In our upstairs bathroom, the toilet and cold faucet in the sink stop working every winter when it is cold.

The shower works and the hot water at the sink faucet work.

We have tried heating up the room to 85. Looking for the source line and trying to heat it but can't. Our master bath is on the other side of the shower and we do not have any problems. Our daughter's closet is on the back side of the toilet and sink and her room is usually warm.

We tried turning on the hot water and holding it with rag and forcing water back up the faucet for an airlock and it didn't help either.

There is only one wall to the outside and it has a window.

We don't think there are outside lines but we think the cold line goes up into the attic. We hired someone to look and they said it was insulated where they could see but it might not be when it goes into the wall.

Nothing ever leaks so pipes never break. When the weather warms up, it works again. Drawing enter image description here

Master Bath

  • 3
    Yeah, you need to "follow that pipe". It is freezing; it's just not freezing enough to crack it. So far. Jan 20, 2020 at 1:08
  • 2
    I'm with @Harper-ReinstateMonica on this. Clearly the line is freezing. It's either not freezing enough to split the line or the line is flexible enough to survive freezing. Either way, you need to track it down and fix the problem.
    – jwh20
    Jan 20, 2020 at 1:19
  • You don't really have a question in your question. What are you asking? If this is OK to leave, or how to fix it? Jan 20, 2020 at 2:20
  • I'm looking for advice on first what the problem might be and then how to fix it. Appreciate the responses already. Thank you!
    – SaminIowa
    Jan 20, 2020 at 2:30
  • If you could provide a sketch of the baths layout and the walls it could be helpful, I am guessing the feed is on an inside wall to the other bath first. If it goes into the ceiling insulation may not stop it from freezing but may be the reason it has not broken. I have had lines in the ceiling freeze and break. If the supply from the master is in the ceiling I would want to add some self regulating heat tape. It is more expensive but the stuff I use is for inside attics and crawl spaces (not all heat tape is approved for use in these locations).
    – Ed Beal
    Jan 20, 2020 at 15:52

2 Answers 2


As others state, fix it before the pipe bursts, and you have expensive water damage, possibly making the house unlivable.

Temporarily, you might try putting insulation over the outside of the wall where the pipe runs. You could try following the path of the pipe with a stud finder, though if it's plastic pipe, it might not show. Then make place bats of insulation outside long that path, and cover them with a wood frame to prevent that insulation getting damaged.

  • I added images to the original post of the bathroom, the master bath next to it and a drawing. The master sink and toilet face the outside wall where the bathroom that is freezing faces an interior wall. Thank you for all the help.
    – SaminIowa
    Jan 28, 2020 at 2:41

From your description, it sounds like maybe the line up in the attic is just insulated by that foam pipe insulation. If it get cold enough out, that will not be enough to keep it from freezing. It might be worthwhile asking who you hired to check it out about that If they could see the pipe, it was not insulated enough, even if it was insulated by that pipe insulation. In that case, I would recommend adding insulation around the pipe (you could do lose fill blow in, or lay bats around and over it, depending on what is easiest in your attic).

From your description, it doesn't sound like the pipe actually runs through the outside wall, so I would focus the attention to the attic.

  • Thank you, I added images to the original post for review.
    – SaminIowa
    Jan 28, 2020 at 2:42
  • Any other suggestions after seeing the drawings?
    – SaminIowa
    Jan 31, 2020 at 2:50
  • Well the drawing makes it pretty clear that most likely the pipe is either in the wall or in the floor along the outside wall, going from master to second bathroom. What's underneath the room? At the toilet in the second bath and master bath, where does the water valve stem out of - wall or floor? Jan 31, 2020 at 14:19
  • Another bathroom is directly below that bathroom. Our family room is directly below our master bath room. Value stems from the wall.
    – SaminIowa
    Feb 8, 2020 at 15:09
  • Well I think it sounds very likely the pipe is running in the wall between the shower and toilet, or maybe in the floor there close to the outside wall. You will need to figure out how to locate that pipe, see if you can rent an inspection camera locally, or maybe even a locator tool if your pipes are metal, it might work to use that. The long term solution is to open up the wall and insulate, or re-route the pipe. Short term, you can leave the facuet in your guest bath on a slow trickle when it gets cold to keep water flowing and hopefully keep it from freezing. Feb 17, 2020 at 18:54

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