I'm doing a little project where I'm fishing some CAT6 cables from a 3rd floor bedroom to a second floor office. Because of the layout, I had to first fish the wire along an outside-facing wall before fishing it down inside the second floor wall separating the office and the second bedroom.

In order to do this I've had to cut some small holes in my drywall in order to position my flex drill bit and drill through the studs. Since this is an outside facing wall, there are patches of pink insulation between each stud, and there is also a sheet of plastic covering the insulation and the studs (based on my research, this would be a vapor barrier, or a moisture barrier, I think? I still can't tell the difference between the two).

My question is this : as I was cutting the holes in the drywall, I also cut through the plastic covering the insulation. When I'm done fishing all my wires and it's time to patch everything up, is it important to replace the plastic that was originally covering the insulation? And if the answer is yes, what's the best way to do this? The holes I cut out are approximately 4" x 6"

The best answer I could find was that in a basement, it's necessary to have to have a vapor / moisture barrier to conform to building code. But I couldn't find any information about bedrooms.

I live in Calgary (Alberta) if that matters.

1 Answer 1


You are fine. Vapor barrier holes of that size and bigger are typical in wall construction, in the form of switches, outlets, plumbing, etc.

Let's keep calling it a vapor barrier. Makes geeky engineers squirm in their ergonomic wheeled chairs....

  • There should not be any substantial holes in the vapor barrier. That's the whole point: keeping the water vapor out of the insulation, where it will eventually find the dew point and condense to liquid, creating a host of potential problems. Patch whatever you can and try to properly seal others you find.
    – Upnorth
    Commented Aug 23, 2017 at 21:35
  • I call bologna on that comment. Innerweb dribble, not based in reality.
    – NPM
    Commented Aug 23, 2017 at 21:40

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.