Roof leaks where new and old roof meet. How to fix?

Question

I built an addition to my garage two years ago and I have some serious leaks now. The old roof was 6/12 pitch and it goes into a 2/12 pitch. I assume that is where the water gets in. Then it will run down a rafter a ways before dripping down.

I tried tarring the roof where the pitch change occurs, but the leaks came back. So now I need to do something more drastic. I have been thinking that I should get a roll of 24" flashing and run it down the valley. I could slide it under the shingles above the transition point and tar/nail it down below the inflection point.

Would this work? If not, what do you suggest I do?

Good info so far. I think I may try a combination of what has been suggested.

I wish I had known about the Grace product. I would have put it down if I had known about it. It appears they make it in 18" strips. I think using 24" flashing with a couple of overlapped strips of the Grace water and Ice underlayment might solve my problem.

If not I'll scrap it all off and do it over again.

Answer 1

My suggestion is to tin the junction of the two roofs and put two rows of water and ice barrier down as added protection. A 2/12 pitch should actually get a rubber covering as shingles will not hold up long under those drain condition unless you have good sun exposure.

Answer 2

Been there, done that. Personally, I don't like seeing exposed flashing because if you break up ice jams on it-you can easily pierce it and start a new leak. What I've done is peeled back a couple courses above and below the joint-make sure the tarpaper/roll sheathing is intact or add some-then lay down the flashing about 2/3 above the joint, 1/3 below and use tar cement to hold it in place. (less nails, less leaks) then start new shingles from the bottom up-and carefully end up with your last new course underneath the original above. this way you have the flashing protected with double layers (overlap) of shingles. If there is any movement in that joint, less chance of the flashing pulling up off the shingles to expose holes-the shingles will keep it covered. I have a porch roof butting up to the dining room roof (1 story) and had that all reshingled several years ago and the contractor did NOT do it-and we get ice building up and leaking down under every year. Next summer other projects should be done and I'm going to personally do it right with the flashing.

Answer 3

Any roof under a 4/12 pitch should be covered with Grace water and Ice sheld before roofing with with shingles. Was this done?

Answer 4

sounds good to me,