100mm cavity plus something else?

[joe90]

Right, here is a (rough) drawing of what I did (edit to add, forgot to notate timber shaped fillet on top of stainless brackets to hold plasterboard edge next to window ?).

Edited September 6, 2020 by joe90

[Matt64]

That is great - thanks very much for the sketch and your time! 

Out of interest, the stainless bracket for mounting the windows behind brickwork - is it primarily to reduce thermal bridging? Or to help with vertical DPC installation (or both?).

 

I've looked into uPVC typical installation and they screw into the brickwork, so I was thinking of incorporating the vertical DPC as below. bearing in mind I only have 100mm cavity unlike your 200mm. 

[Simplysimon]

as per @joe90 fixing the windows to the rear of the outer leaf does two things, it allows for greater protection from rain, used to be a standard detail in scotland prior to better sealants, still a better detail. the other thing is that it allows you to hide some of the upvc thereby increasing the glazing area. you would also ba able to fix timber to the side of the window for a fiixng for plasterboard, no need for dpc either.

[Matt64]

Thanks Simon, really useful. I like the idea of more glazed area and better rain protection.

Why no need for vertical DPC though? Just because water can't track through the window frame to the plaster?

Cheers.

[joe90]

3 hours ago, Matt64 said:

the stainless bracket for mounting the windows behind brickwork - is it primarily to reduce thermal bridging? Or to help with vertical DPC installation (or both?).

The brackets are there to hold the window to the brick skin, DPC to stop damp within the brickwork migrating into timber etc timber fillet to allow plasterboard to be fixed to the window.forgot to say I used expanding foam gasket on joint between window and brickwork so no ugly sealant to be seen.

Edited September 6, 2020 by joe90

[Simplysimon]

45 minutes ago, Matt64 said:

Why no need for vertical DPC though?

if it were timber windows, then dpc to protect them, pvc ain't gonna rot, nor soak up water. if you fix pvc windows as you detailed, into the external ingoe/reveal, there would be no dpc.

[Matt64]

Thanks very much all for your help, think I've got a good steer on it now. Will post some pics when things get to that point.

[crispy_wafer]

@epsilonGreedy

 

Just reading back through this thread, what method for your cavity and insulation did you opt for in the end?