Hi all.
3 years ago we built a single storey rear extension with a flat roof. It was a parapet roof, with capping stones, finished in a light thru-colour render. Like this:
It looked great at first, but after a short time some issues became apparent. Firstly the capping stones didn't really protrude far enough from the face of the wall which meant rainwater just ran down the face of the wall rather than dripping away freely. Secondly, the mortar between the capping stones quickly washed out, staining the wall and increasing the problem of water running down the wall. This has led to staining, and in one case a crack in the render:
The company that did the render have been back once to patch up but have said, quite fairly, that until I sort out the issue of water running off the roof and down the wall, they won't come back again.
So I need to do something. The options I have come up with are:
1) A second layer of coping stones, corbelled off the existing ones and protruding a further say 15cm (the stones are 400mm wide).
2) A retrofitted fascia board.
For 2 - not really sure how to do this. The image below shows how I might attach lengths of U-shaped metal that I could get made up. They come in 3m lengths so I would need 4, and they would need to overlap. I envisage fitting them right up underneath the existing capping stones. I am thinking that I could fix two battens to the wall - one to take the top lip and one to take the bottom lip. I would then slot the metal "fascia" over the battens and fix with roofing screws from top and bottom. I'd silicone between the capping stone and the metal, and probably the render too. I would have to find a way to put an end cap on as well.
Does this sound sensible? I am a bit concerned that there is no drip on the U-shape, although I could try to get one added by the company that would do the manufacturing.
And am I missing something obvious? Are there ready-made systems out there that I am overlooking?
Any help would be much appreciated.
3 years ago we built a single storey rear extension with a flat roof. It was a parapet roof, with capping stones, finished in a light thru-colour render. Like this:
It looked great at first, but after a short time some issues became apparent. Firstly the capping stones didn't really protrude far enough from the face of the wall which meant rainwater just ran down the face of the wall rather than dripping away freely. Secondly, the mortar between the capping stones quickly washed out, staining the wall and increasing the problem of water running down the wall. This has led to staining, and in one case a crack in the render:
The company that did the render have been back once to patch up but have said, quite fairly, that until I sort out the issue of water running off the roof and down the wall, they won't come back again.
So I need to do something. The options I have come up with are:
1) A second layer of coping stones, corbelled off the existing ones and protruding a further say 15cm (the stones are 400mm wide).
2) A retrofitted fascia board.
For 2 - not really sure how to do this. The image below shows how I might attach lengths of U-shaped metal that I could get made up. They come in 3m lengths so I would need 4, and they would need to overlap. I envisage fitting them right up underneath the existing capping stones. I am thinking that I could fix two battens to the wall - one to take the top lip and one to take the bottom lip. I would then slot the metal "fascia" over the battens and fix with roofing screws from top and bottom. I'd silicone between the capping stone and the metal, and probably the render too. I would have to find a way to put an end cap on as well.
Does this sound sensible? I am a bit concerned that there is no drip on the U-shape, although I could try to get one added by the company that would do the manufacturing.
And am I missing something obvious? Are there ready-made systems out there that I am overlooking?
Any help would be much appreciated.