Installing self adhered roofing over felt

I have some CertainTeed self adhered roofing to install on a low slope roof. The roof already has 30# felt on it.

The system uses a self adhered membrane layer, then a self adhered asphalt cap sheet layer.

Do I put the self adhered membrane layer over the felt, or do I need to remove the felt? If I go over the felt, the only thing really holding everything down (since there are no nails involved in the CertainTeed system) is the staples on the felt.


I would tear it off and apply to fresh deck. Primed.

Link is for another thread on the same self adhered products.


thanks, that’s a great thread!

Looks like I should tear felt off. Do I use CertainTeed primer, or can I get whatever?

Running the base sheet UNDERNEATH the drip edge at the bottom is new to me. I used to do a lot of T-lock roofs and we always ran the felt over the drip edge, but I realize it’s not exactly the same thing.

For residential systems Certainteed leans more towards using their nailbase and self adhered cap. If you went this route you wouldn’t have to remove the felt. … Manual.pdf

personally I’d use the commercial system and install the midply as well just so you have two layers of modbit without nails through it. … ochure.pdf

Any asphalt primer will work should you use the SA base sheet.

As someone else said, if you use the MA base sheet you can go directly over the felt. Although the best way would be to
tear the felt and put down high temp ice and water barrier. We tend to use the MA base sheet for peel and stick applications
because it makes it easier to replace to roof down the road. If you prime your wood deck and adhere the base sheet directly
to wood then the next guy is going to be replacing the plywood along with the roof. I do think that a slightly higher warranty
is given when using the SA base however; should you care about such things.