Kapur — Dryobalanops spp.
A red-toned SE Asian hardwood from the rainforests of Borneo and Malaysia. Class 2 above-ground durability, distinctive camphor-like aroma when freshly cut, and a long history in external joinery, decking and door/window sills. Prized for dimensional stability and its ability to weather to a soft warm grey if left untreated.
Kapur products
Decking and battens in stock, with cladding, flooring, lining, structural and joinery sections supplied to order. Class 2 above-ground durability, low-shrinkage SE Asian hardwood.
Technical ReferenceSummary
Kapur (Dryobalanops spp., principally D. aromatica) — also known as Borneo Camphorwood, Keladan and Kapoer — is a tropical SE Asian hardwood from the lowland rainforests of Malaysia and Indonesia. The timber gets its name from its distinctive camphor-like odour when freshly cut.
Heartwood is classified Class 2 — Durable for above-ground use (15–40 years per WoodSolutions, AS 5604). Density 750 kg/m³ air-dry. Strength SD4 seasoned (S3 unseasoned), Joint JD2 seasoned (J2 unseasoned), F-grade F22 seasoned. The species is not Lyctus-susceptible but is not termite-resistant — H-class treatment is required for termite-prone applications. Marine borer resistance is low. Suitable for BAL 12.5 and 19 bushfire zones. One critical fastener note: Kapur reacts with iron fasteners and develops an unsightly black stain. Use stainless steel or hot-dipped galvanised fixings only.
Class 2 of 4
Character & Appearance
Heartwood is red to reddish-brown with sapwood almost white to light yellowish-brown. Grain is variable — straight to spiral to deeply interlocked depending on growing conditions and the cut. Texture is moderately coarse to even. Fresh cut surfaces release a distinctive camphor-like aroma — the basis of one of the species' common names, Borneo Camphorwood.
Left untreated, Kapur weathers to a soft warm grey — a finish often used intentionally for landscape and external joinery applications. With oiling, the natural reddish-brown colour can be preserved indefinitely.
Species & General Properties
Mechanical & Physical Properties
| Property | Unseasoned | Seasoned |
|---|---|---|
| Density | 1,100 kg/m³ | 750 kg/m³ |
| Janka hardness | 4.8 kN | 6.0 kN |
| Modulus of rupture (bending) | 82 MPa | 132 MPa |
| Modulus of elasticity | 16 GPa | 21 GPa |
| Maximum crushing strength | 46 MPa | 73 MPa |
| Strength Group | S3 | SD4 |
| Stress Grade (typical, Structural No.1) | F17 | F22 |
| Joint Group | J2 | JD2 |
| Shrinkage (Total) | Value |
|---|---|
| Tangential shrinkage | 6.00 % |
| Radial shrinkage | 2.50 % |
| Unit movement — tangential | 0.37 % |
| Unit movement — radial | 0.19 % |
Recommended Applications
Kapur's combination of Class 2 durability, moderate density, low shrinkage and good machining properties makes it particularly well-suited to external joinery applications — it has been a preferred species for door and window sills, frames and exterior trim for decades.
Specification Notes
- Natural durability ratings apply to heartwood only. Sapwood (almost white to yellowish-brown) is not naturally durable.
- Recommended spec wording: "Kapur (Dryobalanops spp.) heartwood — AS 5604 Class 2 above-ground durability, Strength Group SD4 seasoned, Joint Group JD2 seasoned, F-grade F22 seasoned."
- Fastener compatibility: Kapur develops an unsightly black stain in contact with iron nails, screws or fittings. Use stainless steel or hot-dipped galvanised fixings only.
- Termite resistance: not resistant. H-class treatment required where AS 3660 termite barriers are required.
- Lyctus: not susceptible — no Lyctus treatment required.
- Finishing: Kapur can be left untreated to weather naturally to a soft warm grey — a recognised aesthetic for landscape applications. For colour retention, oil within 2 weeks of install and re-oil 12-monthly.
- Bushfire performance: BCA Group 3 when applied as veneer ≤0.85mm on a substrate ≥12mm. Approved under AS 3959 for use in BAL 12.5 and 19 bushfire-prone zones.
References
Speccing Kapur for a project?Kapur for a project?
Decking and battens in stock — cladding, flooring, lining, structural and joinery supplied to order from our SE Asian supply chain. All material from legal and traceable sources.