I own an older house (early 1900s), and It has as much as 5 layers of wall paper on the walls and the ceiling. There is about 1000sq. ft. of floor space, so I would like to avoid scraping all of the paper off. Also, the wallpaper has been painted over with several coats of paint, which makes it even more difficult to scrape. Lines from the overlaping wall paper are visible as well as some small cracks in the plaster. Could I lay drywall over the wallpaper and plaster, or is my only option to remove the wall paper?