What wood do bridge contests use besides balsa?
Basswood, popsicle sticks, ice-cream sticks and toothpicks: which contests use them, how they differ from balsa, and what to check in your rulebook.
Updated · 2 min read
Short answer: balsa is the most common material for student bridge contests, but not the only one. Others use basswood, craft sticks (popsicle sticks), ice-cream sticks or toothpicks. Always build with the material your rulebook names.
The common alternatives
- Basswood. A denser, stiffer, stronger wood than balsa, used by some regional engineering challenges for trusses. It is heavier, so mass limits are set differently. It cuts less easily with a hobby knife.
- Popsicle or craft sticks. Flat, thin sticks, commonly about 4.5 in long and 3/8 in wide, sold in bags. Used by contests run by engineering societies and universities in North America, India, Brazil and elsewhere. Often paired with white (PVA) glue.
- Ice-cream sticks. Similar to popsicle sticks, and used in some contests where bridges must be built without glue and held together by interlocking joints.
- Toothpicks. Used in some section-level toothpick bridge challenges, usually with a glue specified by the rules.
How they differ from balsa
| Balsa | Basswood | Craft sticks | |
|---|---|---|---|
| Weight | very light | heavier | medium |
| Strength for its weight | very high | good | modest |
| Cutting | easy | harder | splits along the grain |
| Typical shape | square sticks | strips and sticks | flat thin sticks |
Craft sticks are flat and thin, so they bend and buckle easily across their thin side, and they split along the grain. Designs that work for square balsa sticks may need to be adapted, for example by stacking sticks into deeper members where the rules allow it.
Check the rules
Contests often specify the exact stick size, the glue and sometimes the supplier, and they may supply the material on the day. See reading your rulebook.
A note about our numbers
The strength figures on this site are for balsa. We haven't sourced equivalent numbers for basswood or craft sticks, so don't apply the balsa figures to them. The general ideas, such as how a truss works and why compression members buckle, apply to any material.