organic / Timber / Millwork

Pre-Aged/Greyed Timber Cladding (19mm, 21mm, 25mm)

Factory pre-weathered or naturally-greying timber cladding achieving immediate silver-grey patina. Treatment options include SiOO:X (silicon mineral network), CUTEK oils, or Accoya Color Grey (dyed through core). Silvertop Ash and Spotted Gum substrates achieve BAL-29 for bushfire areas.

Atlas code

ORG-TBR-MW-002

organictimbermillworkpre-agedgreyed-timbersilver-greyweathered-finish

Pre-Aged/Greyed Timber Cladding (19mm, 21mm, 25mm)

At-a-glance signals

Overview

Executive summary

Pre-aged/greyed timber cladding achieves the sought-after silver-grey weathered patina from day one through factory-applied treatments or naturally-greying timber species. Multiple approaches are available: silicon-based systems like SiOO:X that form a mineral silica network within the timber surface producing uniform grey tones after 10-16 weeks; penetrating oil treatments like CUTEK that protect while allowing natural silvering; or acetylated products like Accoya Color Grey that are dyed grey through to the core. Australian hardwoods including Silvertop Ash (Durability Class 2, BAL-29), Spotted Gum, and Rosewood are popular substrates that naturally weather to silver-grey tones. Available in 19mm, 21mm, and 25mm thicknesses for various architectural applications.

Best when…

Immediate weathered silver-grey aesthetic from installation
Consistent colour and texture across entire facade
Eliminates unpredictable natural weathering transition period
Low-maintenance finish — SiOO:X provides 10-15 year protection
BAL-29 compliant with appropriate Australian hardwood substrates
Multiple treatment systems available (SiOO:X, CUTEK, Accoya Color Grey)
Compatible with standard timber cladding installation methods
Natural, non-toxic treatment options (SiOO:X is Red List Free)
Continues to develop authentic patina over time
Multiple Australian hardwood and imported species options

Top advantages

01 Immediate weathered silver-grey aesthetic from installation
02 Consistent colour and texture across entire facade
03 Eliminates unpredictable natural weathering transition period
04 Low-maintenance finish — SiOO:X provides 10-15 year protection
05 BAL-29 compliant with appropriate Australian hardwood substrates

Top limitations

01 Premium pricing over standard timber ($95-350+ AUD/m2 installed)
02 Treatment-dependent performance — SiOO:X, CUTEK, and Accoya have different characteristics
03 Natural greying is uneven without treatment; treatment needed for consistency
04 Batch-to-batch variation possible with natural timber substrates
05 Some treatments require maintenance recoating (SiOO:X every 10-15 years, CUTEK every 3-7 years)

Technical

Physical ·8

Density: 400-1100 kg/m3 Depends on base timber species. Silvertop Ash ~670 kg/m3, Spotted Gum ~1100 kg/m3, Accoya (Radiata Pine) ~510 kg/m3, thermally modified timbers 400-550 kg/m3. Source: Australian Timber Database, Accoya specifications.
Specific gravity: 0.38-1.10 Silvertop Ash 0.62-0.72, Spotted Gum 0.95-1.10, Accoya 0.48-0.53, thermally modified timbers 0.38-0.55. Source: Australian Timber Database.
Porosity: 8-20 % Pre-aging treatment may slightly increase surface porosity on some species. SiOO:X fills surface pores with silica network. CUTEK penetrates and fills internal porosity.
Water absorption: 3-12 % Reduced by treatment. SiOO:X silica network acts as water barrier. CUTEK penetrating oil repels water from within. Accoya acetylation reduces moisture uptake by 75%. Source: Abodo Wood, CUTEK, Accoya.
Hardness: 4.0-11.0 kN Janka hardness depends on species. Silvertop Ash 9.7 kN, Spotted Gum 11.0 kN, Blackbutt 9.1 kN, Accoya ~4.0 kN. Pre-weathering treatment does not significantly affect hardness. Source: Australian Timber Database, Accoya datasheet.
UV resistance: Good to Excellent (treatment dependent) Pre-weathering systems are designed to manage UV exposure. SiOO:X silica network protects underlying timber while allowing controlled surface silvering. CUTEK allows natural UV greying while protecting against moisture damage. Source: Mortlock Timber, Abodo Wood.
Chemical resistance: Moderate to Good (treatment dependent) SiOO:X provides enhanced chemical resistance through silica mineral network. Accoya acetylation improves resistance to acid/alkali conditions. Standard timber has moderate chemical resistance. Source: Abodo Wood, Accoya.
pH tolerance: 4-8 pH Natural timber pH range. Most treatment systems are pH-neutral on cured surfaces.

