SLABdan

Thank you for the reply. The windows are uPVC, around 30 years old and have lots of issues; screw holes through frames (for blinds), some not sealing brilliantly and to be honest they look terrible also. If I’m honest I care less about co2 footprint and more about performance long term comfort that triple glazing will give me.

Thank you Mike, will check those all out

Reveals already insulated all the way around, everything is finished besides the old windows!

This is the window section. Hatched areas are PIR. Green lines are airtight tape. Blue are concrete fixings. Cavity wall insulation also in there currently.

Hi all, Long time lurker here! We're approaching the end of our retrofit of a 1960s house. Full IWI, membraned, battened, taped, MVHR, the whole lot. However, we didnt have enough funds for new windows at this phase so an exec decision was taken to progress and a few years down the line swap them out. Now I have a dilema (a nice one), our financial position has changed so we're in a position to replace, the only problem is that the old windows are taped in, insulated reveals and now skimmed 😅 Besides slicing the airtight tape tight to the old window and splodging in a tonne of airtight sealant during installation (masking my nicely skimmed reveals) does anyone have any other ideas. I'd prefer not to reskim every reveal (my plasterer - family friend will kill me). Other option I was thinking about was a timber lining to each? Any pearls of wisdom amongst you clever folk?