Rubber Membrane Installed Correctly?

We were looking help water run-off in a valley where multiple roof lines meet.

The roofers just finished the job yesterday, but it seems like it should be smooth.

Here was the information on the bid for this project.

  1. Remove shingles from flat roof between the garage and house

  2. install a 1/2" fiberboard over the flat roof deck

  3. Install a rubber membrane fully adhered to the fiberboard

  4. Re-shingle the area surrounding the flat roof with OC black shingles

Thanks in advance for any advice.

No. Not adhered and a part of it covered with mastic, which is bad on an EPDM roof.


Thanks donl. I’ll be meeting with the project consultant this week. Is the only option to redo the whole thing?

Correct, needs to be redone by someone experienced in epdm.

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Yes. Remove and replace, fully adhere.


Its loose laid and needs to be adhered with aleast 1/2" HD board over the decking

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Thank you for the responses.

The Project Consultant came out yesterday and he agreed the membrane needs to be re-installed with a water-based glue. I will also check to make sure there is a board over the decking. I’ll post a photo here after the new membrane is installed.

The epdm needs to be replaced and installed properly. For that small of an area there is no reson to reinstall the same rubber, who knows what the original installers did to it under the shingles.


Epdm can be installed, fully adhered to clean OSB. This is 045. Water based adhesive. This should be a very simple repair.

Good roofing practice, never fully adhere anything directly to the deck.


Are you not supposed to torch directly to plywood either?

Vaa primes it first.

The project consultant agreed a new rubber membrane needed to be installed. He was the lead on re-doing the project and he spent a few hours with the foreman adhering the new membrane. The piece seems to go up further now under the shingles, and he added a metal piece at the end to help extend the run-off onto the lower roof. Thanks for the help and advice!