We are renovating surfaces in our house built in 1934 and have torn off thick layers of old wallpaper, several layers of filler, and silicone joints. Behind it, there are masonite boards that are not smooth but seem to be set with the back/fiber side outwards (?). How should we make the walls smooth? Renovation wallpaper on the masonite? Remove the masonite and install drywall? Renovation drywall?
What is behind the masonite? I would probably have taken down the masonite and filled with gypsum mortar followed by regular filler, or alternatively glued regular gypsum with gypsum mortar. Renovation gypsum is quite difficult to glue because it is so flimsy, in my experience.