Time to get on with it...

The no nails worked yay, so the wall has bonded to the timber. There is a couple of areas not gone so well, small patches, so a run of gorilla glue in and all is done.

Now here I apologise for the lack of photos as I go but I'm working on my own and i forget to do it as I go as I get engrossed in what I'm doing.

Well after some deep thought, I decided on the interior finish of 5mm ply with fablon covering. The existing wall is like 3mm cardboard with wallpaper on so only a 2 mm difference and careful measuring shows that the window seal, which have now arrived, will fit over this. The timber I sourced from Champion Timber Supplies who cut the sheet of ply to overall size for me

I cleaned up all the window edges with white spirit and degreased all of them with methylated spirit. The interior wall was in 3 sections, 2 outer identical and a middle. Luckily one of the outer sections came off in one piece so I could use that as a template to cut out the window gap. The centre piece I clamped in place and ran a pencil around the window gap from the outside. All marked up it was then just a case of using a jigsaw to cut out the holes. To help adhesion and avoid the glue of the fablon being dried out by the ply, I mixed up a solution of pva glue and water and gave each piece a generous covering.

To fix these back up I just used an electric nail gun with a good helping of 12mm pins . Once all up and fixed, I measured out rough sizes of fablon, stuck this to the wall and trimmed with a stanley knife.

Wall up, onto the window seal. Starting at the centre run the seal around the window, meeting back at the start + an inch. make sure its in full contact with the body and staple in place, its that easy. This video at about 4 minutes onwards shows very well how it should be done:

Now, he has a lovely window insert tool, I and probably you dont, so its a very manual job and time consuming. So much so I only managed to get one on before finishing up. But I'm happy to have made headway into the repair