Iroko
Milicia excelsa · hardwood · West Africa · low movement
- Janka hardness 1,260 lbfred oak ≈ 1,290 lbf
- Density ≈ 46 lb/ft³specific gravity 0.66 at 12% MC
- Shrinkage — tangential 3.8%flatsawn width, green → ovendry
- Shrinkage — radial 2.8%quartersawn width
- T/R ratio 1.4 : 1higher = more cupping in flatsawn stock
Shop notes "African teak" — the smallest movement numbers on this list, weather-hardy, and far cheaper than teak. Occasional calcium deposits will chip an edge.
Seasonal movement at a glance
Width change for iroko across a typical indoor year — 6% moisture content in the heated winter to 12% in a humid summer:
| Board width | Flatsawn | Quartersawn |
|---|---|---|
| 6″ | 1/16″ (0.049″) | 1/32″ (0.036″) |
| 12″ | 3/32″ (0.098″) | 1/16″ (0.072″) |
| 24″ | 3/16″ (0.195″) | 5/32″ (0.144″) |
| 36″ | 9/32″ (0.293″) | 7/32″ (0.216″) |
Run your own numbers
Different width, different climate swing — the calculator below is preset to iroko:
Typical swings:
Iroko questions
How much does iroko move with the seasons?
A 12″-wide flatsawn iroko board moves about 3/32″ across a typical indoor swing from 6% to 12% moisture content; quartersawn, about 1/16″. Its tangential shrinkage is 3.8% and radial 2.8% (green to ovendry) — a low-movement wood.
How hard is iroko?
Iroko rates about 1,260 lbf on the Janka scale — in red oak’s hardness neighborhood (red oak is roughly 1,290 lbf). Density runs about 46 lb/ft³ at indoor moisture levels.
Is iroko good for wide panels and tabletops?
Yes, with normal precautions: its 1.4:1 tangential-to-radial ratio is unusually balanced, so panels stay flatter than most. Still fasten solid tops so they can move across their width.
Similar species
Yellow Birch · Northern Red Oak · American Beech · Black Oak · White Ash · Green Ash
Shrinkage, specific gravity, and hardness from the Wood Handbook, FPL-GTR-282 (2021 edition), USDA Forest Products Laboratory (public domain). Values are species averages — individual boards vary with growth conditions and how they were dried.