The situation: I have an old low-pitch tar and gravel roof. The corner of it (about 60 sq ft) I replaced the rafters and roof deck and placed some roll roofing on top. I used standard roof cement to adhere the roll roofing. I actually overlapped the roll roofing on top of the tar and gravel. This is the point where I have leaks - I have tried to add roof cement and glass mesh tape to the seam to reinforce it.

This is not working for me. I think maybe a rubberized product or something may work, but I need to know specifically what to buy and where I can get it. The product needs to be able to adhere to the tar, roll roofing, and old tar and gravel and create a waterproof coating over the seam.

Ideas? Thanks so much for your help. By the way, I know this is not the best way to do this!

 

If you value your household possessions, you'll hire a professional roofer. That said:

The roll roofing itself will leak even if you get that juncture sealed somehow. It is made to shed water, not repel it.

You need to take the whole roof off and put a 3 ply SBS self adhered roof on. 2 layers of smooth and a 'cap' sheet. Ultra19 will be the sealant of choice most likely, for detail work. Your nearest Roofing, not Lowes or Home Depot, supplier should have what you need.

That siad, I believe it's NOT a project for the DIY'er. Flat roofs have many pitfalls. More than I can ever cover here in 20-30 posts. Each system has a manual for it's application.

 

It will never seal if the gravel isn't spudded off first. Then if the gravel is removed and a nice seal is created it will last 6 months. A proper perm repair would be done with a real roofer and a kettle.