Paint Quantity for NZ Cladding Systems
Generic paint calculators use averaged spread rates that don't account for the significant differences between NZ cladding materials. Rough-sawn pine and smooth Hardiplank consume very different volumes of primer and topcoat.
NZ Cladding Spread Rates
Spread rates (m² per litre) vary by surface porosity and texture. These are based on Resene and Dulux NZ trade data sheets:
| Surface | Primer | Topcoat (per coat) |
|---|---|---|
| Rough-sawn pine weatherboard | 6 m²/L | 10 m²/L |
| Smooth bevel-back / cedar | 8 m²/L | 12 m²/L |
| Hardiplank (factory primed) | Touch-up only | 10 m²/L |
| Plaster / texture coat | 10 m²/L | 10 m²/L |
| Concrete block | 5 m²/L | 8 m²/L |
| GIB board (interior) | 12 m²/L | 12 m²/L |
Hardiplank System Notes
James Hardie Hardiplank comes factory-primed. For new installations, only touch-up priming of cut ends and fixing points is required — not a full primer coat. Two topcoats of an approved acrylic paint system then complete the system. Hardie recommends specific approved paint products — check jameshardie.co.nz for the current approved products list.
Coastal and Geothermal Areas
For properties within 500m of the coast or in geothermal zones (Rotorua area), use a paint system specifically rated for high-corrosion environments. Both Resene and Dulux have specific products for these conditions — standard exterior acrylic will degrade much faster.
Primer Selection
- Bare pine: Resene Wood Primer or Dulux Weathershield Primer Sealer
- Hardiplank cut ends: Hardie Primer (specifically formulated for fibre cement)
- Plaster: alkali-resistant primer (standard acrylics can saponify on fresh plaster)
- Concrete: concrete sealer / block filler before topcoat