Can EPDM Replace an Old Felt Roof Without Altering the Whole Roof Structure?

A common concern among Emersons Green homeowners considering a switch from an ageing felt roof to EPDM is whether the change means major structural work to the rest of the roof, or whether it can be done as a relatively contained project focused purely on the covering itself. In most cases, replacing felt with EPDM does not require altering the underlying roof structure, provided that structure is in sound condition to begin with.

EPDM is typically installed directly onto the existing roof deck once the old felt has been stripped away, using the same timber boarding that supported the felt in the first place, as long as that decking has not suffered water damage or deterioration. Because EPDM is applied as a bonded membrane rather than requiring a different structural build-up, the transition from felt to rubber is often a like-for-like replacement of the covering rather than a project that touches the joists, rafters or overall shape of the roof.

The important caveat is what is found once the old felt is removed. Felt roofs that have been leaking, even in a small and unnoticed way, can allow moisture into the timber decking beneath over time, and this sometimes leads to localised rot or softening of the boards. When this is discovered during the strip-out on an Emersons Green property, the affected sections of decking do need to be repaired or replaced before the new EPDM membrane goes down, but this is generally a targeted, straightforward carpentry repair rather than a full structural rebuild.

Falls and drainage are worth considering separately from structure. If the original felt roof had inadequate falls that caused standing water, a switch to EPDM presents a good opportunity to correct that with tapered insulation or firring pieces, improving drainage without needing to alter the roof's structural framing. This is an optional enhancement rather than a requirement, but it is often worth discussing at the same time as the covering replacement.

Upstands, edge trims and any flashing details around chimneys, walls or rooflights are generally reworked as part of the re-covering process regardless of the material chosen, since these details need to suit the new membrane. This is standard practice on any re-roofing project and does not represent structural alteration, simply the correct detailing to keep the new EPDM roof watertight.

From the household's point of view, this generally means a felt-to-EPDM switch on an Emersons Green property is a contained project measured in days rather than a disruptive undertaking involving structural engineers or building work beyond the roof itself, assuming no significant decking repairs are required. Even where some decking replacement is needed, it is typically confined to the specific damaged sections rather than the whole deck.

For the vast majority of Emersons Green properties with a felt roof reaching the end of its useful life, switching to EPDM is a covering replacement project rather than a structural one, assuming the deck beneath is confirmed to be sound once exposed. The main unknown before starting is always the condition of that decking, which is exactly why a proper inspection at the outset is so valuable.

If you are considering replacing an old felt roof with EPDM on your Emersons Green property, Brunel Roofing Bristol can inspect the existing structure, identify any decking repairs needed, and explain clearly what the project will involve before any work begins.

More EPDM Roofing Advice for Emersons Green