I had a flat roof renewed with rubber (from felt) 3 years ago, and it started to leak through to the room below, quite substantially.
There was no flashing put to the wall adjoining the flat roof and after calling the builder who did the roof, he painted some sealant about 6'' up from the roof saying he thought it was getting in there, not that the roof has failed. It is still leaking and the ceiling below has now collapsed, he now says maybe its the render on the south facing wall (above the flat roof) that has failed..and he will paint something on that but doesn't come to do it.
Is there something I can 'paint' on it to stop it as I am worried the boards underneath are going to go rotten.
there isnt any flashing, he just came back and painted some sealant on first few inches up from flat roof.. and doesnt look like he's coming back to do any more. So is this something that I will need to do to stop the leak?
If the roof is sound and an upstand has been formed where the flat abuts the wall then yes you should get a flashing fitted. This needs to be cut into the wall by at least 25mm.
If there is no upstand then one needs forming with the bottom of the upstand bonded to the flat roof.
If you havn't already got one, buy a SDS drill or angle grinder. Use it to channel out the wall, cut away about an inch or so of mortar along the upturn, tuck a lead flashing into the gap, hold in place with lead wedges fold it down over the upstand and repoint.