organic / Timber / Millwork
Acetylated Wood (Accoya), various profiles (19mm, 25mm, 32mm, 38mm, 50mm)
Chemically modified Radiata Pine achieving Class 1 durability through acetylation. 80% reduction in moisture uptake, exceptional dimensional stability (0.4-0.8% shrinkage), 50-year warranty. Non-toxic, FSC-certified, suitable for cladding, decking, windows, and marine applications.
Atlas code
ORG-TBR-MW-003
At-a-glance signals
Chemically modified Radiata Pine achieving Class 1 durability through acetylation. 80% reduction in moisture uptake, exceptional dimensional stability (0.4-0.8% shrinkage), 50-year warranty. Non-toxic, FSC-certified, suitable for cladding, decking, windows, and marine applications.
Overview
Executive summary
Accoya acetylated wood transforms fast-growing FSC-certified Radiata Pine (Pinus radiata) into a Class 1 durable timber through molecular-level chemical modification. The acetylation process replaces hydroxyl groups in wood cell walls with acetyl groups using acetic anhydride, reducing moisture absorption by approximately 80% and delivering exceptional dimensional stability (radial shrinkage 0.4%, tangential 0.8% wet to 65% RH — compared to 4.8%/7.6% for Douglas Fir). The result is a non-toxic, biocide-free material with tropical hardwood performance from sustainably sourced softwood, backed by an industry-leading 50-year above-ground and 25-year in-ground warranty. Available in multiple profiles from 19mm to 50mm for cladding, decking, windows, doors, and structural joinery.
Best when…
- 50-year above-ground and 25-year in-ground warranty
- Class 1 durability (EN 350) — surpasses Teak and Ironbark for rot resistance
- Exceptional dimensional stability — 80% reduction in moisture uptake
- 100% non-toxic — no biocides, no harmful chemicals, no toxic leaching
- FSC-certified sustainably sourced Radiata Pine
- Excellent machinability — works like natural timber
- Termite resistant (AWPA E1 rating >=9)
- Suitable for marine/coastal applications including salt water splash zones
- Through-core modification — cut ends perform identically to faces
- Available in natural and Color Grey (through-core stain) finishes
Top advantages
- 01 50-year above-ground and 25-year in-ground warranty
- 02 Class 1 durability (EN 350) — surpasses Teak and Ironbark for rot resistance
- 03 Exceptional dimensional stability — 80% reduction in moisture uptake
- 04 100% non-toxic — no biocides, no harmful chemicals, no toxic leaching
- 05 FSC-certified sustainably sourced Radiata Pine
Top limitations
- 01 Premium pricing — significantly more expensive than untreated timber (quote-based in Australia)
- 02 Imported product — manufactured in Netherlands, longer lead times
- 03 Softwood base — Janka 4.1 kN, softer than Australian hardwoods
- 04 Acetic acid (vinegar) odour during initial weathering period
- 05 Higher embodied energy than untreated timber due to acetylation process
Technical
Physical ·8
- Density
- 512 (432-592 range) kg/m3 Average 512-515 kg/m3 at 65% RH, 20 degC. Range 432-592 kg/m3. Thermal conductivity testing measured 514.4 kg/m3 average (495-541 range). Source: Accoya Wood Information Guide V3.9.1, ift thermal test report.
- Specific gravity
- 0.51 (0.43-0.59 range) Average 0.51-0.52 at 65% RH. Range 0.43-0.59. Source: Accoya datasheet, calculated from density.
- Porosity
- 3-5 (EMC at 65% RH) % Reduced porosity due to acetyl groups blocking hydroxyl sites in cell walls. Equilibrium moisture content reduced to 3-5% at 65% RH vs ~12% for untreated Radiata Pine. Source: Accoya Wood Information Guide.
- Water absorption
- 3-5 (EMC) % Acetylation reduces water absorption by approximately 80%. EMC at 65% RH is 3-5% vs ~12% untreated. This is the fundamental mechanism providing durability and stability. Source: Accoya Wood Information Guide.
