Window Position and Fixing in Stone Clad Timber Frame

[James1234]

Just getting started erecting the timber frame of my extension (timber frame and 125mm stone cladding) and having a discussion with the builder about how I want my windows positioned and fixed.

 

Options being:

1) windows positioned forward and fixed into the stonework cladding (traditional approach but issues with cold bridging) 

2) front of window frame at back of stone cladding (reduces cold bridging but seal between windows and stonework more vulnerable and not sure how windows are fixed)

3) set into the timber frame with some sort of flashing to span the gap between stonework and window frame

 

Option 1 seems like the least preferable,

Option 2 does the fixings go into the cavity closer or off brackets back to the timber frame? Is the joint to the stonework achieved with mastic or are the other options?

Option 3 seems like an additional complication

 

Interested to hear how others have done this. Sketch of my understanding of option 2 below.

[James1234]

A variation on the theme is the detail for the patio sliding doors of how to fix to the steel goal posts while minimising cold bridging. Any recommendations on how I can improve on the below attempt? (both this and previous sketches are of the side of the window)

 

[ProDave]

Option 2, pictured in your first post, is the standard way of fitting windows in brick / block / stone clad timber frame houses in Scotland.

[craig]

[James1234]

Many thanks ProDave and Craig, very much appreciated!

[daunker]

Sorry to bring up an old thread, but I am positioning my windows. And having similar dilemas.

 

Why wouldn't you pull the windows say 30-40mm forward in the first post such that they can be sealed against the stone, but still are fixed on brackets to the timber. The window depth would still overlap the cavity and timber frame and insulation. A compromise but insulation would still overlap so not a horrendous cold bridge. It's what I was planning to do so surprised no one suggested or is there a reason I'm missing?

[Mr Punter]

9 minutes ago, daunker said:

Sorry to bring up an old thread, but I am positioning my windows. And having similar dilemas.

 

Why wouldn't you pull the windows say 30-40mm forward in the first post such that they can be sealed against the stone, but still are fixed on brackets to the timber. The window depth would still overlap the cavity and timber frame and insulation. A compromise but insulation would still overlap so not a horrendous cold bridge. It's what I was planning to do so surprised no one suggested or is there a reason I'm missing?

 

The timber frame will shrink as it dries, moving downward compared to the stone, especially on upper floors.  The detail needs to accommodate this differential movement.  Compriband sealing tape is often preferred over mastic as it offers more flexibility.

[daunker]

Yeah so mine is a single storey so only like 3mm differential. The tolerance is 12-15mm and sealed with that expanding tape you refer (keep cool before use). It's what velfac recommend. So I think it'd be grand. Just surprised no one suggested it above?