I have large UPVC windows which were installed long before I moved in 4 years ago. The first winter downpour revealed a small waterfall trickling down the right hand side wall return that the window is set in. A quick look showed traces of damp in the ceiling cornice and the wall below the the window had blown. Also the corresponding window above had similar water coming in. We think it is coming from the top window after a hose test.
We have had UPVC seals checked. Had the white plastic cladding on the fascia taken off and the felt and leading replaced. The roof has also been looked at and the walls which are a bath stone composite have been sprayed with a sealant.
We are at a loss as to where the water is coming from, any thoughts or something we may have missed???
Had similar problem with some old PVC Units. Eventually found that they didn't have breather holes outside to allow trapped water to trickle out onto windowsill - Trapped water built up and eventually found way into house. Couple of quick drill holes late and no more leaks. :)
You have three possible events.
A leaking roof. Go up into the loft and check out the roof using a bright lead light, lay on the floor and get as close as you can.
Water can enter a roof and run a long way before it shows, it may be running down a rafter and entering the cavity wall if you have one.
Wind blown rain can hit exposed walls and roofs with the force of a bullet, far harder than the water out of a hose pipe. It can blow up hill, it can blow through solid walls. Think about this, does the water come through when the winds blows from a particular direction?
Not all windows are fitted as well as you may expect. Wind blow rain may be finding its way in round the frames.
lack of drainage holes could def be a problem. i came accross a window problem with white ali frames. although the seals we ok. for some reason water was entering between glass and seal by capillery action and being drawn into the middle of the frame. drilling drainage holes did help but in order to erradicate completly i installed a wide drip moulding over the top of the frames to re-direct and keep the majority of rain off. drastic i know but apart from replacing all frames, the next best thing. this was done 5 years ago and is still working.
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