In most cases, it is not recommended to wallpaper over existing wallpaper, as the success depends on the type of paper already on the wall. While you might be able to cover non-coated wallpaper, you should never apply new wallpaper over a vinyl-coated one, which is more common. Doing so can lead to poor adhesion, resulting in bubbles, imperfections, and peeling. It can also trap moisture, potentially causing hazardous mold growth between the layers.

Even if the existing wallpaper is suitable, experts recommend applying only one new layer. Adding multiple layers (more than two total) can cause significant adhesion problems, leading to warping and bubbling. For the best results, the recommended approach is to remove the old wallpaper and all paste residue before hanging the new paper. If you are unsure about your wallpaper type, consider consulting a professional.

While peel-and-stick wallpapers require no time to cure, the adhesives for other types of papers will take a day or two to dry and up to three weeks to fully cure. The differences are the type of paper, the type of adhesive, and the humidity and temperature in the space. 

If you prefer peel-and-stick to traditional wallpaper, you can skip the priming process. Many manufacturers don't require an additional primer if you’re installing peel-and-stick wallpaper to painted walls. However, if you’re applying peel-and-stick wallpaper to unfinished drywall, you’ll need to apply a primer first.

Yes, but professional services ensure secure installation, accurate leveling, and protection against wall damage, especially for heavy or valuable items.