Whether you can apply wallpaper over a textured wall depends on the texture type. Wallpaper works best on smooth, flat surfaces, so even if the wallpaper sticks on your textured wall, the texture is likely to show through, and it may even wrinkle or damage the paper. You’re more likely to get good results with shallow textures like orange peel and knockdown than with rougher textures such as popcorn and slap brush. Test a small section before going all-in and wasting your wallpaper.