture duty. The press capture duct is 304L stainless because the adhesive chemistry (typically urea-formaldehyde, polyurethane or contact cement) drives stainless specification.

21. The luxury furniture case — King Living and the design-led segment

King Living at Sydney, Boyse Furniture, Coco Republic, Tait and the broader design-led furniture manufacturing segment differ from the volume kitchen cabinet and architectural millwork manufacturers on the finishing side. The HVAC profile emphasises:

• Multiple spray booth capability. A typical luxury furniture facility runs 2 to 4 spray booths covering acrylic lacquer, 2K polyurethane, oil-based finish (some product lines), and occasional specialty finish. Each booth has its own supply and exhaust duct, its own fan, and its own discharge stack. The total spray finishing duct package per booth is 80 to 200 metres of equivalent fabricated duct.
• Hand-finishing capability. Beyond the spray booths, the luxury furniture manufacturer typically runs a hand-finishing room with multiple stations for stain application, French polish, oil rub finish, distressing and patination. Each station has overhead spot exhaust at 1.0 m/s capture velocity, branch duct 304L stainless to the main exhaust.
• Curing variety. The luxury furniture finishing schedule may include UV cure (for some panel components), IR cure (for accelerated lacquer flash), oven dry (for slower acrylic and 2K cure), and air dry (for traditional oil and wax finishes). The duct package therefore covers the full range of curing exhaust duties.
• Upholstery extraction. Luxury furniture frequently combines hard joinery with upholstery, requiring a separate extract duty at the upholstery cutting and assembly area. Foam dust, fabric lint and minor adhesive vapour — galvanized G90 standard construction, conventional commercial HVAC fabrication.

22. Antique restoration and specialty timber — Carrocel and the heritage segment

Carrocel Restoration at Sydney and the broader antique restoration sector, plus specialty timber operators like Tasmanian Special Species Timber (TASST), serve the heritage furniture and bespoke timber market. The HVAC profile is bespoke joinery scaled small, but with additional considerations:

• Historic timber exposure. Antique restoration handles timber that may contain lead-based finishes, arsenic-based preservation (older eucalyptus species treated under early AS 1604 standards) and historic insect-treatment residues. The extract duct must handle the mixed chemistry without degradation, and the operator exposure must be managed under AS 1668.2 and Safe Work Australia general workplace exposure limits. 304L stainless on extraction duct where historic finish removal is performed.
• Solvent variety. Restoration uses a wider solvent range than modern furniture — methylene chloride paint stripper (NMP 0.4 ppm STEL is now the more common active under modern formulations), denatured alcohol, mineral spirit, citrus-based strippers, and traditional varnish solvents. The paint mix room and finishing room duct must handle the wider chemistry.
• Steam-bending. Some antique restoration involves steam-bending of replacement components — chair backs, balustrade rails — using a steam-bending box at saturated 100 °C. Cross-reference the steam-bending section above (3.20).

23. The native forestry transition — what it means for joinery and furniture HVAC investment

Australian native forestry is in transition. Victoria announced the phase-out of native forest logging by the early 2030s, Western Australia ended native forest logging at the end of 2023, and several other states have committed to similar transitions. The implication for joinery and furniture HVAC investment is two-fold.

First, the solid timber input mix is shifting from native hardwood to plantation hardwood, plantation softwood and engineered timber substrates. Plantation softwood and engineered timber generate different dust profiles than native hardwood — softwood dust is generally lower-density and conveys at slightly lower velocity than hardwood dust at the same particle size distribution. Engineered timber (LVL, plywood, CLT) generates resin-bound dust that conveys similarly to MDF and particleboard dust. The HVAC duct sizing and material specification holds across the transition — galvanized at extraction, stainless at finishing — but the conveying velocity targets shift down marginally at the heaviest planer and moulder duties.

Second, the architectural millwork and luxury furniture segments increase emphasis on certified plantation hardwood and managed-forest specialty timber, with traceability and chain-of-custody documentation required by the end-customer in commercial fit-out and premium residential projects. The HVAC investment per dollar of revenue trends upward marginally because the higher-value finished product justifies the higher-performance finishing capability — multi-booth spray rooms, 2K PU capability, controlled-humidity finished goods storage — that drives the duct package complexity.

