Windows - Help!

[HEB1]

Having hovered over the site for the last 2 years - we now have our SIPS kit largely assembled up on the Outer Hebrides.  We are aiming for high detail on airtightness and will be cladding it in 12mm thick Cedral Click on a 50mm timber batten

 

A recurring theme I remember reading on the forum is 'windows, it's always the windows'. Following the predictable " leave it to us, don't bother with air tightness" conversation - our lovely Rehau windows are in:

 

My concerns are,

 

1. 50mm of the 70mm frame is sticking out of the cavity (although from inside they look great) 

2. Should the window cills be sitting directly on the VCL/Breather membrane in the cavity with nothing to prevent water/air ingress? - I had assumed at least a bed of silicone?

3. Our entrance doors are due to be similarly fitted this week.

4. Gaps of only 5mm on 3 sides of openings 

 

I had planned on using Compriband on the outer edge with low expansion foam on the inner  (as specified) with the windows flush with the outer edge of the cavity, I had ordered 180mm cills specifically but 150mm cills have been supplied.

 

Photos also attached below show standard practice up here to have the firestop flush with the outer edge and tight up against it for ease of cladding the reveals but is this good enough?

Gaps are squirted full of silicone.

 

Any help would be appreciated as glazing yet to be fitted in the large windows.

 

 

 

IMG_9434.pdf IMG_9447.pdf IMG_9442.pdf IMG_9451.pdf

[ProDave]

Foam the gap between windows and frame and then tape the window to VCL layer with air tightness tape.  And tape over the leak points like those window retaining brackets.

 

You have some work to do something sensible with that wall to eaves "joint"  Is this room in roof with insulated roof or just a single storey with insulated ceiling.  There may be a lot of work getting the roof or ceiling insulated properly and air tight.

 

If the cills ordered have been delivered short, reject them.  The cill usually goes in a groove in the bottom of the window frame and the outer edge must overhang over the outer edge of your cladding.  If it won't then it is too short.  Some window suppliers don't make them big enough and they have to be fabricated by someone else, and is supplying short ones them hoping you won't notice and they can avoid the expense of getting them made to spec?

[HEB1]

Thank you for the tips,

 

Would you not bother with compriband? (joiner said even window grade foam will distort the upvc frame which I can't believe)

 

It will be room in roof and I will be asking for the 180 cills ordered as can then set window back a bit further

 

 

Many thanks