Recessed velux help please

[Lightman]

Hi there,

I want to install some Velux windows on a fairly shallow roof. One side is 32 degrees and the other is 30 degrees. The roof is slate

The Velux recessed velux flashings for slate are "EDN flashings" but Velux specification is that they can only be used to down to 35 degrees

As one side of my roof is only 3 degrees out of spec I can't believe it wont work!!! Velux tech support say "don't do it" but can't really explain why not! I can understand why they won't recommend anything out of spec but I'd like to understand what the risks are?

I'm willing to try a calculated risk!!!

As the window is flush (and the flashings are recessed) the bottom of the flashing has a tray to drain or "kick" the water out. This obviously could fill up with water if the angle was too shallow but surely I could bend this a little more just so water does not pool at the bottom?

I agree it would be silly to use it at say 25 degrees but 32 and 30 degrees must be possible (only 3 and 5 degrees out of spec!!) Velux must allow some margin for error.

The final comment is the roof windows are only 1 metre from the ridge so won't be dealing with huge volumes of water. If the contraint was the how quickly water could drain from the side gutters this fact could be quite relevant (ie if they are quite flat then the water could overflow over the top of the side "secret" gutters

Has anybody fitted these recessed flashings?

Thanks - Lightman

[Tony Bryer]

The key issue is probably what happens when the wind is driving the rain up the slope. And Velux's figure is probably the worst case situation, so if you are in a more sheltered area you may well be OK

[keith_765]

Which type of Velux window do you propose to use.?. If they are GGL combined with a slate roof a EDL flashing kit is used which goes down to 15 degs.

[Jim Alexander]

You could download the CAD file from Velux (pretend you are an architect) and measure the angle of the bottom tray from the drawing.

The bottom flashing is one piece with upturned verges so bending is not a trivial excercise.

Yes, in an approx 36deg pitch roof. There is not much slope left on the bottom tray

Jim A

[auctions]

EDL are the recessed version. EDN are also for slate, and work in 15 degree slopes. Do you really need to recess the windows that much?

An alternative is to look at Fakro windows - the quality is as good and they are cheaper, plus they do 3 levels of flashing, so you could use the intermediate position.

A

ps - I guess the problem with the recessed ones is that the bottom flashing, if the slope is too shallow will end up with the edge in contact with the window lower than the edge in contact with the slate. You'd need to bend the bottom down to fix that, and then it wouldn't fit to the slates correctly.