Window leaks

30 Nov 2004
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United Kingdom
one of my window leaks when it rains, its double glazed, a small damp patch appears at the bottom corner(but only one corner of the window), i thought i had solved the problem, but it seems to be backed, an just wondering what the next step might be.

Ie replaced the sealent, but today the patch of damp was 3 times the size of what it used to be and am now getting rather concerned

Any help would be appreciated!


It only gets damp on the inside when the rain is heavy for a decent period of time.
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Assuming it’s not an opening window that’s leaking; water appearing on the sill is probably getting through from the outside, either at the top or down the side where the frame meets the wall. Did you replace the sealant on the inside or the outside? If the window isn’t properly sealed against the building fabric on the outside water will get in, run down inside the frame & likely appear on the sill at the bottom.
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Thanks guys

think ive found the solution, i have two windows with this problem, one with an opening.

someone on a double glazing forum reckoned the windows were not sealed properly with silicone at the bottom of the frame:, heres what they said:


I have seen the dampness at the bottom of the plaster line indoors in the bottom corners MANY times, and the reason for it is usually that the bottom of the window frame itself at the extreme edges of the frame were not sealed with silicone to the cill, front to back, when installed.

Therefore any ingress of water past the sealed unit gaskets - worse with lead lights - (which is normal - that is why windows are drained) travels PAST along the bottom corners of the frame (instead of being stopped by a silicone line) going away through either face drainage, or bottom hidden drainage.

Make sure that some uneducated person has NOT run a silicone line outdoors between the window frame and cill, there SHOULD be about a 3mm gap between the two, with concealed drainage. Personally I far prefer face drain...

The cure (maybe a bit of a retrospective cure - but it will work if done properly and VERY carefully), is to remove the sealed unit, drill about an 8mm maybe even a 10 mm hole right through the window frame (so you can ger the nozzle right down) through all chambers at each bottom frame corner, until the drill bit has gone down to on TOP of the cill - NO FURTHER. Take great care about how far you drill!!!

THEN, pump a GOOD portion of silicone in until it comes out of the hole you drilled, effectively and retrospectively doing the job right in the first place.

Drainage water, I reckon, is passing beyond your frame horizontally in the corners and making your plaster wet, because the frame was not sealed to the cill at the extreme bottom corners at time of fitting.

Seen it loads of times, although I could be wrong, I don't think so.


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