Are these (leaking) Velux installed correctly?

[sniederb]

We have a roof with three Velux windows which leak under certain conditions. The windows face south, and whenever we have strong winds from the south-west with driving rain, the windows leak. I had a look today and can't tell if the windows have been installed properly or not (very few things in this house have been done properly in the past). "image_1.jpg" shows what the corners look like, to me that indicates water. "image_2.jpg" shows what the window looks like slightly open, and "image3_jpg" shows the front of the window almost closed.

In "image_4.jpg" I've attempted a schematic of what I think is happening. The rubber seal (marked "A") rests in the bottom of a ledge, and that ledge is not sealed towards the outside. There are metal guards covering it, but with proper wind and rain there will be water ingress, which then fills up the ledge (the blue circle), and eventually leaks underneath the rubber seal. "image_3.jpg" shows how there's a gap between window and frame, and the rubber seal which will sit on the bottom of the ledge.

Before I start the creative process of finding a way to seal this ... could someone tell me if these Velux are installed correctly? I can't see anything obviously bent or out of place, but find it hard to believe that this water ingress is by design.

Thanks, Simon

[MikeGrahamT21]

The tiles under the flashing at the bottom of the window haven’t been prepared properly by looks of it, you are supposed to chamfer them to reduce the amount they stick up to increase water run off, this is done at a horizontal plane… hope that makes sense?

 

from a non install perspective, give everything a good clean, and consider replacing the seals

Edited February 15 by MikeGrahamT21

[Big Jimbo]

Looks like you have got a well at the bottom of the window, caused by the flashing being bent up over the tiles below. The water will collect there, and run out at either end into the roof structure. 

I think that your velux windows have been fitted to deeply into the roof structure. 

From memory, they are mounted at different heights depending on what tiles are used.

[sniederb]

2 hours ago, Big Jimbo said:

Looks like you have got a well at the bottom of the window, caused by the flashing being bent up over the tiles below. The water will collect there, and run out at either end into the roof structure. 

I think that your velux windows have been fitted to deeply into the roof structure. 

From memory, they are mounted at different heights depending on what tiles are used.

Thanks for your reply! I believe these windows would be "standard installation" (as opposed to "recessed installation") with an EKW flashing. Looking at the EKW installation guide, I can't make out how the flashing at the bottom is supposed to look like. When the window is closed, that groove isn't that bad (see image), but I'm sure water still accumulates there.

If we have heavy rain, but it's coming down more or less straight, the windows are fine. The leaks are only on almost horizontal rain. I feel this flashing/tile groove would be an issue for all types of rain.

[ProDave]

Can we see an outside picture zoomed out a little or a close up of the detail of the sides from outside?

 

That window should be set about 30mm or so further out from the roof.  It is an installation error.  The bottom flashing from the window should be level with the top of the tiles and then formed to follow the contour of the tiles.  In your case the bottom of the window is recessed too far forcing that bodged bending of the flashing.

 

If it is too low at the bottom then it is probably also too low for the side flashing to work as designed.

[sniederb]

20 minutes ago, ProDave said:

Can we see an outside picture zoomed out a little or a close up of the detail of the sides from outside?

 

That window should be set about 30mm or so further out from the roof.  It is an installation error.  The bottom flashing from the window should be level with the top of the tiles and then formed to follow the contour of the tiles.  In your case the bottom of the window is recessed too far forcing that bodged bending of the flashing.

 

If it is too low at the bottom then it is probably also too low for the side flashing to work as designed.

These are images I currently have, am happy to take more tomorrow if needed. Looking at the one from the side, maybe these are actually a "recessed installation"?

[Jimbobjones]

Next time it is leaking, as soon as the rain stops, open and inspect the edges of the window 
If the bottom frame is wet then the corresponding tracks of water should be present on the bottom edge of the window which would support the hypothesis the wind is blowing the water in

However, if the sides of the window are wet and the water is running down the edge and collecting at the bottom then it is most likely the window cover parts (well it was on my velux which had the same damp spot under bad weather)

[Big Jimbo]

As I previously said, and also said by @ProDave. These windows have been fitted incorrectly.  I stand by that. I have probably fitted in excess of 20 of these windows. The bottom flashing needs to be higher than the tiles below. These windows have been recessed too far into the roof.

[dpmiller]

at the very least, reducing/ chamfering that row of tile under the flashing is required.

[Big Jimbo]

On 16/02/2025 at 09:45, dpmiller said:

at the very least, reducing/ chamfering that row of tile under the flashing is required.

That won't cut it I'm afraid. not enough flashing to enable you to cut enough of the tile away. You will then risk wind blown driven rain. Just have them put right, and have no further problems. Anything else is a bodge, they have been fitted wrong. I will stop commenting on this thread. Seems like a bodge is what the OP is looking for, rather than dealing with what is actually wrong, and putting it right.

[sniederb]

14 hours ago, Big Jimbo said:

That won't cut it I'm afraid. not enough flashing to enable you to cut enough of the tile away. You will then risk wind blown driven rain. Just have them put right, and have no further problems. Anything else is a bodge, they have been fitted wrong. I will stop commenting on this thread. Seems like a bodge is what the OP is looking for, rather than dealing with what is actually wrong, and putting it right.

What confounded me is that there's no bent or loose pieces, no missing screws, everything looking pretty much like it's supposed to be, and yet they leak. So I was hoping to learn if the installation overall is botched or not, and that has been clearly answered. What to do next is a completely different story, I'll have to think about that for a while. My preference would be to replace everything with fixed (=non-opening) skylights, but getting good tradesmen here is rather difficult. At least now I understand the situation, what to do next is a whole new discussion (not for here).

[Big Jimbo]

There is clearly "Bent pieces" The bottom flashings bent up towards the sky before being folded over the row of tiles below the window !

You ask whats wrong. You are clearly told by more than One person..............They have been fitted incorrectly, recessed too far into the roof. Fitted by a muppet. These have not just started to leak. They have been leaking since the day they were fitted. If you don't believe us, send the pictures to Velux. They will confirm "Fitted by a muppet". They will be able to supply you with the hardware and a set of instructions to enable you to have a competent person take these windows out and re-fit them correctly. Scaffolding for access, and a couple of days work maximum.

[sniederb]

14 minutes ago, Big Jimbo said:

There is clearly "Bent pieces" The bottom flashings bent up towards the sky before being folded over the row of tiles below the window !

You ask whats wrong. You are clearly told by more than One person..............They have been fitted incorrectly, recessed too far into the roof. Fitted by a muppet. These have not just started to leak. They have been leaking since the day they were fitted. If you don't believe us, send the pictures to Velux. They will confirm "Fitted by a muppet". They will be able to supply you with the hardware and a set of instructions to enable you to have a competent person take these windows out and re-fit them correctly. Scaffolding for access, and a couple of days work maximum.

Can't help the urge to set this straight ... I'm with you 100%. I'm not challenging any of the statements above. I have zero experience in fitting windows, so I don't have the eye for all the things that have been pointed out. So many things in our house have been "fitted by a muppet", and I feared these Velux would just be another example. Unfortunately they are. As for what next, again I'm completely with you, the right thing to do is re-fit them correctly. The only reason there's hesitation is that we've had quite a few very upsetting experiences with tradesmen here, but that's really a discussion for another day and another place.

Please don't feel like I'm questioning or challenging your feedback. On the contrary, I'm very grateful for the education, and really appreciate you taking the time to answer questions.

[Mr Punter]

59 minutes ago, Big Jimbo said:

Scaffolding for access

 

Can this not be done from the inside?  I doubt they will even need to cut many tiles.  They may need new flashing but I suspect the current ones can be reused.