Basics of preparing openings for new windows/doors in solid brick wall

23 Nov 2021
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United Kingdom
Hello, likely a basic question, but just want to make sure I have it down so we don't make any mistakes!

We are renovating a Victorian property. We will have two windows being replaced - (1)UPVC bay window + (2) existing UPVC opening window being replaced with an alumnium one. And then changing another existing window with a door.
All are in a solid brick wall (so I guess around 220cm wide, approx).

Once our builders have made the openings in the solid brick walls, is there anything else we need to prepare? Do the windows go straight onto the brick, and then we add a bit of insulation internally at the reveals and plaster over? If we did that, I know the frames themselves would be thermally broken so cold from the air wouldn't travel from the outside frame to the inside frame - BUT could cold not travel through the brick from exterior and to the inside frame of the window/door (if the window/door is sitting on the brick), causing a cold internal surface?

Or is there something else to consider, i.e. insulation running the whole length from inside to outside, and then the window sits on that? If so, what sort of insulation would be suitable for both inside and outside in this case.
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The builders, if that is what they are should do everything required to prepare the openings - not just knock a hole in the wall. That will include DPC, sealing any reveals or threshold/cills.

When the frames are fitted they should cover at least half of the reveal (ie back of the frame set back 110mm) to reduce risk of penetrating moisture getting around the frame and local condensation. But as modern frames are not that deep and this can look odd, instead a DPC up the reveal and a thin bit of insulation then plasterboard deals with this.

Building regulations is required for any window install that requires alterations to the surrounding wall, not just a FENSA or other accredited firm.
Thanks @^woody^ - I am sure the builders will know what to do, but I am trying to do my own research to make sure when I speak to them, I am informed and know what to look for. When you refer to DPC in this case, is that just a small piece of damp proof membrane that will lie flat underneath the reveal insulation, on the interior side of the window? I understand how DPC works with new builds, but not super clear how with old properties/existing solid walls.
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Something like this, but with a bit of DPC up the reveal. Ignore the insulation along the bottom of the image


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