I'm about to start finishing a basement half bathroom. I have a toilet that sits on an unfinished exterior wall. Should I have the wall drylocked, studs placed, board stock insulation installed, and green drywall put up in order to finish that wall? The toilet's water line causes me some concern about potential condensation that could form within the finished wall. Thanks, any input is much welcomed!

  • Do you have room behind the toilet to add greenboard / studs or during strips?
    – Ed Beal
    Jun 20, 2018 at 13:36
  • 1
    VTC. Questions remain unaddressed and OP hasn't been back.
    – isherwood
    Jun 20, 2018 at 14:42
  • I agree with vtc with so many questions asked that the op never voted or answered comments the close should be automatic unless a really good answer that is upvoted by peers.
    – Ed Beal
    Jan 8, 2019 at 5:38

2 Answers 2


You can slow down condensation on cold water pipes by insulating them.

What? Insulate cold pipes???

Sure, why not. The insulation doesn't care. The insulation will act as a vapor barrier to keep humid air away from the pipe, and will greatly slow the warm-up of the pipe. Remember, in condensing conditions, what is warming the pipe is the enthalpy of vaporization as water vapor condenses. The water vapor gives up 2257 joules/gram or 970 BTU/lb. when it transitions from vapor to liquid, and this is what warms the pipe until it equalizes to ambient. The insulation greatly slows this process, reducing condensation greatly.


The wall is concrete or this is wood framed? Is the exterior wall below grade?

It impacts the answer. but Exterior walls should be insulated. If it is concrete *(which if below grade it better be), then you could just concrete paint it.

If your goal is to have an attractive wall made of drywall, then you should stud it. pressure treated. Before doing this, does the wall have visible leaks? cracks? You can and would want to drylock it if so. And you might prefer then to panel it so that you can have an access door to the areas that concern you.

Follow local code, plastic, etc. As it is a bathroom, and in a basement, certainly get green board if you go the drywall route.

As for moisture, this is a bathroom, if there is a shower/sink, and even just a toilet, go for a vent. It will help you keep this area dry when needed.

As for the toilet itself, once the wall is properly insulated, and the space maintained at a consistent temperature, the only time there would be a real question of moisture on the pipe is if there is a lot of water flow, consistently. This could introduce sweating, but it shouldn't. If the toilet is properly plumbed, and the tank fill shuts off after use, this should never present an issue.

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