Why Does Spray Foam Shrink

This is due to either an improper ratio of chemicals in on-site mixing, improper amount of spray foam applied at a given time, or poorly prepared surfaces (dust, damp) – or some combination of the three.

Why is my spray foam not expanding?

Most of the time, using an old can of foam will result in lackluster performance—the foam will not expand to its typical size, or its components will be sticky and drippy and not expand as intended. In rare cases, using an expired can of expanding foam may present a risk of explosion.

Does water stop expanding foam?

Expanding polyurethane foam sealant requires moisture to expand and cure. If you’re applying foam to dry wood or other dry surfaces, or working on a day with little humidity, misting the area first will help the foam expand and cure faster. Be careful, though; you want to dampen the area, not wet it.