Flat & low-slope roofing

Shingles need slope to shed water, and porches, dormers, and additions often don't have enough of it. Those sections get a membrane instead: EPDM rubber fully adhered to the deck, with the seams, edges, and terminations detailed so standing water has nowhere to work its way in.

The usual signs it's time are ponding that lingers for days after rain, seams lifting at the edges, or patches layered on patches. A membrane roof that's detailed correctly is quiet, tight, and easy to check once a year.