We made a mistake analyzing the leak in one section of our roof. We paid professionals to fix the a valley and reflash the chimney next to it. Unfortunately, we did not realize that part of the problem was a low sloped roof with a sag next to the repaired section.

The sag/low slope section next to the repaired area runs 11.5' up to the ridge. The 17' length of the ridge sags 4 to 5" while the slope is 2.5 to 3" per foot. When roofers came out they said that in spite of the sag that the decking was sound.

At this point I want to try to fix this section of the roof myself. I wanted to to remove the shingles in this area, put down ice and water shield over the whole 11.5'x17' section and re-shingle to tie in with the 3-tab shingles on the rest of the roof.

Is that a bad idea or would the modifed bitumen roll roofing be a better way to go? I have been reluctant to consider the modified bit because I am not sure how to make the transition from the modified bit to the 3 tab shingles.

If both ideas are bad feel free to stop me before I do any more damage. Thanks.

 

Mark:

In most parts of the country, Ice & Frost is required for 3' up the roof, beginning at the edge of the roof. If you have a sag in your roof, and a leak, I would probably not just repair a section of it, and try to tie into the other shingles. Even a pro would hesitate to do this. You just creat areas for more possible leaks. I would probably strip that whole section of the roof, and even put ice and frost on the whole area then reshingle. Ice and frost will keep roofs from leaking. I can't see your roof, but I have the feeling that this may be a pro job. But maybe I am wrong. Have a good day.