If you do not have the time or the funds to strip your wallpaper the following is for you. Depending on the quality of the wall papering job to begin with, will determine whether one can paint the paper or not. If the wall paper is completely tight on the wall and in the corners, where it meets the ceiling and the skirting boards, then there should not be a problem, the paper may bubble up after painting, but it will pull back when it dries, if this happens it is advisable only to paint one coat in a day, this way the paper stays on the wall. You may have to fill the seems on the paper depending again on how well it was hung.
It may take a couple of coats to cover any patterned paper, more so than painting over any solid colour. If the paper is a vinyl paper a special primer or undercoat may be used, Also with vinyl papers that appear smooth, but have variations in the pattern, then the pattern may still be seen when viewed against the light. Stripping paper is generally a better option, but sometimes painting over it is. If it is an old house, the walls may be in very bad condition under the wall paper; it may be a much cheeper option to paint over the paper and far less time consuming as the paper on the wall acts as a lining paper. In Other cases where there are new builds, the builder offered a “special deal” and you could get a great price on wallpaper. But in many cases (not all) this gave the builder the opportunity of not finishing the walls correctly and just papering over the plaster board. Now when it comes to stripping this off a wall that has not been plastered or sealed, you can run into real problems, and again it may be a better option to leave the paper and paint over it.
So there you have it, if you are not sure ask a professional, and they can guide you as to the best approach to take with your painting and decorating, wall paper stripping, and indeed wallpaper hanging, and of course whether to paint over the wallpaper or not.