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Can you spray foam insulation directly on steam pipes?

If not, can I wrap them in thin fiberglass and spray foam over that?


  • Jamie Hall
    Jamie Hall Member Posts: 23,446
    Check the temperature rating of the foam. You may -- probably will -- be very close to its maximum, in which case it won't last well. Better to use an inch of fiberglass -- it comes in preformed, snap on sections...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Chris_L
    Chris_L Member Posts: 336
    I've used Great Stuff foam to seal around risers where they pass through the floor below the radiator valve without any problems. Also used it at the end of dry returns to seal the end of the old asbestos insulation to the pipes. It's been there probably 2-3 years without any signs of deterioration. (I think it is the window and door variety, but I am not sure.)

    If you read the safety information for these foams, however, it says not to use them at temperatures above 240F or on radiators or furnaces.

    I wouldn't use this stuff as the main source of pipe insulation, but for small areas it seems ok. And as Jamies says, check the specs for the foam you plan to use before you apply it.