Reinstalling French Doors

Having read paulf’s post regarding his window journey I was hoping for some advice on a similar topic. I’m posting in the hope of some advice regarding re-installing a set of French doors with improved insulation & airtightness. They were installed in 2015 by Everest as replacements for original softwood doors with indifferent double glazing that were deteriorating. I wasn’t a happy customer at the time with the quality/installation etc. on multiple fronts. I now have a problem with a previous concrete repair beneath them breaking down and needing repair. I was intending to remove the doors and on refitting improving the installation. Although the property was built in 1998 with partial fill cavity walls, I don’t believe that cavity closers were used so was intending to add these and enclosing the frames with an expanding foam tape, airtightness measures and insulating the window reveals with insulated plasterboard or Spacetherm. The doors are installed to rendered reveals.

However, initial inspection suggests that the doors were installed within an original wooden frame used for fixing through. When I come to reinstall, it looks like I will need to add an outer frame to the current frame to fill much of the gap to allow fixation rather than be able to simply add an expanding foam tape for a small gap. Is there a better solution to minimise thermal bridging? I was wondering If it was possible to use Compacfoam in this situation?

The company’s website talks of extending uPVC window frames so assume also feasible with timber doors:

I’m unsure how to attach images for information

Many thanks

My woeful install of windows and French doors is also Everest, 2017-18. However my French doors are uPVC and do not have a subframe. I am thinking of going with Velfac for the front door.

With the front door in mind I looked into Compacfoam. I my case sunk into the screed floor and solid masonry walls.

I discovered that Compacfoam degrades in UV light, so it will need to be embedded in something. Other than that I have only seen good news about it. Other structural foams are now available, so it might be worth looking at the alternatives.

Sorry I can’t offer more advice at this stage. Please keep us informed about progress in thoughts and deeds.