It's both plaster and tretex and in some places mixed.
We are now applying 13 mm gypsum on all the tretex where we can easily reach (e.g., not the stairs) and priming and applying restorers on plaster. In places where plaster and tretex are mixed (around the chimney), gypsum will be glued to the chimney and screwed into the tretex.
13 mm gypsum costs about 22 SEK/sqm plus filler. Restorers are approximately 40 SEK/sqm plus adhesive. I don't think we'll apply microlit on the gypsumed walls since the large walls will be wallpapered and the painted ones have many doors and windows, so joints will not be visible anyway. There is quite a bit of work with filler, but some filling will be needed even with restorers, so the hardest part is probably carrying the gypsum, I think..
/pikachu
