Hiring a professional wallpaper hanger is usually a worthwhile idea because, while the application of wallpaper itself is easy, getting the finished product to look good is complicated and takes a lot of practice and patience. A professional wallpaper hanger will not only be able to hang your wallpaper seamlessly, but they will also get an even application of wallpaper paste to avoid bubbling and imperfections immediately and over time. Plus, they can provide their professional opinion on whether to remove or wallpaper over an existing layer of wallpaper.

You may end up with extra wallpaper once your project is finished. Hang on to that wallpaper, as you may need to use it to patch up areas that get damaged later on. If you have a lot of excess wallpaper, try getting creative with it. You can use it to line the inside of a cabinet or drawers, for example.

If you can already see the texture of the existing wallpaper through the layer of paint, then the texture could also come through the new layer of wallpaper. If that’s the aesthetic you want, then proceed. But if you want a smoother surface, you should either strip off the existing paint and wallpaper or hang a layer of liner paper before proceeding.

Yes, many types of peel-and-stick wallpaper can be used in bathrooms, especially those made of vinyl or polyester. However, its success depends heavily on the level of moisture and ventilation. In bathrooms with good ventilation, such as those with fans, it can be a durable option. Peel-and-stick wallpaper may not adhere as well as traditional wallpaper in very humid conditions. For bathrooms that see a lot of moisture, like a kids' bathroom or a full bath with a steamy shower and poor ventilation, even high-quality peel-and-stick wallpaper is likely to peel over time.