Although hanging wallpaper is not a very difficult project, removing it from the wall can be an entirely different matter. Most experts recommend removing the old wallpaper, particularly if there is more than one layer of wallpaper already on the wall. It is, however, possible to place new wallpaper over old wallpaper. The key to this project is to properly prepare the surface prior to hanging the new paper.
Inspect the old wallpaper. Check for any tears, bubbles or lumps. Check to see how many layers of wallpaper are on the wall. If there is more than one layer of wallpaper, you should remove the old ones before hanging the new paper.
Reattach any loose seams by placing seam sealer on the backside of the wallpaper and rolling over it with a paint roller.
Use a putty knife to spackle over any uneven areas and holes. Spackle over overlapping seams and nicks and in the wall. Allow the spackle to dry.
Gently sand over any spackled areas until the wall is smooth to the touch.
Wash the wall with ammonia and water. Allow time for the wallpaper to dry.
Remove a piece of the old wallpaper with a putty knife. Dampen the piece with water and wipe it with a sponge. If ink comes off on the sponge, you must seal the old wallpaper.
Roll on a layer of primer-sealer if ink appeared on the sponge. The ink indicated the old wallpaper is porous and will run through the new paper. Roll on a layer of vinyl-to-vinyl primer if the wallpaper is vinyl and the ink did not appear on the sponge. The vinyl-to-vinyl primer will also help the new wallpaper stick to the wall.
Allow the primer to dry. Paste and place the new wallpaper over the old one. Roll the seams and any bubbles with a paint roller.
Things You'll Need
The primers are available at home improvement and most paints stores. If you are not sure what's the best primer, show a sample of the old wallpaper to an expert.
Do not use too much force when applying seam sealer with the paint roller. Pressing too hard will force the sealer through the seams.