Mechanical ·5

Tensile strength: 42-125 MPa Depends on base species. Silvertop Ash ~95 MPa, Spotted Gum ~125 MPa, Accoya ~42 MPa (softwood base). Treatment does not affect tensile strength. Source: AS 1720.1, Accoya datasheet.
Compressive strength: 30-70 MPa Parallel to grain. Silvertop Ash ~58 MPa, Spotted Gum ~70 MPa, Accoya ~45 MPa. Source: AS 1720.1, Accoya datasheet.
Flexural strength: 44-130 MPa MOR varies by species. Silvertop Ash ~100 MPa, Spotted Gum ~130 MPa, Accoya ~44 MPa. Source: AS 1720.1, Accoya datasheet.
Impact resistance: 20-70 J/m Depends on species density and grain. Australian hardwoods have high impact resistance. Thermally modified timbers may have reduced impact resistance. Source: species datasheets.
Creep resistance: Good to Excellent Good to Excellent depending on species. Australian hardwoods (Silvertop Ash, Spotted Gum) provide excellent creep resistance. Pre-weathering treatment does not affect structural properties. Source: AS 1720.1.

Sustainability & Health

Embodied carbon & energy ·7

Embodied carbon: -100 to 200 (species and accounting dependent) kg CO2-eq/m3 Timber stores biogenic carbon (~250-900 kg CO2/m3 depending on species). Accoya has published EPD with net negative carbon when biogenic storage included. SiOO:X treatment adds minimal embodied energy. Source: Accoya EPD, WoodWorks.
Carbon footprint: -100 to 200 kg CO2-eq/m3 Potentially carbon-negative when biogenic carbon included. Timber carbon sequestration offsets processing emissions. Long service life (25-50+ years) reduces replacement emissions. Source: timber EPD methodology.
Embodied energy: 400-1500 MJ/m3 Australian hardwood: 400-800 MJ/m3. Accoya: higher due to acetylation process (~1200-1500 MJ/m3). Thermally modified: 600-1000 MJ/m3. Treatment systems add 20-50 MJ/m3. Source: timber EPD frameworks, Accoya EPD.
Water footprint: 40-150 L/kg Forest growth water requirements plus processing. Accoya acetylation process uses acetic anhydride. SiOO:X is water-borne. Source: general timber lifecycle data.
Recycled content: 0 % Typically 0% recycled content (virgin timber). Reclaimed timber can be pre-weathered as restoration technique.
Renewable content: 95-100 % 100% renewable timber substrate. SiOO:X uses plant-based ingredients. CUTEK is oil-based. Accoya uses FSC-certified Radiata Pine. Source: supplier specifications.
Circular score: 8.0 /10 High circular economy value: renewable, long service life, biodegradable at end-of-life. Accoya and SiOO:X treatments are non-toxic enabling composting/biomass recovery. FSC/PEFC sourcing available.

Health & emissions ·1

VOC emissions: <30 ug/m3 SiOO:X: plant-based, water-borne, Red List Free — essentially zero VOC when cured. CUTEK: low-VOC oil formulation. Accoya: 100% non-toxic, no biocides. All systems eliminate need for recurring high-VOC paint/stain maintenance. Source: Abodo, CUTEK, Accoya.

