I'm installing a vapour barrier over the dirt floor in my crawlspace. There is a water heater already installed and I'm wondering if it's a good idea to tape the vapour barrier directly to the bottom of the water tank instead of eptying it, disconnecting it, sliding the plastic sheet underneath and putting everything back together. My only real concern is that the moisture under the vapour barrier will cause the base of the tank to rust.


1 Answer 1


I wouldn't. You'd essentially be sealing the heater's fate of rust and decay. (See what I did there?)

First, you might find it less painful than you think to get the poly under the heater. A little levering or winching and it'll be off the ground the half inch you need. I'd put your main poly sheet down, then some thin plywood or something to protect it.

You might even take this opportunity to do the annual drain and flush you surely do, making the unit lighter while you lift it.

Otherwise, just cut around the heater. The moisture that gets through that small area probably won't be a big deal.

  • Thanks for the advice! I think I will take this opportunity to drain and flush the tank while I'm at it.
    – Gerry
    Commented Nov 6, 2018 at 21:24
  • I would think taping around the bottom would really accelerate the rustout. Several years ago I replaced a small 10 or 15 gallon unit that was under a house and it was totally rusted out on all the external metal I was not sure how it had not failed long before.
    – Ed Beal
    Commented Nov 6, 2018 at 21:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.