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Air Sealing Steam Pipe Penetrations Through Floor

<i>"You can Do It. They Can Help" :)</i>


  • Peter Means
    Peter Means Member Posts: 27
    Air Sealing Steam Pipe Floor Penetrations

    After an energy audit revealed the need to seal holes in my basement ceiling, I'm trying to air seal the steam pipes holes that run up from the basement. Some of the holes are about 1/2 inch larger than the pipes on all sides, while some have up to 2 inch gaps around them, where someone did a bad job hacking through the rim joists.

    The previous owner used Great Stuff, which has now melted, or burnt. I'm looking for the best way to seal these larger gaps. Do I back them with pink fiberglass insulation, or something else, then use hi-temp caulk to air seal?

    I've seen the "fireblocker" great stuff, but that doesn't seem quite right... or is it okay?

    That job is really prep for my project of insulating the sill boxes with 2" thick, foil faced, rigid insulation (Tuff-R), that I will Great Stuff around. So I guess a second question is how close can I get to the steam pipes with the Tuff-R insulation? Will it melt if too close? I'm planning on cutting rectangles to fit the sill boxes with cut outs for the pipes, but how close can I get?

    Actually, to be more accurate, some of the penetrations go straight up and don't go into the sill, while a few do.

    Confused homeowner, so go easy on me. Thanks very much in advance!--Peter
  • Brad White_201
    Brad White_201 Member Posts: 52

    at least 1/2" molded fiberglass pipe insulation to fill the annulus (the circumferential space) as much as possible.

    Seal the rest with 3M Firestop or other UL Listed RTV silicone sealant. Cover with an escutcheon plate and you are done!
  • The word for the day,,,

    is annulus, just be careful how you use it in a sentence! ;)
  • kpc_36
    kpc_36 Member Posts: 21

    how did you make out w/ the hot water & the 006? kpc
  • Brad White_200
    Brad White_200 Member Posts: 148

    whomever uses that word, may well be one. :)
  • Peter Means_2
    Peter Means_2 Member Posts: 9

    Hey Kevin! Thanks for asking.

    We lived with the issue a few more weeks. Warm then hot dom. hot water. Then the wife's father was visiting from VA. He used to be a maintenance guy in a paper factory, and so was able to help me out. He replaced the pump, added a valve just after, to bleed air. He concluded that even though the pump was moving, it was barely moving and thus shot. He believed an air bubble got into the system and "when the pump gets air is can fry it" or something like that. He also moved a check valve (I think) from the right side of the pump to the left side and up on a horizontal section above the water heater.

    Seems to be all working so far. He's told me if it happens again, bleed the air bubble.

    Thanks for following up. Hope you are well.--Peter
  • Peter Means_2
    Peter Means_2 Member Posts: 9

    I'm going to ask at HD, what they might have to seal my annulus! LOL. Thanks Brad for the good info.

  • Peter Means_2
    Peter Means_2 Member Posts: 9
    Excellent Point!

  • For some reason,

    I am reminded of this can of food a friend of mine had once, labled "Fish ***holes in a Light Tomato Tauce" we opened the can and it was Spaghetti-Os. ;)
This discussion has been closed.