How do you build a strong popsicle stick bridge?

Short answer: use a truss rather than a flat stack, make members deeper by laminating sticks where the rules allow it, keep every glue joint tight and thin, and brace long members against buckling.

Why craft sticks are different

A craft stick is wide and thin. It is stiff when loaded along its length through the flat, but easy to bend across its thin side, and it splits along the grain. Good designs use the stick the way it is strong.

Tips

1. Use a truss. Triangles turn the sticks into straight pushes and pulls. See truss basics.
2. Laminate where allowed. Gluing two or three sticks face to face makes a member that is thicker and much harder to buckle. Check whether built-up members are allowed and whether glue is limited, and note that laminating adds glue weight.
3. Overlap, don't butt. A joint where sticks overlap along their faces is stronger than one where ends are pushed together. See gluing joints.
4. Keep glue thin. A thick bead is weak and heavy. Wipe off the squeeze-out.
5. Clamp or pin while it sets, and wait for the glue to cure. See drying times.
6. Brace long members so they can't bow sideways.
7. Build flat on a plan so both sides match.

Check the rules

Some craft-stick contests supply the sticks and the glue, some limit the number of sticks, some ban glue entirely, and some set a build time on site. See on-site builds and other materials.

Our strength figures are for balsa, not craft sticks, so test your own.