leaking velux window

hi, did you ever do any drawings or take pictures? I have a similar problem and for the life of me can not find the leak. Endless hours and jugs of water spent but to no avail. If you did drawings or had a picture I would appreciate seeing them. Many thanks.
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My leaking GGL104's turned out to be condensation forming on the rubber (?) seal and running out. I think anyway. Because, in the summer when it rained i had no leaks. Winters back, and the bloody things are covered in condensation on the glass but also if you look closely at the rubber seals (shine a torch into the gap between outer frame and window frame) you see droplets on the rubber.

Anyone know if newer designs are better in this regard, or indeed if there is a solution?
There is in all probability an easy fix to this. This leak (bottom left/right of the window rather than the frame), does not happen on steeper pitched rooves, it starts to appear when the pitch is approaching the minimum recommendation. On the frame, at the top of the window are two flashings, secured by one screw. This flashing overlaps the second pair of flashings that are fixed to the window itself, with two screws. Loosen the screw to the frame flashing and remove the screws fir the window flashing. The window flashing can then be removed by a gentle downwards tug, towards the base of the frame. Once removed you should be able to see a flat u-shaped gutter on the window frame. This will have some debris in it so clear that. You will note that the gutter allows water to run from the side of the frame away from the window at the base, but look closely and you will see that there are gaps going into the window frame itself around the bottom end of the gutter. These don't matter on a steep pitch but if there is any debris under the window trim or the rain is coming in at a shallow angle in a wind, the water can back up and go through these holes. On a dry day, brush away the debris, fill the holes on either side and along the bottom of the u-shaped gutter using exterior transparent silicone sealant and that problem will be fixed.

Oh, and do the other windows that aren't leaking at the same time. ...
We have the same issue as a lot of people on this group, a leak from the bottom corner.

I have attached a photo and it seems like there is a bent piece at the bottom of the frame. I'm not really sure what I'm looking for but could this be the cause?


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Just had a conversation over several days with "experts" at Velux on this same issue. They came up with various suggestions which I won't dicuss here but I think greenhout is on to something (above). I noticed that a particular screw holding the outside covering to the wood had obviously not been driven completely in and was standing a bit proud and was not at a true 90 degree angle. I thought that might prevent the window from closing properly and so corrected it. Also there was a fair bit of detritus in various places including around the black foam sealing piece at the top of the frame all of which I thoroughly cleaned out. Now yesterday it rained and "blew" all day and I am pleased to report that no drips appeared. It is often quite amazing where wind driven rain can get into, I previously owned a house in an "exposed" location where despite various reparations to lead work and the application of various "waterproofing" materials would still leak around the chimney if wind driven rain kept going for a few hours. An old and experienced roofer finally nailed it - "You've got one or more porous bricks up there, get the chimney stack rendered and it will stop. Have a look around - you will see lots of rendered chimney stacks." He was right, I paid him £60 to get it done which took him a couple of hours or so and the leaks stopped.
The rubber seals on the window need cleaning now and again because moss & algee build up can lead to the window weeping water through the seals especially at lower pitches.
I,m basically just confirming what Greenhout has said.
Hi there, I’ve got a similar situation. Posting this so that it hopefully helps.
There’s a gap on the end of the Velux under the flashing and when there is heavy rain and wind then we have a considerable leak. I assume the rain runs down the gully on the side of the glass and then gets blown into this gap under the flashing that runs all the way down to the inside corner of the velux. I cleaned all this up and took all the botched fix silicone off (in the pic - its not where the leak was) and daubed copious amounts of CT-1 in the gap, leaving a channel for the water to run down. It has been bone dry since.
I have a 4 year old centre pivot velux window and has started to rain in .It only happens when it is heavy driving rain .It is leaking in from the bottom left hand corner,When checked further it appears that the left hand side inside framework had water on it,but cannot find how it is getting onto it and making its way down to the bottom corner.


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The rubber seals on the window need cleaning now and again because moss & algee build up can lead to the window weeping water through the seals especially at lower pitches.
I,m basically just confirming what Greenhout has said.
I can confirm a simlar experience recently: During a period of heavy rain/wind started to get drips coming through around a light fitting. Mrs got all worried about "electricity and water" despite my assurances so I looked out of bedroom window (the veluxes are installed on a rear extension. I could see rain "puddling" around some moss and detritus so got a long stick and poked same out of the way. No leaks since.
Leaking GGL MK04 - Fixed, I think.

Window slope 15.0 degrees. eventually discovered that there was a tiny gap between the aluminium frame cover and rubber at the bottom of the frame. (Maybe the rubber weathered a bit to produce the gap?). Silicone sealant applied which appears to have fixed the problem.

My Velux Leak.jpeg
Another discovery which may help some: I though I had everything fixed but another incident occurred recently due to a quite rare combination of events. But let me begin with a few thoughts:- Why do yer ordinary "vertical" DG windows never leak? - 1. They are vertical, 2. The installers bung a thick bead of sealant all the way round and 3. When closed the frames are pressed tightly against the rubber seals. If you still have some old style wooden windows as I had in one house many years ago, you will know that if such a window faces west and there is a gale combined with heavy rain, sometimes some rain will get in. THAT IS THE ISSUE which some of us are facing here so "pouring jugs of water down" never finds a leak. So back to my "discovery":- Last week the rare combination of events was a south-easterly gale and heavy rain which again caused a leak - the roof we are talking about faces south-east BTW and has four veluxes but only one was leaking. So I ask myself what is different about that particular window vs the others? I stared at it from above but cannot see anything obvious so give the local velux man a call who promises to come and look next week... Next day it's dry and so I am outside and decide to look upwards to that roof and veluxes for no particular reason. Suddenly it's obvious! It ain't the veluxes at all, it's a couple of the surrounding tiles which are not laying completely flat as they should be but have gaps of 3 - 5 mm beneath them such that the rain/wind combination from a particular direction can blow water up through said gaps. It doesn't happen most of the time because the wind is usually from the west or south-west and therefore at the wrong angle to blow water ito those gaps. Velux man agrees, gets up there and bungs a bit of sealant in said gaps. The moral of the story is of course that veluxes are not "vertical with sealant all round" and that's why they won't gurantee no leaks as one gets closer to the horizontal, i.e., below 15 degrees. Also if you have a velux installed try to ensure that your installer has done a velux course where they explain necessary attention to detail of these kind of things.

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