Can I apply wallpaper directly onto ingrain wallpaper?

Gluing wallpaper onto existing ingrain wallpaper is not recommended. The structure of the ingrain wallpaper would be pressed through the new wallpaper, and there may also be difficulties with the adhesion of the new wallpaper to the substrate. We therefore generally recommend that you first prepare a dry, smooth, clean and evenly absorbent substrate.

>> For more information, read "How do I prepare a wall or ceiling for wallpapering?"