Sticking thermal insulation foam
It is also a backing material, which is placed on the glued wall. It can be glued with both vertical strips, and horizontal (the first way is easier). Remember when planning your work, that the joints of the backing wallpaper cannot coincide with the joints of the decorative sheets. The foam easily crumbles and breaks, so you have to be very careful.
Spread strong wallpaper glue with a brush on a section of the wall equal to the width of one sheet and let it dry. Place the top edge of the roller against the ceiling and unfold the roller on the wall, making sure that the side edge coincides with the previously drawn guide line. Smooth the surface with a wallpaper brush or roller. Be especially careful when trimming the bottom edge of the sheet, due to the fragility of the material. Press it gently against the skirting board and cut along the drawn line.
Only then press the polystyrene against the wall.
Connect the next sheets with one another, pressing the edges with a roller against the joints.
Gently press the foam against the baseboard, mark the cut line and cut with scissors or a knife.