Profiles · 19–21 mm
Timber — indicative fig. O·19
Australian native hardwood cladding with excellent bushfire resistance (BAL-29), moderate durability, and distinctive brown colouring with pink tinge. Suitable for external cladding in bushfire-prone areas.
01 Physical
Density null
02 Mechanical
Compressive strength null
03 Thermal
Thermal conductivity null
04 Compliance & Fire First question
Fire resistance level null
05 Sustainability & Health
Carbon footprint null
06 Durability · Cost · Logistics
Expected lifespan null
Material cost (range) null
07 Assessment
Advantages
- organic material benefits
Constraints
- High density (~950–1100 kg/m³) — heavier than most hardwood cladding species; long boards require two-person installation and robust fixing systems
- Very high Janka hardness (11.0 kN) — among the hardest Australian cladding timbers; carbide tooling essential, nail-gun pre-boring required to avoid splitting
- Durability Class 2 per AS 5604 — lower than Blackbutt Class 1; above-ground external use only without treatment; periodic recoating critical for longevity
- Prone to surface checking in exposed conditions — interlocked grain and high density create tension during drying; boards can develop visible surface cracks within 1–2 seasons
- Supply cost $90–200/m² installed — premium hardwood pricing similar to Blackbutt; limited plantation availability means supply depends on native forest sourcing
- BAL-29 compliant per AS 3959 but combustible — not suitable for BAL-40 or BAL-FZ zones without additional fire protection; verify with certifier for site-specific BAL assessment
- Limited profile availability compared to mainstream species — fewer suppliers stock 21mm Silvertop Ash in full range of profiles (rebated, shiplap, square-edge)
- External maintenance required every 2–3 years (oil or penetrating stain) — untreated surfaces weather to silver-grey with surface checking and potential fungal staining
- Regional availability concentrated in NSW/VIC alpine regions — project logistics and lead times add cost for other states
08 Applications
A1 organic applications
09 Sources & Standards
Sources pending — citations for this material are not yet recorded. Verify all figures against manufacturer data and current standards before specifying.