I've got a problem, when the there is a combination of wind and heavy rain I get water pouring through the top of my window int he sitting room. I've taken the surround off,a nd can only find evidence if it come from above. There is no gaps in the silicone around the window frame.
The house has a cavity wall structure, with cavity wall insulation (retro fitted). The outside is rendered, and after an extension was built the render was put over the old render, so its effectively doubly think on the wall in question. I find it unlikely that it would go through both, and the brick work.
Directly above the window in question is the bedroom window, which suffers no problems. The bottom side of the window does appear to have a bit of a draft, could the water be being forced under the existing / old outer window sill?
I'm assuming that the water is travelling through a join in the cavity wall insulation, and coming out at a point roughly halfway across the top of my window downstairs.
The tiles on the roof are new (nothing else was replaced) after the also after the extension was built, and its not damp inside. The soffits look ropey, and were not done hugely well, could this be where the water is getting in? or is it more leakly to be coming through the wall, or through the underside of the upstairs window?
Luckily just now there is no damp inside, other than when the drips end up splashing water down the wall inside and onto the floor (a pain, but not as bad as it could be!!).
You seem to have eliminated water getting into the wall so the most likely cause is that water is running down the render and is then being blown onto the top of the window frame and in. I assume that a renderstop drip moulding has not been fitted above the window.
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