- Hardness
- 4.1 (side) / 6.6 (end) kN Janka hardness: Side 4,100 N (4.1 kN), End grain 6,600 N (6.6 kN). ASTM D143 test method. Softer than Australian hardwoods but adequate for cladding and joinery. Source: Accoya Performance Testing Summary.
- UV resistance
- Good (with coatings lasting 2-3x longer than on untreated wood) Acetylation does not inherently improve UV resistance. Accoya will grey/silver naturally when uncoated like any timber. Coatings last significantly longer on Accoya due to dimensional stability (reduced cracking/peeling). Source: Accoya specification guide.
- Chemical resistance
- Excellent Excellent chemical resistance. Acetyl group modification provides comprehensive protection against chemical degradation. Suitable for industrial and marine environments. Source: Accoya specification guide.
- pH tolerance
- 3-9 pH Excellent pH tolerance. Acetylated wood shows improved resistance to acidic and alkaline conditions. By-product is acetic acid (vinegar) — the modification itself is pH-neutral when cured.
Mechanical ·5
- Tensile strength
- 40-60 MPa Tensile strength parallel to grain maintained at Radiata Pine levels. Acetylation does not significantly reduce tensile strength. Source: Accoya Performance Testing Summary.
- Compressive strength
- 35-45 MPa Compressive strength parallel to grain. Maintained at or slightly improved over untreated Radiata Pine levels. Source: Accoya datasheet.
- Flexural strength
- 39-40 MPa MOR (Modulus of Rupture) = 39-40 MPa per EN 408. Note: after 10 years ground contact, MOR reduced by 29.6% despite no visible fungal attack. Source: Accoya Wood Information Guide, PMC durability study.
- Impact resistance
- 25-40 J/m Impact resistance comparable to untreated Radiata Pine. Softwood base means lower impact resistance than Australian hardwoods. Source: Accoya datasheet.
- Creep resistance
- Excellent Excellent creep resistance due to improved dimensional stability and reduced moisture cycling. Acetylation reduces internal stress from moisture movement. Source: Accoya Wood Information Guide.
Sustainability & Health
Embodied carbon & energy ·7
- Embodied carbon
- 200-500 (process dependent, before biogenic offset) kg CO2-eq/m3 Higher embodied energy than untreated timber due to acetylation process and intercontinental transport. However, biogenic carbon storage in wood (~250 kg CO2/m3 for Radiata Pine) may offset processing emissions. Accoya EPD available for detailed LCA data. Source: Accoya EPD, timber LCA literature.
- Carbon footprint
- -50 to 300 (accounting dependent) kg CO2-eq/m3 When biogenic carbon (~250 kg CO2/m3) is included, Accoya may be carbon-neutral or carbon-negative. 60+ year service life amortises processing emissions. Extended coating life reduces maintenance-related emissions. Source: Accoya EPD.
- Embodied energy
- 1200-2000 MJ/m3 Includes forestry, sawmilling, acetylation process (acetic anhydride production + treatment), and transport. Higher than untreated timber but offset by 60+ year service life eliminating multiple replacement cycles. Source: Accoya EPD.
- Water footprint
- 60-150 L/kg Forest growth water (Radiata Pine plantation) plus processing water. Acetylation process uses acetic anhydride, not water-intensive. Source: timber lifecycle estimates.
- Recycled content
- 0 % 0% — virgin FSC-certified Radiata Pine required for consistent quality. Source: Accoya.
- Renewable content
- 100 % FSC-certified Radiata Pine from sustainably managed plantation forests (primarily New Zealand). Fast-growing species — harvest cycle 25-30 years. Source: Accoya FSC certification.
- Circular score
- 7.5 /10 Good circular potential. 100% renewable source, 60+ year service life, non-toxic composition enables composting or biomass recovery at end-of-life. Acetyl modification does slow biodegradation (by design). Fully recyclable. Source: Accoya sustainability data.
Health & emissions ·1
- VOC emissions
- <20 (cured) ug/m3 100% non-toxic. No biocides or harmful chemicals. Initial acetic acid odour is food-grade (vinegar) and dissipates. No toxic leaching. Source: Accoya safety data.
