Spray foam surface temperatures
rhl_
| Posted in Green Products and Materials on
Hi,
I’m finally fixing this:
https://www.greenbuildingadvisor.com/article/untangling-roof-insulation-goof
As I’ve posted in the past I’m very weary of spray foam.
I’m warming up to it though. Unfortunately the weather is not.
I am on a time budget though, and the ceiling is now open.
I know you need 50-80 deg substrate temperatures to apply the foam.
Can this be reasonably achieved with diesel heaters in a 10×15 room? Outdoor air temperature on install day likely to be in the 30s.
We can crank the temperature on the tstats and run a space heater the night before..
best,
-rhl
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Replies
Your installer should use low temperature SPF mix. This can be installed over bellow freezing surfaces. Make sure this is the case, installing the wrong mix can create issues. You can check the PDF of the proposed compound to see install temperature ranges.
Getting the room hot is not the same as getting the surface hot, you'll have a hard time getting the roof deck hot enough to install the warm weather mix.
If you have to do it now, low temperature mix helps. I don't entirely trust it though, similar to "low temperature" concrete mixes. It's best to wait until you get warmer weather if you can. You only need the substrate up over 50F during applicaiton and the intial cure, which is a matter of a few hours or so max usually (depending on how long it takes to apply the spray foam).
Heaters won't really work. If you were right on the edge (substrate at 48F or something), it might be enough, but otherwise you're not really accomplishing much with the heaters.
Bill
This went in around 35-40. I haven’t seen any problems
https://youtu.be/6RemIxQouLs
You may have gotten lucky, or may have had other conditions (like moisture content) just right. When the temperature is too far off, spray foam curing can be a problem, and that's usually where horror stories come from (although I think the more common issue is the installer didn't get the mix of part A and part B quite right, temperature is less of an issue than the mix).
Moisture and temperature issues with the substrate tend to result in adherance problems, with the foam seperating after a while. That means air leaks, and other problems. It's best to stick with the manufacturer's recommendations as much as possible. Spray foam installation is a lot less forgiving than installing batts.
Bill
It will be easy to get the surfaces up to temperature in your situation. The farther the outdoor temperature is from 50° the riskier it is, and with spray foam there is always a risk of improper mix and cure. But I've had foam sprayed successfully with lower outdoor temperatures.