Roof Window/Skylight Upstand & Tilt Fillet

[STORYTELLER]

Hi

Hopefully an easy one - hard to find info online.

I am making upstands myself for a new roof extension with skylights. 2 x 1.2x1.7M skylights.

This is my amateur 3D model of the upstand.. shows indication of VCL in yellow lapped up the side above the top deck/insulation/EPDM

and have built as below. Ignore gap at bottom... its intentional as a thermal break...

Just looking to check where the lapped up VCL should stop - I'm guessing behind the Tilt fillet? Which is my next questions - how important is it? how big should it be? and should it be hard fixed to top deck (OSB) and the ply upstand? or does that stop the expansion movement of the top deck too much?

any input much appreciated!

Also as a note, my builder seems to want to use 10/11mm OSB on the roof deck! Surely it's 15mm minimum @ 40cm joist pitch!?

 

[noseall]

Also as a note, my builder seems to want to use 10/11mm OSB on the roof deck! Surely it's 15mm minimum @ 40cm joist pitch!?

We use x2, 11.5mm OSB deck sandwich i.e. joists - furrings - x1 layer of 11.5mm - 150mm insulation - another layer of 11.5mm OSB....

barn3.jpg

• noseall
• 21 Oct 2023

lan.jpg

• noseall
• 18 Nov 2023

 

[STORYTELLER]

We use x2, 11.5mm OSB deck sandwich i.e. joists - furrings - x1 layer of 11.5mm - 150mm insulation - another layer of 11.5mm OSB....

barn3.jpg

• noseall
• 21 Oct 2023

lan.jpg

• noseall
• 18 Nov 2023

do you use tilt fillets? are BC OK with 11.5? as LABC/NHBC etc guidelines say min 15mm @ 40cm joist centres? also where is the Vapour layer there? cant see it lapped up the upstand?