Flat Roof Replacement in Windsor & Berkshire

Most flat roof failures we see were not caused by the covering. They were caused by laying a new covering over a deck that was already soft, rotten or sagging. The boards move, the new surface splits and the leak is back within a couple of winters.

So we check the deck first, every time. Where it has failed, we strip it back and lay new plywood decking with the falls set correctly so water runs to the outlet instead of ponding. Only then does the new covering go down.

We build and repair flat roofs on:

• Garages, the classic failing felt roof on homes across Berkshire and South West London
• Extensions, including junctions and upstands where the flat roof meets the house wall
• Dormers, small roofs with a big job to do, detailed to work with the pitched roof around them

Much of our flat roof work is in South West London, and our recent flat roofs in Kingston upon Thames are photographed stage by stage in our case studies.

Patching felt over felt works when the problem really is on the surface: a split, a blister or a failed joint on a deck that is still dry and solid underneath. When that is what we find, that is what we tell you, because a repair is cheaper for you and it will hold.

It stops working the moment water has got past the covering. Once the deck below is saturated, bonding a new layer on top seals the moisture in rather than letting it out, the boards carry on rotting where you cannot see them, and the patch lifts or splits within a couple of winters. If the joists themselves have gone, no covering will hold at all, because the thing it is fixed to is moving.

That is exactly what we found in Chatham. From the ground the roof just looked tired. Once the old covering came off, the deck was saturated and several joists had rotted through, so another patch would have failed and the money would have gone with it. A full flat roof replacement was the only honest recommendation to make.

Signs a repair is unlikely to hold:

• The roof feels soft or springy underfoot, which means the deck has taken on water
• Water is coming back in after previous patches, often somewhere different each time
• Ponding that never dries, a sign the deck has sagged or the falls were built wrong
• Staining, damp or sagging on the ceiling below, not just at the edges
• The covering has failed in several places at once rather than one

We inspect before we quote, photograph what we find and put the recommendation in writing. What a new flat roof costs depends on the size of the roof, how much deck and timber has to be replaced, the access and the system you choose, which is why the figure comes after the inspection rather than over the phone.