Hello, Due to ice dams from this winter, I had water leaking in my garage from the attic above, and ultimately from the roof. I have used roof tar to patch the leaky spot outside, now I'm trying to determine my next steps. I have some pictures of the wood where the leak was coming into the house. Looks like some mold/mildew. The drywall is damaged inside the garage. How should I begin repairing the wood/plywood in the attic? Should I run a dehumidifier in the attic? This is part of the roof and ceiling to the garage. Thanks.
Jul 05, 2014, 02:19 AM
The drywall is damaged beyond repair - you need to cut out the bad areas and replace with new.
The OSB roof decking is also damaged and should be replaced. I can understand you not wanting to have to tear the shingles off in that area (although this would be best)so at the very least you need to shore up under the soft spot on the OSB with some solid blocking. However, since the OSB has already degraded, this is a short term fix.
As is the fix using roofing tar. It may last one season, probably not. It will leak again.
To get it fixed for good, you nee to remove the damaged section of OSB (and the shingles above it). Your ice dam repair should be a solid, unbroken sheet of roofing material that comes up off the edge about 3' or so. This really should be done all around the house. Easier to justify if you are due for new shingles.
Jul 06, 2014, 10:16 AM
Thanks for the prompt response. Just so I understand, your stating the correct fix would be to:
-remove the shingles on/around the damaged OSB, -remove/replace the OSB that has begun to degrade, -add a 3' section of roof flashing, and -replace any damaged drywall on the interior
Is that accurate?
Jul 06, 2014, 10:49 AM
That is correct. The only thing to clarify is that the entire roof edge should be protected by an ice dam. While you currently have this damage in this one place (hopefully) it could happen anywhere else.
Jul 06, 2014, 01:45 PM
As Jaybee has suggested you should apply an Ice and Water Guard membrane along the whole edge of the roof where eaves exist. This membrane is 3' wide and sticks to the sheathing. This is then covered with tarpaper and then shingles and prevents ice and water damage because of ice dams in the winter. Ideally it is also layed in any valleys your roof may have. Using this prevents further periods you may have with ice-daming in winter. The time to apply it is of course when you plan to re-shinge your roof. Using it now repair this small area will prevent the problem in that one area of your roof but leaves other areas open for ice-daming.
Below is a link to a product that I'm referring to: