Insulating A Bathroom Wall/Pipe Freezing

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Jul 17, 2018
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Hi All:

We've been at this house for a 3 years. Every year when it gets 5 above zero or below, our master bath faucet freezes. We've had to let it drip every year and it runs up my water bill. The line running to this is on an outside wall. We live in a one story built on a slab.

We took off the bezel that surrounds the lever to select hot/cold for the bath and you can feel cold air behind there (in the winter months of course).

I've talked to three contractors and they all say the same thing:

This area of the house has been poorly insulated. What needs to happen is removing the siding from the outside, remove the foam board insulation, and insulate the pipes.

The two sinks in this bathroom do not have this problem. Their water supply lines go directly into the floor. We can't really tell but we think the shower supply lines are farther back, farther towards the edge of the slab.

One (retired) contractor suggested pink batting type insulation. The other two said closed cell foam is the way to go. [I'm not going with him, I hear foam is a lot better than batting]

Of the remaining two contractors , one wants to fill it with foam, further box it in with OSB. Insulate the area as much as possible. Reinstall the blue foam that surrounds the house and reinstall siding.

The other contractor said basically the same thing, only he says he'd like to also put a layer of house wrap over it, and maybe even put insulating blocks around the slab edge. He said they make insulation just for this purpose.

I was writing to see if this all seemed legit.

And, has anyone heard of a copper pipe freezing inside a slab in the winter? The coldest it gets here is 15 below.

Would the house wrap make any difference? What about the insulation next to the slab?

I am not a guy who knows about this stuff, and I appreciate anyone's knowledge they can share.
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