We recently did remodeling and replaced copper piping with PEX. The kitchen and master bath are both on an exterior wall. We are in cold climate and we have had 2 days of extreme cold (-10 to 3 degrees currently). When piping was replaced the walls were also insulated they weren’t previously. Both kitchen sink, water to refrigerator and master bath sink have no water flow. House is very warm, drywall underneath both are very warm yet obviously the PEX has frozen. Very baffled as I understood PeX takes longer to freeze than copper. My neighbor across street with no insulation, exterior wall sink, very cold under cabinet yet still has running water. Very confused! Any thoughts on how to defrost? We have 3 more days of this extreme weather and then gets into the 30’s.

  • FYI. The neighbor has copper piping.
    – Geri
    Dec 24, 2022 at 15:32
  • most likely there is an elbow that is brass or hard plastic that has frozen . The inside diameter is much smaller in the elbows and "t" fittings leaving less water, so more likely to freeze. Unless you can get to it not much you can do.
    – RMDman
    Dec 24, 2022 at 15:42
  • Cold climate - no insulation! Wow! Hopefully the insulation you had put in was done properly with the insulation between the pipes and the weather. You need to narrow the search area for the freeze point. Is the problem on both hot and cold? Does the toilet in the master bath have water? If the kitchen and master bath are on the same exterior wall the freeze may be between the main shutoff and the first room after the main. If you can narrow it down you might be able to remove a few vent holes in the drywall and get a hair dryer to get some heat on the problem. I've done it before.
    – HoneyDo
    Dec 24, 2022 at 20:37
  • I'm not sure I would expect pex to be slower to freeze. I would hope it would withstand damage from freezing longer...
    – keshlam
    Dec 25, 2022 at 5:06

1 Answer 1


Depending on where the pipes are in the wall assembly, the insulation will also prevent the heat from reaching the pipes. When you have cold weather keep these taps dripping to prevent a future freeze or move the pipes to non-exterior walls.

Keep the cabinet doors under the sink open and heat the room as much as possible to allow the heat to move to the frozen area. Getting a ceramic heater that you could point at the exterior walls you suspect have the leak could help. Keep the taps slightly open so the water can move when it expands.

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