How long does a felt flat roof last?
Traditional and modern felt systems vary, but flat roofing generally has a shorter expected lifespan than high-quality slate or tile roofing. Installation quality, drainage, sunlight, detailing and maintenance all influence how long the covering remains watertight.
What shortens a felt roof's life
Felt roofs are affected by sunlight, temperature movement, standing water and how well the details were formed. Upstands, drips and outlets are where failure usually begins rather than in the open field of the roof.
Older single-layer work and roofs with poor falls tend to reach the end of their life sooner than well-detailed multi-layer systems.
Signs of a felt roof nearing the end
Blistering, splits, brittle or crazed surfacing, seams lifting and persistent ponding all suggest the covering is deteriorating rather than suffering a single defect.
Where deterioration is widespread, patching tends to buy a short period before the next failure elsewhere, and replacement becomes the more economical route.