Form · 450 mm
Plant-Based Fibre — indicative fig. O·11
Fire A1 when rendered to AS 1530.1 Non-combustibleEmbodied carbon -0.35kgCO₂e/kg Stores carbonCompressive 0.05-0.9 MPa (unrendered), 1.7-6.0 MPa (rendered)MPa StructuralDesign life 50yr
Highly insulating natural building material with R-value 4.8-9, excellent fire resistance (FRL 90-90-90 when rendered), suitable for all Australian climate zones and BAL ratings. Requires Performance Solution for NCC compliance.
01 Physical
Density 90-110 kg/m³ (typical construction grade)kg/m³
Specific gravity 0.09-0.11
Porosity 85-90%%
Water absorption <15% moisture content required for construction%
Hardness N/A - compressible material
UV resistance Poor - requires protective render
Chemical resistance Moderate - alkaline compatible
pH tolerance pH 6-9 optimal
Surface roughness N/A - covered by renderµm
02 Mechanical
Tensile strength 0.01-0.02 MPa (perpendicular to straw)MPa
Compressive strength 0.05-0.9 MPa (unrendered), 1.7-6.0 MPa (rendered)MPa
Flexural strength Dependent on render - typically 0.5-2.0 MPaMPa
Shear strength 0.02-0.05 MPaMPa
Poisson's ratio 0.1-0.2 (varies with orientation)
Impact resistance High - flexible response
Creep resistance 20-80mm settlement typical under compression
03 Thermal
Thermal conductivity 0.038-0.08 W/m·K (varies with density and orientation)W/m·K
Specific heat 1600 J/kg·KJ/kg·K
Thermal expansion Negligible - accommodated by compression×10⁻⁶/°C
04 Compliance & Fire First question
Combustibility class Non-combustible when rendered to AS 1530.1
Fire resistance level FRL 90/90/90 (rendered)
Ignition temp >300°C°C
Flame spread index 0 (rendered surface)
Smoke dev. index 0-3 (rendered)
Heat release rate Minimal - oxygen-starved environment
05 Sustainability & Health
Embodied carbon -0.35 to -0.91 kg CO₂e/kg
Carbon footprint -1.35 kg CO₂/kg (sequestered)
Embodied energy 0.91 MJ/kg (baling and transport)MJ/kg
Water footprint Variable - dependent on crop irrigationL/kg
Recyclability 100%%
Recycled content 0% (agricultural by-product)%
Renewable content 100%%
Circular score Excellent - full biodegradability
VOC emissions Zero
Toxicity rating Non-toxic
LEED contribution Multiple credits possible
06 Durability · Cost · Logistics
Expected lifespan 50-100+ years with maintenance
Maintenance interval Annual inspection, 5-10 year render touch-ups
Warranty period Builder-dependent, typically 6-7 years
Material cost (range) $3-8 per bale
Material cost (per unit) $35-50/m² (wall area, bales only)
Lead time 2-8 weeks depending on season
Lifecycle cost Lower than conventional due to energy savings
Annual maintenance $50-200/year (render maintenance)
Market availability Seasonal - harvest dependent
07 Assessment
Advantages
- Exceptional thermal insulation (R-value 4.8-9)
- Fire resistant when rendered (FRL 90-90-90)
- Carbon negative with sequestration
- Low embodied energy (<50MJ/m²)
- Excellent acoustic insulation
- Breathable wall system
- Agricultural waste utilisation
- Suitable for owner-builder construction
- Non-toxic, no VOC emissions
- Locally available across grain-growing regions
Constraints
- Requires Performance Solution for NCC compliance
- Moisture sensitive - needs careful detailing
- Labour-intensive construction
- Thick walls reduce internal floor area
- Limited experienced contractors
- Requires protective render system
- Not suitable for wet areas without special details
- Settlement requires pre-compression
- Transport bulky despite light weight
- Maintenance of render required
08 Applications
A1 Residential external walls (single and double storey)
A2 Bushfire-resistant construction (all BAL ratings)
A3 Passive solar design thermal mass walls
A4 Acoustic insulation walls
A5 Agricultural and storage buildings
A6 Community and educational facilities
A7 Heritage-compatible natural building
A8 Off-grid and remote area construction
09 Sources & Standards
Sources pending — citations for this material are not yet recorded. Verify all figures against manufacturer data and current standards before specifying.