We are the owner of a modest pavilion, HLM construction (~ 1967), in good breeze block, and you in asbestos slate.
When I got there, I did some wall modification, tiling, electricity, paint and wallpaper.
Suffice to say that I did the cheapest, (often recuperated), and not the Promotelec standard of the year.
There was improvement.
I always have wooden windows, which I patch up and it's going well.
There is a second interior window on the woodwork, made by a company before my purchase. This is called SURVITRAGE.
Solution that saves 2 degrees, for no big cost (€). This can be done, by a handyman (no more difficult than doing picture framing).
On all the walls, which overlook the facades, I glued a 6mm DEPRON sheet, with special glue. Galley for the wallpaper above. So it is imperative to paint a coat of grip paint. Not glycero which melts polystyrene. No vinyl like I did, which peels off with wallpaper glue. We gain another degree.
In the attic layer of glass wool on the ceiling.
And that's all.
The best to come, would be insulation from the outside and redo the roof, putting insulation between rafters and laths under non-asbestos slate.
Problematic authorization, because insulation on a facade on public roads, and for the roof, semi-detached semi-detached pavilion.
And then, if it is only to gain more degrees ... I would have to sell them to the neighbors ...
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If not on your previous questions: you do Google
"extra glazing", and you find all you need as solutions / Batiweb, Maison-brico ...
