Chapter 1: The felt under the tiles of our post-war Woodley house looks black and brittle. Is the roof finished?
What we find
Underlay is the sheet laid over the rafters, beneath the battens, to catch anything that gets past the tiles. On houses built in the years of Woodley's post-war growth, that sheet is bitumen-based felt, and seventy years of loft heat and condensation have turned it dry and brittle. It cracks where it was nailed, and tears at the eaves and around the chimney, where it meets the walls.
From the loft you will see it plainly: black, flaking felt hanging between the rafters, light showing at the ridge, or nail heads with rusty streaks around them. Staining on the upper floor ceilings is often traced to the felt, not to the tiles. The concrete or clay tiles above it have often outlasted the layer meant to back them up, which is why a tile-by-tile patch rarely holds.
What we fix
Tiles in good order do not have to be thrown away because the felt has failed. We strip the roof in sections, tile by tile, stack the sound ones, fit a new breathable membrane (a vapour-open sheet that lets the loft dry out), renew the battens and relay the tiles. Broken or soft ones are replaced with matched tiles. The roof lasts for years after that, at much less than the cost of an entirely new covering.
That is a full re-cover, though, and a job on that scale is notifiable, so the building control application is something we take care of. A concrete-tile re-cover on a three-bedroom semi is reported at £6,500 to £10,500, though the real figure depends on tile choice and access at your Woodley address. If the roof is sound apart from one slope, we say so. Your fixed quote follows the survey. Details of the process are on the roof replacement page.