Balsa vs basswood for a bridge: what's the difference?
How the two woods compare in weight, strength, cutting and gluing, and why the contest's rules and mass limit decide which one you use.
Updated · 1 min read
Short answer: basswood is heavier, stiffer and stronger than balsa, but balsa is far lighter for its strength and much easier to cut. Contests choose one or the other, so use the one in your rules.
| Balsa | Basswood | |
|---|---|---|
| Weight | very light | noticeably heavier |
| Strength | lower in absolute terms, very high for its weight | higher in absolute terms |
| Cutting | easy with a hobby knife | harder, needs a sharp blade and more force |
| Splitting | crushes and dents easily | tougher, but can split along the grain |
| Used in | many school and university contests | some regional engineering challenges |
What changes in your design
- Mass limits are set for the material. A basswood limit is higher than a balsa one.
- Joints are more of a challenge in basswood, since cuts are harder to make accurate.
- Dents and crushing are less of a worry in basswood.
The numbers on this site are balsa only, so don't apply them to basswood. The ideas, such as truss shape, buckling and good joints, carry across. See other materials.