How would you have insulated and built the sides around the window that is in the picture? It can protrude about 4 cm from the wall, but maybe that's barely helpful with such little insulation.
3 cm cellplast plus 1 cm plywood/drywall? Or do you have any other smart tips, I would be grateful
We had exactly the same "challenge" when we renovated and replaced windows.
We smeared plaster on the wall and pressed a gypsum board there. So, we used the plaster as "glue". The advantage of the plaster was that it was also easy to fill in the irregularities in the plaster behind, which I see you also have! I reasoned that the little insulation that you can add there hardly makes a noticeable difference!
Then on the outer corner, towards the room, I applied a fiberglass tape to avoid cracks. In our case, we then used plaster both in the window recess and on the walls, so it became a single entity!
SPU plaster can become too dense...the advantage of plaster mortar with reinforcement is that it works well with the substrate, and the difficulty is applying it evenly and neatly...but if you do as the pictures above show and press a plasterboard into the plaster mortar, then it should be good, right?
