Is EPDM better than roofing felt?

Simple, open roofs where a single sheet can cover the area with minimal jointing. Fewer seams means fewer of the places where flat roofs usually fail, and the material remains flexible over a wide temperature range.

Detailing is done with formed corners and adhesives, which needs care around complex kerbs and penetrations.

Roofs with lots of detail: upstands, kerbs, penetrations, awkward shapes. Torch-applied and self-adhesive systems dress into details reliably, and a local repair can be bonded in compatibly without disturbing the rest of the roof.

Modern reinforced systems are a different product from the thin felt roofs people remember failing, and should not be judged by them.

Fall, drainage, upstand heights, deck preparation and workmanship. A well-installed felt roof outlives a poorly installed EPDM one, and the reverse is equally true.

Ask why a system has been chosen for your roof specifically, rather than accepting a general claim about materials.

A manufacturer's guarantee typically covers the material itself when installed by an accredited installer to the manufacturer's specification, which is a narrower promise than it first sounds. It says little about workmanship on its own, and a poorly formed upstand or badly lapped detail can fail well within the guarantee period without the material being at fault, regardless of how the material itself performs over its rated lifespan.

Ask separately what the installer's own workmanship guarantee covers and for how long, and whether the installer's accreditation with the manufacturer is current, since accreditation can lapse without the marketing being updated. A guarantee document that names the specific product batch and installation date is worth more than a general certificate handed over after the job, and it is worth asking whether the guarantee is insurance-backed in case the installer later stops trading, which protects you regardless of what happens to the company that carried out the work.