Kempas (Koompassia malaccensis) in numbers: hardness, weight, strength, shrinkage, movement and decay resistance, taken from the tables of the USDA Forest Products Laboratory’s Wood Handbook, followed by what the wood is like to work and what it is used for. The values are averages from small, clear, straight-grained test specimens; real boards with knots, sloping grain or a different moisture content will differ.
| Property | Kempas |
|---|---|
| Janka side hardness, 12% moisture | 1,710 lbf (7,606 N) |
| Janka side hardness, green | 1,480 lbf |
| Hardness rank | harder than 135 of the 168 woods with a 12% hardness value in our database |
| Density at 12% moisture | 55.0 lb/ft³ (880 kg/m³)† |
| Weight per board foot (12%) | 4.58 lb† |
| Specific gravity (ovendry weight, green volume) | 0.71 |
| Specific gravity at 12% moisture | 0.79† |
| Bending strength (modulus of rupture), 12% | 17,700 psi |
| Stiffness (modulus of elasticity), 12% | 2.69 million psi |
| Crushing strength (compression parallel to grain), 12% | 9,520 psi |
| Shrinkage green to ovendry: radial / tangential / volumetric | 6.0% / 7.4% / 14.5% |
| Tangential / radial shrinkage ratio | 1.23 |
| Dimensional change per 1% moisture (radial / tangential) | not reported |
| Heartwood decay resistance | resistant |
What it is
Kempas (Koompassia malaccensis) grows throughout the lowland forests of Malaysia and Indonesia, often in rather swampy areas. Freshly cut heartwood is brick red; on exposure to air it darkens to orange-red or red-brown with many yellow-brown streaks, caused by the soft tissue (axial parenchyma) around the pores.
The texture is rather coarse and the grain is typically interlocked. Kempas is a hard, heavy wood, and in North America it is best known as an imported flooring species.
Working properties
Kempas is difficult to work with hand and machine tools because of its hardness and interlocked grain. It dries well, with some tendency to warp and check. Pre-drill for nails and screws, and use carbide blades.
The heartwood resists decay fungi (resistant class in Table 14-1) but is vulnerable to termites. Unlike many dense tropical woods, it treats readily with preservatives; the Handbook reports very high retentions. Tangential shrinkage is about 7.4% from green to ovendry, so flooring needs proper acclimatisation.
Weight and density
At 12% moisture content kempas weighs about 55.0 lb per cubic foot (estimated from its specific gravity and shrinkage), so one board foot (144 cubic inches) weighs about 4.58 lb. An 8 ft board of actual size 3/4 × 5-1/2 in. (a 1×6) holds 0.229 cubic feet and weighs about 12.6 lb; an 8 ft piece 1-1/2 × 3-1/2 in. (a 2×4 size) weighs about 16.0 lb. Green wood is much heavier because of the water it holds.
Density here is ovendry weight plus 12% water, divided by volume at 12% moisture content (Wood Handbook Eq. 4-12: density = specific gravity at 12% × 62.43 lb/ft³ × 1.12).
How it compares
| Species | Janka (lbf) | Density (lb/ft³) | Bending (psi) | Stiffness (Mpsi) | Tangential shrink (%) | Decay resistance |
|---|---|---|---|---|---|---|
| Kempas | 1,710 | 55.0† | 17,700 | 2.69 | 7.4 | resistant |
| Courbaril (jatoba) | 2,350 | 53.8* | 19,400 | 2.16 | 8.5 | resistant |
| Jarrah | 1,910 | 54.0† | 16,200 | 1.88 | 11.0 | very resistant |
| Keruing | 1,270 | 53.4* | 19,900 | 2.07 | 10.9 | moderately resistant |
| Northern red oak | 1,290 | 44.1 | 14,300 | 1.82 | 8.6 | slightly or nonresistant |
| Sugar maple | 1,450 | 44.1 | 15,800 | 1.83 | 9.9 | slightly or nonresistant |
Uses
The Handbook calls kempas ideal for heavy construction work, railroad crossties and flooring. Strip and parquet flooring is the main use in the export trade.
Frequently asked questions
How hard is kempas flooring?
The Wood Handbook gives kempas a Janka side hardness of 1,710 lbf (7,606 N) at 12% moisture content, about 1.3 times that of white oak and harder than hard maple.
Does kempas darken?
Yes. It is brick red when cut and darkens to orange-red or red-brown with yellow-brown streaks on exposure to air and light.
Is kempas termite resistant?
No. The heartwood resists decay fungi but is vulnerable to termites, according to the Handbook.
How heavy is kempas?
About 55.0 lb per cubic foot at 12% moisture content, or 4.58 lb per board foot.
Sources
- USDA Forest Products Laboratory. Wood Handbook: Wood as an Engineering Material. General Technical Report FPL-GTR-190, 2010. Chapter 2 (species descriptions), Chapter 4 (Tables 4-3, 4-4 shrinkage; Eq. 4-7, 4-9, 4-12 density), Chapter 5 (Tables 5-3b, 5-5b strength and hardness), Chapter 13 (Table 13-5 dimensional change coefficients), Chapter 14 (Table 14-1 decay resistance)
- USDA Forest Products Laboratory. Wood Handbook, 2021 edition (FPL-GTR-282)
Last reviewed: 24 October 2026. Numbers are generated from our parsed copy of the Handbook tables, so every page uses the same data. Values marked * are estimates computed with the Handbook’s own equations. Spotted an error? Please let us know.