I have water leaking from two different roof windows. This happens only sometimes which is strange.Depends on the type of rain? The flashing round the windows looks fine and the condition of the tiles on the roof and the ridge looks good. What could the cause of this be? Someone suggested the flashing round the chimney stack could be letting in water but this means the water would be travelling diagonally across the roof. Is there an short term solution other than flashband and lead that i can seal around the chimney stack with? Any help appreciated.

Richard, September 2009

I realise this was 2017 but in case someone else is looking for a similar problem. I appreciate Velux do not guarantee less than 15 degree pitch but I would assume there was a margin for error in this. I have come across Velux at 13 & 14 degree pitches where the angle is only just out for various reasons and WHEN THE INSTALLATION IS FULLY CORRECT THEY DO NOT LEAK. Often it is from another source circling the Velux and usually entering at the eaves above windows, doors etc, and this CAN show leaks, water damage at the Velux as that is where it has drained to. The Velux gets the blame and remedial works then override the issue or do not solve it. Water can track diagonally as it can travel across roof battens and overlaps in the WPL. The shallower the pitch the more chance of sideways or diagonal tracking especially if wind driven at these angles. On pitches of less than 15 degrees we design in a double battens system to allow water to drain vertically without hindrance and this is a spec I always use for low roof pitches. Absolute attention to detail is the key in Velux fitting especially at very low roof pitches. Correct flashing for the tile used and carefully trimming of WPL and dressing into flashings ! Also taking extra precautions in exposed conditions where water can be driven upwards by the wind the very route people/ builders do not imagine water would come from.

Peter D, August 2018

I had the same problems with Velux windows In my kitchen extension. The pitch is 12% so velux won't guarantee them. They did come out and were actually quite helpful. Now that I have got the surveyor to pay for the roof to be re done, which involved them removing the tiles, re boarding and felting the roof, sealing it with bitumen and then putting the tiles, velux windows and the flashings back, you would have thought it might be leak proof - but no. It seems that the velux seals are leaking! Agh! Anyone have a video link to show me how these are replaced? And roughly what they cost? I will be getting the surveyor to pay.... he should have said the roof pitch was so low that the velux windows would not be guaranteed - all very frustrating!

Tess, January 2017

To be sure of what the problem is, I would suggest you look on the top of the window including the header. I can;t see exactly what is on the outside, but I would check that out all the way to under the soffit, to see if there is no water coming in from there.
This link http://www.katyhomeremodelingservices.com/ might help you.

Trishia Hope, February 2013

A build up of moss can act as a sponge and draw water by capillary action.

Give the edges a good clean with warm soapy water before spending a fortune.

WORK SAFE

SwimmingPoolMan, December 2012

I've been dealing with this problem for some time, even got up on a ladder inside and up close during pouring rain. My take is that hard rain bounces up under the window metal lower cover and as the rubber gasket gets old water makes it's way in especially if the pitch is low...

Richard, August 2012

After several months my fix failed (see my previous comment)

So I recently retrofitted my two Velux units, which gave me the opportunity to dissect them for the cause of the leaks.

All evidence suggests that the flashing did its job. The failure was with the sealant under the metal cap holding in the glass. The sealant had dried out and become brittle allowing cracks and gaps to open up and water had leaked into the wood causing rot.

In their defense, Velux has re-engineered the units, though the size of the new units vis-à-vis the drywall is not exactly the same as the old. A bit of a pain for retrofit. I am not sure about differences in sealant.

CedarRoofsRAPain, August 2010

Have had exactly the same problem. Had a roofing engineer over this morning, who diagnosed that the rain is being pushed under the corner of the VRW, in strong winds. Turns out that wrong flashings were installed (EDN rather than EDL) for this pitch of roof (19 degrees).

Nick, November 2009

Maybe too late for this question but can I ask what age these windows are and at what pitch are thay installed at? On the newer VRW's (post 2000) there may be a small gasket missing at the bottom corner below the glazing profile. This can lead to water ingress especially in light rain. This can be easily replaced and should be done by Velux, under guarantee. Ensure the installation has been carried out correctly before contacting Velux, the current policy is to try to bully customers out of making guarantee claims by suggesting that ther will be a call out charge where installations are incorrect.

Velux Helper, November 2009

Not sure if this is similar, but my Velux leaks seem to originate between glass and metal at the lower (downslope) edge where water collects, discoloring that part of the wood with occasional drips into the house. Since the flashing and pitch (5/12) is adequate, I figured it was a Velux problem.

So onto the roof I went. After I meticulously cleaned the small amount of moss and needle debris from these areas and drying, I applied a thin continuous bead of clear silicone where glass meets metal and at the lower miter corners which had small separation gaps, and smoothed it out making sure all seams where covered. It’s rained a few days since and so far so good... no sign of moisture.

And yes, I’ll probably have to check (and possibly redo) this fix as often as I clean the skylights – twice a year. Outside of disassembling the unit and resealing the glazing I don’t know what else to do.

CedarRoofsRAPain, October 2009

there are many problems with velux windows; is the roof pitch enough and the tiles plain? velux cant be fitted properly with profiled tiles

plumbersw15, October 2009

This is just a guess in reference to how the frame make up disperses the rain.

Back flashing under tiles sends the rain to run in to purpose integral formed gutters at side of the frame then continues on to the front apron flashing which should be set OVER the roof tiles it then continues over the tiles eventually into the main roof gutter at the eves. The gutters on the side of the Velux frames may be obstructed with moss lift side tiles and look. I say this on having a roof job many yrs back when that was the problem blocked with a lump of moss growing in the gutter so diverted rain over the gutter into the roof void down rafters on to ceiling. When you say certain rain my thoughts are certain wind directon.

Good luck hope this helps.

Bob, October 2009