At what temperature should blown foam insulation be installed on a steel roof with 2×6 trusses?
I have a 24×60 pole barn and want to keep moisture from dripping on inside items. It`s getting cold and I want to know at what temperature should blown foam insulation be installed? I`am more concerned with moisture than R value but plan on having 4 inches blown on the roof.
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Gordon,
You have to check the spray foam manufacturer's specs to determine the minimum temperature of the substrate for spray foam application. Some manufacturers specify that the substrate must be between 60°F and 80°F; others specify 40°F to 90°F.
The best person to ask about these issues is your spray foam contractor. For more information on these issues, see Spray Foam in Cold Climates.
One other point: In general, you don't want to install spray foam directly to the underside of steel roofing. Spray foam insulation is like glue, and if the stuff is adhered to steel roofing, it will make future roof repairs or roof replacement much more complicated.
If you can install a ceiling in your pole barn and find a way to insulate your ceiling, you'll have a better solution. Or perhaps you can find a way to drape a membrane that will collect the condensation and drain it away, thereby protecting your storage items.