What Happens When You Spray Foam a Metal Roof

Why metal roofs run hot

Metal doesn't insulate. It transfers. Whatever temperature the sun makes the surface, the inside of that building is fighting to stay ahead of it.

On a job we just finished in North Scottsdale, the roof surface was reading 125 to 135 degrees, and that heat was pouring straight into the building underneath it. That's the part nobody thinks about until they're standing inside a metal building in July.

What actually stops it

Spray polyurethane foam. On this job, we put down two inches of it, direct to the metal.

Foam doesn't reflect heat, it stops it from moving at all. Two inches gives you a real thermal break between the sun and the ceiling. That's the whole trick, stop the transfer, not just the surface temperature.

On top of the foam, we ran an EC 100 base coat, and finished with a white, high-reflective top coat. The white coat handles the sun hitting the surface. To see the last step up close, read why we spray the final coat on a spray foam roof slowly. The foam underneath it handles everything that gets through anyway. Two different jobs, both need to happen.

Why this matters more in Arizona than almost anywhere

Every degree the roof sheds is a degree the AC isn't fighting. On a metal building running 125+ on the roof surface, that adds up fast, in comfort and in the electric bill.

The bottom line

If your building has a metal roof and it feels like an oven in there, the roof surface is why. Paint alone won't fix it. Foam underneath a reflective coat does.

That's the job. Nothing complicated about it, it just has to be done right.