Window position in cavity

[BadgerBadger]

Hi all,

We're going through detailed design with our architect at the moment and we're aiming for reasonably efficient/airtight construction without going as far as passive.  Wall U-value around 0.13, and windows will be 3G with a U-value around 0.8.

 

Looking at our window detailing our windows are positioned in the fairly "standard" position - mounted to the outer leaf of the wall, with the inside of the window approximately in line with the outer edge of the cavity.  Should I be asking to push the window position further back into the cavity for increased efficiency, or is it not really worth the complexity?  And the silly question if so - how are the windows supported?!

 

Thank you.

[tonyshouse]

I sat my 3g windows in the cavity they were actually slightly larger than the openings and fixed to the outer skin 

 

it is nice to have the windows in line with the insulation barrier. 

[craig]

Very typical of an standard English detail. Sit it further inside. A good early starting point at this detailed stage, is work out where the dew point is.

 

Then you know where the window needs to sit.

[Oz07]

I thought building regs stipulated minimum 30mm overhang into cavity? If I understand you right and inside of your Windows flush with back of brickwork you need to push them in further. 

[joe90]

I used “check reveals”, windows within the cavity fixed to the back of the outer skin, window sat on the outer brick cills (which came back into the cavity a little) Saves having to fill gaps with silicone which can look messy (IMO) stainless brackets and screws and foam tape between window and brick/block.