24. How SBKJ scores against the Australian joinery and furniture brief

We use this guide as the engineering reference when our customers ask us to quote a custom joinery, kitchen cabinet, furniture or architectural millwork duct package at our Box Hill North VIC office. The short version of where SBKJ stands:

• Process zone engineering. Full site walk and zone schedule on every quotation, not boilerplate spec. DHA coordination with the facility's AS 3957 consultant.
• Hazardous area drawing. Plan and elevation drawing per AS/NZS 60079.10.1 and AS/NZS 60079.10.2 supplied with every quotation, Zone 1, 2, 20, 21 and 22 boundaries marked.
• Material specification. Galvanized G90, 304L stainless, 316L stainless each justified per duty. Stainless at every spray booth, paint mix room, curing room and finishing room exhaust as standard.
• Conveying velocity. Sized at peak operating condition, not design average. 18 m/s sander, 20 m/s panel saw, 22 m/s CNC router and moulder.
• Bonding and earthing. Copper bonding strap and brass M8 lug welded to every spiral section at SBKJ. Resistance under 1 ohm per joint, under 10 ohms system to plant earth.
• Spark detection. Sensor location, water injection or fast-acting damper response, interface to dust collector control — all specified at quotation.
• NFPA 660 / NFPA 68 / NFPA 33 interface. Vent flanges welded into the SBKJ duct package at the factory, isolation valve mounting flanges installed for the suppression supplier, AMCA 99 conformity on every fan supplied through SBKJ.
• Machine configuration. SBAL-V auto duct line for the rectangular work, SBFB-1500 spiral former for the dust extraction mains, SBSF-1525 round tube flanging for connections, TIG seam welder for leak-tight stainless construction. Full SBKJ machine catalogue.
• Australian footprint. Box Hill North VIC engineering and fabrication, Australian site walks, Australian commissioning support, Australian after-sales. About SBKJ Group.

Get an itemised SBKJ duct package quotation for your joinery, cabinet or furniture project →

FAQ

Why is wood dust treated as combustible in a joinery or cabinet shop?

Wood dust under 500 microns has minimum ignition energy below 100 mJ and Kst between 100 and 250 bar·m/s depending on species and substrate. Under AS 3957 and NFPA 660 every facility above the threshold quantity needs a DHA, spark detection at ignition-source machinery, NFPA 68 explosion venting at the dust collector, and full bonding to under 10 ohms to earth.

What duct material does a 2K polyurethane spray booth exhaust need?

316L stainless on the exhaust from the booth filter bank to the discharge stack. 2K PU isocyanate condensate is mildly acidic, some formulations carry chloride traces, and the Safe Work STEL for isocyanate is 0.005 ppm so leakage tolerance is zero. SBKJ default is 316L with TIG-welded seams and conductive gaskets at every joint.

How fast does galvanized duct fail in a spray booth exhaust?

12 to 24 months on a solvent-borne booth, 18 to 30 months on a paint mix room exhaust, 18 to 36 months on a curing oven exhaust. The mechanism is solvent condensate attacking the zinc coating, with the rate accelerated by temperature cycling. 304L stainless eliminates the failure mode.

What is NFPA 660 and when did it apply?

NFPA 660 is the consolidated United States NFPA combustible particulate solids standard published in 2025, replacing NFPA 484 (combustible metals), NFPA 654 (combustible particulate solids), NFPA 655 (sulphur) and NFPA 664 (woodworking). For Australian joinery and furniture, NFPA 660 chapter 30 carries the prior NFPA 664 content. Insurers reference NFPA 660 from 2025 onward.

What is the conveying velocity for a CNC router and panel saw?

CNC router 22 m/s, panel saw 20 m/s, edge bander 22 m/s, wide-belt sander 18 m/s, planer and moulder 22 m/s. Sized at peak operating condition, not design average. Below SBKJ targets the system settles, the deposit ignites, and the next spark propagates.

What is the AS 4114 face velocity for a furniture spray booth?

0.5 m/s minimum for solvent-borne, 0.4 m/s for waterborne, 0.6 to 0.75 m/s recommended for 2K polyurethane. Downdraft booths for high-volume flat panel, semi-downdraft for furniture, cross-draft for stain only. AMCA 99 Type B spark-resistant fan minimum.