During the winter chill here in DC, one of my pex pipes that is not insulated and basically exposed to the elements cracked. I blame the contractors who didn't insulate and finish the job, literally leaving a hole in the drywall where you could see and touch the pipes... outside.

I'm back in town and want to repair the cold water pipe and insulate it, but I am a newbie and I don't know how to do this. Do I just put normal wall insulation (fiberglass) in there? I heard something about a heat coil that automatically turns on when it gets colder?

I have googled a bit and found "Heat Cable for Pipe Freeze Protection" on Amazon which looks both super affordable and simple, but I'm not a plumber and I don't know if this is the recommended option. Any advice would be great!

1 Answer 1


The "heat tape" you are referring to is what we use in Western Maryland as the "go to" way to keep our PEX piping from freezing. It works great and is a low cost way of making sure your pipes don't freeze. Warning though, make sure you have a way of always knowing the tape is working. If you bury it behind a wall totally and can't check it a few times during the cold season, you run the chance of it malfunctioning. You also have to make sure it does not overheat by overlapping the wire on itself. And if the power goes out and it's below freezing, it also won't help at all. Our company has rentals that are very old homes and apartments and the piping in some of them are very close to the exterior surfaces of the units so we use this all of the time with great success. When we are using heat tape for plumbing behind walls and under floors, we use a product called Hotline internal pipe heaters. This goes inside the pipe rather than outside. It also prevents overheating that can cause a fire. As I said before, if you bury regular heat tape behind something you have a huge risk for malfunctioning which can be anything from a non working tape to a fire. Also, if you can get another type of insulation around the pipe, such as spray foam, that should do the trick.

  • I don't believe heat tape is listed for use inside a wall or I have not seen any that is. From what I have seen pex usually holds up well to freezing. I would want to put insulation on the outside of the pex but leave the inside open so the warmth of the inside wall could help keep it from freezing.
    – Ed Beal
    Feb 19, 2019 at 1:08

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