Some flat roofs are tired. This one in Chester had gone well past that. When the covering came off, the boards underneath had rotted to the point of breaking up, and in places there were holes straight through into the space below.
It sits on what looks like an older property, enclosed by white-painted walls on two sides, with a lower flat roof next to it. We cleared out the rotten material, laid a new deck and finished it in EPDM rubber roofing.
What we found
The first two photos are the ones that tell the story. The old boards had turned soft and crumbly, soaked through and falling apart, and sections had given way between the joists. Along the edges, water staining and debris showed that moisture had been getting in for some time.
This is the usual end point of a flat roof that has been leaking slowly for a long time. Water gets under a split or a failed edge, the deck soaks it up, and because the covering above still looks more or less intact nobody sees the damage until it is serious.
Clearing out and re-boarding
All the rotten decking was taken out, leaving the joists open. One photo shows this halfway through, with the new OSB already laid over part of the roof and the bare joists still showing beyond it. The finished deck then ran wall to wall, tight into the corners against the painted brickwork.
- Rotten boards and debris cleared back to the joists
- New OSB deck laid across the full roof
- EPDM rubber membrane bonded to the new boards
- Rubber turned up the two white walls as upstands
- Edge dressed over the step down to the lower roof
The finished rubber roof
The final photo shows the new EPDM surface, smooth and dark, turned up both walls with a black band finishing the top of the upstands. On the open side the rubber is dressed over the edge where the roof steps down to its lower neighbour.
If your flat roof feels spongy underfoot, sags between the joists or has stains on the ceiling below, it is worth having it looked at before the deck goes the same way. Get in touch and we will come and see it. For roof problems beyond the flat roof, see our roof repairs in Chester.
Questions About This Kind of Job
How do I know if my flat roof decking has rotted?
Common signs are a soft or bouncy feel underfoot, dips where water collects, and stains or damp patches on the ceiling underneath. Only lifting the covering shows the full picture.
Can a new rubber roof go over a rotten deck?
No. EPDM needs to bond to a sound, dry surface. Laying it over soft boards would leave a roof that sags and moves, and the rot would carry on underneath.
What is the black band at the top of the rubber on the walls?
It finishes the top edge of the upstand, where the rubber turned up the wall stops, so rain running down the wall cannot get behind the membrane.
