Can a window be installed in the middle of a cavity wall?

[oculushut]

We have a window frame where the top course of bricks on the outer wall is made up of bullnosed bricks.

Something like this:

We have bought a window and the installation has not completed yet. The window has been installed on top of the outer wall. Like this:

From the inside:

It looks kind of strange now (at least to my eyes) since there is now a gap between the sill and the bullnosed course of bricks.

I would prefer it if the window was positioned more towards the centre of the wall like this so the bullnoses can be seen:

I believe that this can be achieved by adding some wood into the cavity fixed to the breeze block like this (shown in red) so the window can then be attached to this wood:

Our builder is looking to see if this is do-able... there are some concerns around building control, thermal bridging and the wood rotting away in the long run...

Are there any common solutions for this kind of thing?

Thanks!

 

[Notch7]

Are there any common solutions for this kind of thing?

Usually such windows just sit on the external brickwork and are secured on the sides with straps. Sides should have cavity closures as nirmal.

If I had made timber windows for this situation I wouldve made a stub cill, that left just a 10mm gap down the the bullnose brickwork.

The cill detail needs to be done carefully to ensure correct weathering, as its vulnerable to water ingress.

If your window is upvc maybe the cill could be omitted and a packer and trim used instead. Bear in mind the frame would need face drainage.

 

[oculushut]

Usually such windows just sit on the external brickwork and are secured on the sides with straps. Sides should have cavity closures as nirmal.

If I had made timber windows for this situation I wouldve made a stub cill, that left just a 10mm gap down the the bullnose brickwork.

The cill detail needs to be done carefully to ensure correct weathering, as its vulnerable to water ingress.

If your window is upvc maybe the cill could be omitted and a packer and trim used instead. Bear in mind the frame would need face drainage.

Thanks for ideas. The frames we have are aluminium. Will see if the cill can be omitted as you have suggested. May have to just live with it if that does not work...

 

[oculushut]

Does anybody have experience installing an Origin OW70 frame? We have a 95 cill on it. Would be good to understand if this is actually detachable...

 

[oculushut]

Heres what we have right now...

 

[oculushut]

In case anybody has the same question in the future: you can remove the cill onsite, but this requires the whole window to be removed.