Under-slate membrane > sealing a Velux

antiskeptic

Roof slates going up but not completed, rain falls, runs down Tyvex ... and into house where Veluxs have been installed.

Roofer says you can't actually seal against this and points me to the installation instructions.

And he would appear to be right. How do you cut the membrane into each of the 4 corners (per Velux instructions) and lap it up the perimeter battens without leaving yourself open to any water, which has gotten under the slates upstream of the Velux, running down to the top crossways batten, along the membrane upstand and over to the corners ... and into the building via the entry point shown by the yellow arrow .

Then again, I can't imagine a co. like Velux not attending to such an obvious issue.

Any ideas?

brophis

antiskeptic wrote: »

Roof slates going up but not completed, rain falls, runs down Tyvex ... and into house where Veluxs have been installed.

Roofer says you can't actually seal against this and points me to the installation instructions.

And he would appear to be right. How do you cut the membrane into each of the 4 corners (per Velux instructions) and lap it up the perimeter battens without leaving yourself open to any water, which has gotten under the slates upstream of the Velux, running down to the top crossways batten, along the membrane upstand and over to the corners ... and into the building via the entry point shown by the yellow arrow .

Then again, I can't imagine a co. like Velux not attending to such an obvious issue.

Any ideas?

Had something similar with my roof windows. Mine were Keylite and they sold an extra to resolve this issue. Don't have the details handy but should be instructions on their site.

esox28

Course you can, with airtightness taping.

The roofing membrane should have been taped to the Velux to stop wind blowing throughand into your rafters below which would have stopped rain getting in.

Hope this helps and not too late.

antiskeptic

esox28 wrote: »

Course you can, with airtightness taping.

The roofing membrane should have been taped to the Velux to stop wind blowing throughand into your rafters below which would have stopped rain getting in.

Hope this helps and not too late.

Get the sense of it, but not sure it deals with the specific issue of the OP

It's the route of water shown in the photolink in the OP I'm concerned about - rather than wind borne rain generally.

I don't see how you'd successfully apply tape (even a waterproof tape) right at the root of the cut corner once the Velux is installed and your lapping the cut pieces. At it's right at the root of those cut corners that the water would heading inwards at.

North West

Hi go to this site all details here. Read it all as drawing you put up is only the start more to do . http://www.loftsolutions.co.uk/help/how-to-fit-a-velux-window
Nw

antiskeptic

North West wrote: »

Hi go to this site all details here. Read it all as drawing you put up is only the start more to do . http://www.loftsolutions.co.uk/help/how-to-fit-a-velux-window
Nw

FFS. So my slate roofer is a slate roofer...

Thanks NW..