Velux Window Installation

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I have 3 velux roof windows (GGL style) installed in a newly built room. The
roof is a standard wood rafter construction, felted and tiled. The felt and
batterns were put on the roof before the velux went in. The velux flashing
then went on, then the tiles. Around the edges of the velux installation,
the roofing felt was tucked into the window aperture, then the velux fitted.
Problem we have now is some water leakage around the edges of the velux. It
is running down on the felt that was tucked in. Now I know firstly that if
the tiling has been done properly there shouldn't be any leakage through
onto the felt, that is one problem to sort out. However, if any water does
get passed a tile onto the felt, then this should run down and of the felt
to the bottom of the roof. The way the felt was tucked into the aperture
does not seem right, especially above the Velux, as the felt does not
overlap the top section of velux flashing, meaning if any water on the felt,
runs down to the velux it goes under the velux flashing, then into the room.
the builder assures me it is the correct installation and that once the
leaks passed the tiles are sorted out then there will be no problem. the
information on the velux site and the brochures I have are not very clear.So
am I right in saying the roof felt, especially at the top of the velux
should overlap outside/on top off the velux flashing?
 
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The roofing felt should be folded up the sides of the velux before the flashings are fitted on all four sides. It sounds in your query that they have tucked the felt downwards into the velux apeture. Ideally the felt should go over the rear flashing but the flashing sits on top of the laths so it cant be done. folding the felt up the sides will form a gulley for any water getting on to the felt to find its way around the velux.
 
yeah as above. i did mine the other month and thought long and hard where water could get too even in the wind and put extra felt in as precaution in certain spots.
Id say get them to change it for the long run...

24092006137.jpg

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I think the Velux instructions (which aren't great) show a roofing felt 'nappy' being installed around the window to stop water getting in as described. This was how I installed the Velux's in my last house.

However the Builders installed the Velux's in my new house in exactly the same way as yours. When I queried it they said that the tiles and flashing should keep all the rain off - and so far they have been right.

So basically the way they have been installed seems quite common in the building industry, but doesn't meet Velux's instructions. If you've got water coming in, then get them back.
 
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the builder assures me it is the correct installation and that once the
leaks passed the tiles are sorted out then there will be no problem

I have installed two velux windows at home - one in the original roof (pitch 32 degrees) and one in the extension (pitch 22 degrees). Both of these were left during very heavy rain with just the felt and no slates and I didn't get any leaks whatsoever. This included a howling gale to really test that everything was weathered (i.e. sealed) correctly.

Just one other point... do you know if the correct flashings have been used? There are a few different types available for slates, tiles etc. and whilst this has no real effect on the weatherproofing it does have a definite effect on the finished appearance.
 
I have 3 velux roof windows (GGL style) installed in a newly built room. The
roof is a standard wood rafter construction, felted and tiled. The felt and
batterns were put on the roof before the velux went in. The velux flashing
then went on, then the tiles. Around the edges of the velux installation,
the roofing felt was tucked into the window aperture, then the velux fitted.
Problem we have now is some water leakage around the edges of the velux. It
is running down on the felt that was tucked in. Now I know firstly that if
the tiling has been done properly there shouldn't be any leakage through
onto the felt, that is one problem to sort out. However, if any water does
get passed a tile onto the felt, then this should run down and of the felt
to the bottom of the roof. The way the felt was tucked into the aperture
does not seem right, especially above the Velux, as the felt does not
overlap the top section of velux flashing, meaning if any water on the felt,
runs down to the velux it goes under the velux flashing, then into the room.
the builder assures me it is the correct installation and that once the
leaks passed the tiles are sorted out then there will be no problem. the
information on the velux site and the brochures I have are not very clear.So
am I right in saying the roof felt, especially at the top of the velux
should overlap outside/on top off the velux flashing?
 
I have 3 velux roof windows (GGL style) installed in a newly built room. The
roof is a standard wood rafter construction, felted and tiled. The felt and
batterns were put on the roof before the velux went in. The velux flashing
then went on, then the tiles. Around the edges of the velux installation,
the roofing felt was tucked into the window aperture, then the velux fitted.
Problem we have now is some water leakage around the edges of the velux. It
is running down on the felt that was tucked in. Now I know firstly that if
the tiling has been done properly there shouldn't be any leakage through
onto the felt, that is one problem to sort out. However, if any water does
get passed a tile onto the felt, then this should run down and of the felt
to the bottom of the roof. The way the felt was tucked into the aperture
does not seem right, especially above the Velux, as the felt does not
overlap the top section of velux flashing, meaning if any water on the felt,
runs down to the velux it goes under the velux flashing, then into the room.
the builder assures me it is the correct installation and that once the
leaks passed the tiles are sorted out then there will be no problem. the
information on the velux site and the brochures I have are not very clear.So
am I right in saying the roof felt, especially at the top of the velux
should overlap outside/on top off the velux flashing?




i have just attended the velux fitters course at kettering and your problem is that you need to fit the collar and drip rail. it costs about £20.00 The collar fits around the window and is stapled to the wood of the window frame. The drip rail is then positioned just above the top of the window and the felt and the collar is wrapped around the rail and clipped into position hence all water is redirected into the rail and away from the window and down the felt some 8 to 10 inches away on either side of the window frame. easy to fit you just need to remove a few tiles above and around the window.
 
three reason why it might leak..
Felt really is not important provided the flashing kit is correct and tiled in correctly.

1/ check all screws have been fitted to trims.
2/ roof above velux is faulty
3/ it's been ****ed up.
 

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