We had the basement done (converted into rooms, drywall ceiling, etc). It seems that there are pipes near the side of the house that freeze up when the temperature gets < 10 degrees F. I opened up a small area of the drywall and can feel a big draft of cold air in the cavity. It seems that the section of pipe that freezes only services the toilet and washing machine located above it (1st Floor) - so they don't work now. (for some reason the sink in that bathroom still works - so leaving the sink drip probably won't help). I pup a space heater in that basement room - and it helps some when the temperatures are a little higher.

Any idea other than ripping open the entire length of ceiling in the basement?

  • 1
    Rip open the end near the wall, find the hole providing the cold draft, and plug it.
    – Ecnerwal
    Commented Jan 16, 2022 at 17:45
  • Running the water in the sink (not "dripping") might actually help, if the pipes split off from each other- it will bring warmer water to the junction point, and if the pipes are copper heat will conduct along the pipes. Of course, depending how the freezing has gone and the type of pipes, you might find the ceiling gets destroyed anyway if the pipes have cracked open.
    – Ecnerwal
    Commented Jan 16, 2022 at 17:58
  • Add heat tape near the exterior wall.
    – Lee Sam
    Commented Jan 16, 2022 at 18:45
  • It’s probably in a rim joist bay. Those are a PITA to insulate. Spray foam is your best bet. You can buy kits from big box stores with enough foam for one or two bays. Commented Jan 16, 2022 at 21:33

3 Answers 3


Don't be so hesitant to open the drywall, it's not hard to fix drywall. Paint is the hardest part - do you still have some?

Basically you need to insulate that cavity, but the details depend on what's back there, which you presumably don't know.

You may be able to thread an electrical pipe warmer from up above, following the pipes that come into that washroom above.

What kind of floor is it? Would it be easier to open the floor, instead of the sink?

If the sink works, but the washing machine doesn't you need to figure out what's going on back there - perhaps it's not freezing where you think it is - is the contractor who did it still available, maybe he remembers what he did?


Aerobarrier could probably seal the air leak. It isn't cheap though. They setup a latex misting machine and depressurize the house driving the latex mist through all cracks and sealing up air leaks - that could prevent future freezing.

What kind of siding do you have on the outside of the house? I've fixed frozen pipes by taking off the siding and replacing over gutting tiled shower walls.

  • 1
    I've never heard of a latex misting machine - are you sure that's a thing? It seems to me it would coat every single thing in the house with latex.
    – Ariel
    Commented Jan 16, 2022 at 19:01
  • aeroseal.com/aerobarrier Commented Jan 17, 2022 at 7:54
  • That's not used on a finished house, it's used during new construction. Although it might work here, if they can target just the leaking cavity, but if any leaked into living areas it would ruin items in the home.
    – Ariel
    Commented Jan 17, 2022 at 17:35

You're first going to have to find out where the cold air is entering the ceiling/wall cavity. It's not necessary, but would also be helpful to know where the pipe is freezing which is probably near where the air is entering.
You then need to get some insulation between the pipe and the frigid air.
Any professional home builder/plumber will avoid running water lines through or along an exterior wall in a cold climate area. If you're lucky the ceiling joists and the pipe run perpendicular to the exterior wall toward the interior which will make it easier to get insulation into the exterior wall end of the cavity between the joists. This will probably require cutting out a small section of drywall from the ceiling near the wall.
Once you have insulation in place you can supplement it with heat tape. Another option is to install an open vent in the ceiling between the joists to allow warm air from the finished basement to rise into the joist cavity.

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