Northern Catalpa
Catalpa speciosa · hardwood · Eastern North America · low movement
- Janka hardness 550 lbfred oak ≈ 1,290 lbf
- Density ≈ 29 lb/ft³specific gravity 0.41 at 12% MC
- Shrinkage — tangential 4.9%flatsawn width, green → ovendry
- Shrinkage — radial 2.5%quartersawn width
- T/R ratio 2.0 : 1higher = more cupping in flatsawn stock
Shop notes One of the most stable domestic hardwoods — kiln-to-shop drama is rare. Soft, ring-porous, rot-resistant; lovely for carved signs and outdoor trim.
Seasonal movement at a glance
Width change for northern catalpa 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″ (0.063″) | 1/32″ (0.032″) |
| 12″ | 1/8″ (0.126″) | 1/16″ (0.064″) |
| 24″ | 1/4″ (0.252″) | 1/8″ (0.129″) |
| 36″ | 3/8″ (0.378″) | 3/16″ (0.193″) |
Run your own numbers
Different width, different climate swing — the calculator below is preset to northern catalpa:
Typical swings:
Northern Catalpa questions
How much does northern catalpa move with the seasons?
A 12″-wide flatsawn northern catalpa board moves about 1/8″ across a typical indoor swing from 6% to 12% moisture content; quartersawn, about 1/16″. Its tangential shrinkage is 4.9% and radial 2.5% (green to ovendry) — a low-movement wood.
How hard is northern catalpa?
Northern Catalpa rates about 550 lbf on the Janka scale — soft enough to dent in daily use (red oak is roughly 1,290 lbf). Density runs about 29 lb/ft³ at indoor moisture levels.
Is northern catalpa good for wide panels and tabletops?
Yes, with normal precautions: its 2.0:1 tangential-to-radial ratio is moderate. Still fasten solid tops so they can move across their width.
Similar species
American Chestnut · Yellow-Poplar (Tulipwood) · Red Alder · Spanish Cedar · Butternut · Sassafras
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.