Roofing

The cause:

This flat roof had failed ultimately due to the neighbor’s plant climbing over the parapet wall and gradually pulling out the pointing where the felt goes in to the chase which then allows water to get under the felt allowing the water to slowly seep on to the supporting timber work, and as most ceilings are plaster boarded it can often be beyond a simple repair by the time you notice.

This particular roof was so bad that the joists and wall plate had completely perished and the only reason it did not collapse was due to a separate steel holding up the joist.

The remedy:

We completely stripped off the existing felt, timber deck, joists and wall plate and removed 3 layers of tiles from the base of the pitch roofs, we then re built one end of the parapet wall, replaced the wall plate and joists and put new furings on the joists measuring 4 inches at the back and tapering down to 2 inches at the front creating a fall so the water runs off of the roof, we then put a new timber deck on top using 18mm structural ply, this is then primed ready for the 3mm thick high performance underlay which is fixed with a blow torch, melting the bitumen on the underside of it giving a solid fix to the timber deck a few inches up the parapet wall. We then put 3mm thick mineral felt on top, this again goes on the timber deck over the undercoat and about 5 inches up the lay boards (the boards that run about 6 inches up each pitch roof), we then put smaller pieces of mineral on top of the top sheet, these run a few inches from the flat up the parapet wall and in to the chase and then a bead of lead mastic is put in to it for a final seal, the tiles where then replaced making a completely water tight roof which will last for years.