Ubiflex vs cromaflex by cromar for velux kerb flashing

[Waseem1]

Hi guys need some advice which is the better flashing material to use on a velux ply kerb. The windows having been installed below recommended pitch and they are leaking. Any advice would be appreciated

 

[^woody^]

Either, non is "better".

But if the windows are below minimum pitch, then that's a different problem.

 

[Waseem1]

Yea they have by the builders on a single storey extension that's why I have purchased the velux kerb. What would be the best material to use on these. I'll attach a photo

 

[^woody^]

Are you fitting it to a flat roof? Normally the flat roof covering is taken up the kerb to make a good seal, and the window flashing kit covers the top edge.

You can't just flash around the upstand without a sealed roof covering beneath it around the upstand. The corners are crucial that they are sealed.

 

[Waseem1]

It's on a low pitched natural slate roof. The flashing will be sealed and a course of slated will be removed around the the timber kerb. Will then install slates butted up around the kerb

 

[^woody^]

You need to be careful with that plan.

The flashing won't be enough to seal water out. You need felt or other barrier which is sealed to your slate underfelt (which in turn should have a ply support board beneath it) and the felt/barrier is sealed up and to that upstand. The corners particularly need proper joints and seal.

Don't just think that you can go around that upstand with flashing.

 

[Waseem1]

Your right.. Appreciate your help
Below the felt there's osb board with counter battons. Was thinking use the ubiflex flashing and should run below the course of slates. Should this be sealed to the breathable membrane