I live in an attic, and the head part of my bed is in a corner where the roof slope, an outer wall and the wall to the neighbour's unheated attic meet. After a few winters of waking up to the feeling of the roof slope sucking the warmth out of me, I got a pack of polystyrol inner wall insulation. Unlike traditional styrofoam, it is a homogenous foam on the inside, similar to polyurethane foam. On the outside, it has a matte finish with a very fine paint-like structure.
I nailed the plates to the wall, right over the existing structured wallpaper. Then I filled the seams and the nail heads with acrylic caulk. Now I'd like to give it a finished look.
I feel adventurous enough to try a wallpaper. I have never applied wallpaper before, but it seems that the new cellulose-fleece-backed type is very easy to work with.
The problem is that the Internet tells me that regular wallpaper glue won't stick to regular styrofoam. I didn't find information specific to the glue for cellulose-backed wallpaper, or about this finished styrofoam. I also found the information that wallpaper can be applied to styrofoam in the following order:
- a layer of styrofoam glue, left to dry out
- a layer of underwallpaper soaked in normal wallpaper glue
- a layer of standard wallpaper, applied in the standard soak-in-glue method
This information came from the site of Henkel, manufacturers of styrofoam glue which costs 7 Euros per kg, an amount which only suffices for 1-2 square meters of wall.
Before I pay for glue two times as expensive as the styrofoam below it and three times as expensive as the wallpaper above it, I'd like to know:
- Is a base layer of styrofoam glue the only way to get wallpaper to hold to the styrofoam?
- Do I really need an underpaper layer if I am using a cellulose-fleece wallpaper as opposed to a standard one? Does it help hold the real wallpaper to the styrofoam, or is it just to give a nicer look?
- All articles I read agree that it is possible to paint over styrofoam using regular water-based inner wall paint. Could I paint over the styrofoam and apply wallpaper to the paint? It would cost three times less than the styrofoam glue.
This is what the caulked styrofoam looks like right now: