I have a leak around a vent pipe in my attic. Unfortunately I cannot get someone out to fix it for several days, and we have a hurricane coming so I can only imagine the rain is going to get worse.

I want to try to prevent as much further damage as I can to my ceiling, so I planned on either tying a towel around the pipe to catch water, or putting a pan/bucket under where the water is coming in.

Additionally however, I was advised that using a spray foam sprayed into the area of the roof where water is coming in could be a good temporary solution. I'm confused as to which to use however.

Here is a link describing the different foam types, one sounds water tight, one isn't. I'm worried that using a closed cell (water tight) foam could pool the water elsewhere and cause damage to another portion of the roof. Whereas the "open cell" foam is listed as not being water tight - would this foam even help me at all?

Keep in mind this is only meant as a temporary solution to hopefully get me through the weekend without significantly more damage. Which foam should I use? Are there any other pieces of advice I could do to limit damage?

My roof is on a 4th story townhouse, so unfortunately tarping my roof is not an option.

  • Are you able to work on top of the roof, or only from underneath?
    – Ecnerwal
    Sep 30, 2015 at 19:35
  • Only underneath the roof from attic access. I don't have a latter anywhere even close to tall enough to get on our 4th story roof.
    – Kritner
    Sep 30, 2015 at 20:09
  • If the neoprene of the vent flashing is the only thing deteriorated, filling up the gap with foam will not cause pooling any place It should not take a lot of closed cell foam to remedy the problem for the short term. It is better to only use what it takes to stop the leak, the flashing needs to move around the pipe for snow loads, if you have that. The foam will need to be removed to repair the vent flashing. All it takes is a replacement neoprene top that covers the original. nationalbuildersupply.com/…
    – Jack
    Oct 1, 2015 at 2:33

1 Answer 1


Application of foam from the interior will not stop water from penetrating the compromised flashing seal. The water that does penetrate may very likely end up someplace you would rather not have it. That being said, it will probably be better than doing nothing, judging by your description of the leak and considering the weather that is headed your way. The retro-fit seal linked in the comment from @Jack should help once you can obtain roof access, and you do not need to remove the foam to utilize it.

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.