The right felt system for its roofing role
Application made clear
We identify whether felt is the covering or a pitched-roof underlay.
Substrate checked first
We consider deck or supporting condition before installing new felt.
Edges sealed with care
We finish laps, outlets and upstands to control water properly.
Different jobs for felt on different roofs
Roofing felt can mean the outer waterproof covering on a flat roof or the secondary layer beneath slate and tiles on a pitched roof. The distinction matters because each application fails in a different way. On a flat roof, blistering, splits, open joints and damaged edges may expose the deck below. On a pitched roof, ageing or torn underlay can reduce protection beneath the outer covering. We inspect the relevant build-up, including signs of trapped moisture and substrate damage, before explaining whether a local repair is practical or the felt system needs wider renewal.
Preparation, laps and edges done properly
For flat roofing, a sound deck and clear drainage route give the felt system a proper base. We prepare the surface, form sealed laps and finish outlets, upstands and perimeters so water doesn't creep beneath an edge. On pitched roofs, felt or membrane sits below treated battens and the outer slate or tile covering. It acts as secondary protection rather than the first line of defence. We fit the suitable layer as part of the roof build-up and pay attention to penetrations and eaves, where poor detailing can direct water into the structure.
Frequently asked questions
Can blistered roofing felt be repaired locally?
A local repair may be suitable if the damage is limited and the deck beneath remains sound. Widespread blistering, repeated splitting or trapped moisture can support a case for renewal. We inspect the extent before recommending either route.
Is pitched-roof felt meant to stop every leak?
It provides secondary protection beneath the slate or tiles, but the outer covering should shed most rain. Damaged tiles, faulty edges or failed flashing still need attention. We assess both layers when investigating water ingress.
Why does the flat roof deck matter so much?
Felt needs a stable and suitable substrate. A soft, wet or uneven deck can undermine a new covering and affect drainage. We check its condition during preparation and explain if damaged areas need attention before the felt is installed.