Compliance & Fire
Fire performance ·6
- Combustibility class
- Class D (EN) / Class C (ASTM) Combustible material. EN 14915: Class D. ASTM E84: Class C. Can be fire-retardant treated for improved ratings. Important: Radiata Pine base may NOT meet AS 3959 BAL-29 requirements — verify with certifier. Source: Accoya datasheet, AS 3959.
- Fire resistance level
- 30-45 (thickness dependent) minutes Fire resistance depends on section thickness. Can be improved with fire-retardant treatment. Radiata Pine is NOT listed in AS 3959 Appendix F for BAL-29 compliance — Accoya likely requires alternative compliance pathway for bushfire areas. Source: Accoya, AS 3959.
- Ignition temp
- 280-350 degC Softwood ignition temperature range. Similar to untreated Radiata Pine.
- Flame spread index
- Class C (ASTM E84) FSI ASTM E84: Class C. Accoya can be fire-treated to meet higher requirements (Class A/B). Source: Accoya Performance Testing Summary.
- Smoke dev. index
- 200-350 SDI Softwood range smoke development. Similar to untreated Radiata Pine.
- Heat release rate
- 180-300 kW/m2 Softwood-range heat release. Acetylation does not significantly change fire properties. Source: Accoya testing data.
Cost & Lifecycle
Capex & lead time ·6
- Material cost (range)
- 150-300 (estimated, quote-based) AUD/m2 Quote-based pricing in Australia. Accoya is a premium product — pricing not publicly listed. Contact Britton Timbers (1300 BRITTON) for project quotes. Indicative range based on UK/EU pricing adjusted for Australian market. Canterbury Timbers stocks Accoya Natural 185x21mm and Accoya Slate Grey 145x20mm. Source: Australian supplier enquiries.
- Material cost (per unit)
- 6000-15000 (estimated) AUD/m3 Premium volume pricing. Estimated $6,000-15,000/m3 depending on profile and finish. Quote-based — contact Britton Timbers. Source: industry estimates.
- Lead time
- 14-56 days Imported from Netherlands. Britton Timbers maintains Australian stock of standard profiles but specialty orders may require 28-56 days. Accoya Color Grey may have longer lead times. Source: Britton Timbers.
- Lifecycle cost
- 150-350 AUD/m2 Excellent lifecycle value despite premium upfront cost. 50-year warranty with coatings lasting 2-3x longer reduces total maintenance spend. Cost is comparable to alternatives when amortised over service life. Source: Accoya lifecycle analysis.
- Annual maintenance
- 1-3 AUD/m2/year Minimal maintenance. Coatings last 2-3x longer than on untreated timber. Recoat every 8-12 years for cladding. Accoya Color Grey requires even less maintenance. Annualised ~$1-3/m2/year. Source: Accoya lifecycle data.
- Market availability
- Good — national distribution through Britton Timbers + regional stockists Britton Timbers is Australian authorised national distributor. Additional stockists: Canterbury Timbers (Sydney), Austim (Perth), Mathews Timber (Melbourne/Sydney/Brisbane), Gowan Lea Timbers (Sunshine Coast), Franz Building Supplies, Narangba Timbers (QLD). Growing availability but still specialist product. Source: Accoya AU supplier directory.
Service life & durability ·3
- Expected lifespan
- 60+ years 60+ year service life based on accelerated durability testing. 10-year in-ground Greek exposure testing showed no fungal attack despite MOE/MOR reduction. Source: Accoya, PMC durability study (Forests journal).
- Maintenance interval
- 8-12 years Coatings last 2-3x longer on Accoya than untreated timber due to dimensional stability preventing coating failure. Typical recoat interval for cladding: 8-12 years. Accoya Color Grey requires minimal maintenance due to through-core stain. Source: Accoya specification guide.
- Warranty period
- 50 (above ground) / 25 (in-ground) years 50-year above-ground warranty. 25-year in-ground warranty. Salt water splash zone warranty included. Full salt water immersion suitable but warranty does not cover marine organism attack. Source: Accoya warranty documentation.
Layer D
Where it's used
External window and door frames
High-performance cladding systems
Marine and coastal construction
Premium decking and outdoor furniture
Structural millwork and joinery
Commercial and residential exteriors
Heritage restoration projects
Extreme climate applications