Sweet birch
Betula lenta
Sweet birch measures 1,470 lbf on the Janka scale, 14% harder than northern red oak.
- Of the three birches in the handbook, none is harder, heavier or stiffer, and none has a higher T/R ratio.
- Across all 155 woods it falls in the top fifth for stiffness, radial shrinkage and volumetric shrinkage and in the bottom fifth for T/R ratio.
- On the Janka scale its nearest neighbours are willow oak at 1,460 lbf and pin oak at 1,510 lbf.
U.S. hardwoodsU.S. softwoodsImported woodsNorthern red oak
Six measures
Sweet birchU.S. hardwoods medianOther woods
Cupping tendency
1.3812th lowest of 15527% below the U.S. hardwoods median1.092.90Stiffness
2.17 M psi15.0 GPa28th stiffest of 15536% above the U.S. hardwoods median0.54 M psi4.06 M psiBending strength
16,900 psi116.5 MPa37th strongest of 15530% above the U.S. hardwoods median4,300 psi29,900 psiJanka hardness
1,470 lbf6,539 N39th hardest of 1558th of 53 U.S. hardwoods; 27% above the U.S. hardwoods median240 lbf3,680 lbfDensity
0.600.65 at 12% MC39th heaviest of 1550.250.96Shrinkage across the face
9.0%radial 6.5%42nd highest of 1553.5%12.7%
How much it moves
The two directions move almost alike (T/R 1.38), so flatsawn and quartersawn boards differ by only 0.15 in.
0.54 in.
off a 6-inch flatsawn board, green to oven-dry
- Tangential
- 9.0%
- Radial
- 6.5%
- Volume
- 15.6%
- T/R ratio
- 1.38 (12th most stable of 155)
End view, shrinkage drawn 3× life size.
Closest substitutes
- Yellow birch
14% softer · 8% lighter · shrinks 0.5 points more across the face
- Manni
24% softer · 3% lighter · shrinks 0.7 points more across the face
- Angelique
12% softer · same density · shrinks 0.2 points less across the face
Among the birches
1st hardest of 3, lbf.
Laboratory values
Its most unusual laboratory figure is tension across the grain: 3rd highest of the 73 woods with a published value.
| Property | Green | Dry, 12% MC | Change when dried | Metric, 12% MC |
|---|---|---|---|---|
| Tension perpendicular | 430psi | 950psi | +121% | 6.60MPa |
| Impact bending | 48in. | 47in. | −2% | 1,194mm |
| Shear parallel to grain | 1,240psi | 2,240psi | +81% | 15.4MPa |
| Work to maximum load | 15.7in-lbf/in³ | 18in-lbf/in³ | +15% | 124.1kJ/m³ |
| Modulus of elasticity | 1.65M psi | 2.17M psi | +32% | 15.0GPa |
| Compression perpendicular | 470psi | 1,080psi | +130% | 7.40MPa |
| Modulus of rupture | 9,400psi | 16,900psi | +80% | 116.5MPa |
| Compression parallel to grain | 3,740psi | 8,540psi | +128% | 58.9MPa |
| Side hardness | 970lbf | 1,470lbf | +52% | 6,539N |
Wood Handbook Table 5-3b, Table 4-3. Data & method · Guides