What Happens When You Foam a Metal Roof in Phoenix?
This article is adapted from Mikel Wallesen's video above.
Read the video transcript
Here in Phoenix, it was 105 degrees out the day we shot this, and if you've ever touched a metal roof in the middle of an Arizona summer, you already know what we're dealing with. Before we did anything to this roof, we put the temp gun on it and it read 153 degrees. That's the surface of the metal, just sitting there cooking in the sun.
That kind of heat doesn't just stay on the roof. It pushes straight down into the building, runs your AC nonstop, and shortens the life of the metal itself. So let's walk through what actually happens when we spray foam over it.
Step One, The Bare Metal at 153 Degrees
Metal is a great conductor, which is exactly the problem in Phoenix. The sun hits the panel, the panel heats up almost instantly, and then it dumps that heat into whatever is underneath. Warehouses, shops, patios, it doesn't matter, the inside follows the roof.
That 153 degree reading isn't unusual either. On a real summer afternoon out here, we see metal roofs hit 160 plus all the time.
Step Two, Spray Foam Knocks It Down to 132
Once we sprayed the closed cell polyurethane foam over the panels, we hit the same spot with the temp gun and it read 132. That's roughly a 20 degree drop just from the foam itself.
Foam works because it's an insulator, not a conductor. Instead of letting heat pass through, it traps it at the surface and slows it way down before it ever reaches the metal or the building below. It also seals every seam, screw, and lap on the roof at the same time, so you stop the leaks and the heat in one shot.
Step Three, White Coating Drops It Another 9 Degrees
After the foam cured, we rolled on the white elastomeric coating. Same temp gun, same spot, and now we're sitting at 123 degrees. From bare metal at 153 down to 123 with the coating on, that's about a 30 degree total drop on the roof surface.
The white coating does two jobs. It protects the foam from UV, which is the main thing that breaks foam down out here, and it reflects sunlight instead of absorbing it. That reflectivity is where the second temperature drop comes from.
Why That 30 Degrees Actually Matters
A 30 degree cooler roof means a cooler building, a smaller load on the AC, and a longer life out of everything up there. Owners we've done this for usually notice the power bill before they notice anything else.
On top of the energy side, you're also getting a fully sealed roof with no exposed fasteners, no open seams, and a system you can recoat down the road instead of tearing it off.
If you've got a metal roof in the Phoenix area that's been baking your building all summer, give us a call and we'll come out, put the temp gun on it, and walk you through what foam would do for you.
