While it's usually better to remove your paper before painting, there are some cases where painting over wallpaper may actually be beneficial. First, and most importantly, the drywall or plaster walls under the paper will remain intact. Removing old paper, or many layers of paper, often causes unexpected damage to walls. By leaving the paper in place, your walls will stay in their current condition. Second, leaving the paper in place will allow you to paint your walls much more easily and quickly. Removing paper is difficult and time-consuming, so many people are eager to skip this task.
If you decide that you're going to go ahead and paint over your wallpaper, it's important to prep your walls carefully to ensure the best results possible. Start by securing the paper. Remove and replace damaged sections and add adhesive to loose pieces to minimize the chance the paper will fall. Add a thin line of clear caulk around the perimeter of the walls, at the joint seam where the paper meets the floor and ceiling. This will help seal the edges and keep the paper from peeling after you've painted [source: Schunck].
Next, prep your walls carefully. Cover heavily textured paper with a thin coat of joint compound (spackle). This material will help smooth out the surface so that the texture won't show through the paint. Gently sand down the seams of the wallpaper so they're not as noticeable. Apply a coat of oil-based primer to the entire surface of the walls before painting. This helps seal the adhesive in the paper away from the moisture in the paint. Moisture from paint can often loosen wallpaper glue, causing bubbles or peeling. In addition to applying a primer, try to use oil-based paints to minimize the impacts of moisture of adhesives [source: Heavens].
Now you're ready to make a decision about your walls. But before you do, read some of the information on the next page. It may help you with this decision or some others that may come up in your renovation project.