LACRYSIL fire-rated professional polyurethane foam is a one-part gun foam with fire class B1, meaning a material of low flammability. The joint does not sustain burning on its own and slows fire passing through the opening. The foam is red, so on site it is clear where a fire-rated joint is and it does not get replaced with ordinary foam during repairs.

Where it is used

Installing window and door frames, including fire doors, sealing pipe and cable penetrations through walls and floors, and filling joints in assemblies with a specified fire resistance. Class B1 applies to the foam itself. For fire doors, escape exits and service penetrations through fire walls the design usually requires this class. The fire resistance of the assembly is set by the design, and the foam is only one part of it.

Working properties

Post-expansion is 150–250 %, so the joint is filled about halfway. The maximum joint depth is 30 mm. The foam is tack-free in 5–30 minutes, hardens in 3–6 hours and fully cures in 24 hours, so plan the job with that time in hand. Apply at +10…+35 °C and keep the can at +15…+30 °C before use. The 800 ml can works only with a gun; shelf life is 18 months. Fresh foam is removed from the gun and tools with foam cleaner.

Questions and answers

Can the joint be left exposed?

No. Like any polyurethane foam it breaks down in UV light, so the joint is covered.

Can it be used in winter?

Only from +10 °C. For lower temperatures there is standard professional foam, but it does not carry class B1.

What other gun foams are there?

They are all listed on the “Gun-grade expanding foam” page.