Compliance & Fire

Fire performance ·6

Combustibility class: Combustible — BAL rating per species All timber cladding is combustible. BAL compliance depends on species selection per AS 3959:2018 Appendix F. Pre-weathering treatments do not change combustibility classification. Source: NCC, AS 3959.
Fire resistance level: BAL-19 to BAL-29 (species dependent) minutes BAL ratings per AS 3959:2018 Appendix F — approved species include Silvertop Ash, Spotted Gum, Blackbutt, Red Ironbark, Turpentine, and Merbau for BAL-29. Accoya (Radiata Pine) may not qualify for BAL-29. Source: Sculptform, NCC guidance.
Ignition temp: 280-400 degC Standard timber ignition temperatures. Hardwoods generally higher than softwoods. Silvertop Ash, Spotted Gum, Blackbutt: 300-400 degC. Source: general timber science.
Flame spread index: 75-200 FSI Depends on species density and treatment. Australian hardwoods generally perform better than softwoods. Some SiOO:X products combined with Burnblock fire retardant for enhanced fire performance. Source: Russwood, NCC.
Smoke dev. index: 150-300 SDI Standard timber smoke development. Varies by species density and moisture content.
Heat release rate: 150-400 kW/m2 Typical timber heat release rates. Treatment systems (SiOO:X, CUTEK) do not significantly change fire properties. Fire performance depends on base timber species. Source: NCC guidance.

Cost & Lifecycle

Capex & lead time ·6

Material cost (range): 95-250 AUD/m2 Silvertop Ash: $95-115/m2 supply (species/profile dependent). Accoya Color Grey: $150-250+/m2 supply (premium product, quote-based). SiOO:X treated thermally modified: $120-200/m2 supply. Installation additional $35-65/m2. Overall installed $110-350+/m2. Source: Rustic World Timbers, Nationwide Timber, PY Timber Warehouse, Mortlock Timber.
Material cost (per unit): 5000-13000 AUD/m3 Based on 19mm boards. Silvertop Ash ~$5,000-6,000/m3, Accoya Color Grey ~$8,000-13,000/m3. Calculated from per-m2 pricing.
Lead time: 14-42 days Australian hardwood (Silvertop Ash, Spotted Gum): 14-28 days from local suppliers. Accoya Color Grey: 21-42 days (imported product via Britton Timbers). Thermally modified with SiOO:X: 28-42 days. Source: supplier estimates.
Lifecycle cost: 130-400 AUD/m2 Good lifecycle value due to reduced maintenance. SiOO:X treated timber: lower recoating frequency. Accoya: 50-year warranty reduces replacement costs. Natural grey species: lowest upfront but higher maintenance. Source: supplier lifecycle data.
Annual maintenance: 0.50-3.00 AUD/m2/year SiOO:X: recoat ~$15-20/m2 every 10-15 years = ~$1-2/m2/year. CUTEK: recoat ~$10-15/m2 every 5-7 years = ~$1.50-3/m2/year. Accoya Color Grey: minimal maintenance, ~$0.50-1/m2/year. Source: Abodo, CUTEK, Accoya.
Market availability: Good — multiple suppliers and treatment options Silvertop Ash: widely available from multiple Australian suppliers (Rustic World Timbers, Nationwide Timber, Timber & Rose, PY Timber Warehouse). Accoya: distributed by Britton Timbers (Australian authorised distributor), stocked by Canterbury Timbers (Sydney), Austim (Perth). SiOO:X: available through Mortlock Timber and Abodo dealers. Source: supplier websites.

Service life & durability ·3

Expected lifespan: 25-50 years Silvertop Ash (Durability Class 2): 15-40 years above ground. Spotted Gum (Durability Class 1): 40-80 years. Accoya: 50+ years above ground. Thermally modified timber: 25-40 years. Source: Australian Timber Database, Accoya.
Maintenance interval: 5-15 years SiOO:X: recoat after 10-15 years (cladding). CUTEK: recoat every 3-7 years (vertical cladding less frequent than horizontal). Accoya Color Grey: minimal maintenance — through-core colouring means surface wear does not reveal different colour. Source: Abodo Wood, CUTEK, Accoya.
Warranty period: 10-50 years Accoya Color Grey: 50-year above-ground, 25-year in-ground warranty. SiOO:X coating: typically 10-15 years. Silvertop Ash (natural): no treatment-specific warranty. Source: Accoya, Abodo Wood.

Layer D

Where it's used

External wall cladding systems

Feature walls and accent panels

Screening and privacy applications

Soffit and ceiling linings

Commercial and residential architecture

Coastal and bushland environments

Contemporary and modernist design

Renovation and retrofit projects

Where it's used

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