Preparing wall surfaces for Wallpapering
As with all other types of decorating, before wallpapering a wall it is important to spend time in preparation - time spent in properly preparing the wall will make it easier to achieve a good finish. It is false to think that as wallpaper covers the wall, you don't need to prepare the walls - poor wall condition will show through the paper.
Before starting to wallpaper, make sure that:
- The ceiling has been finished.
- Any coving, picture or dado rails has been fitted and finished.
- All other woodwork (door and window frames, architrave , skirting boards etc), has been finished by paint or varnishing.
In principle, all existing holes in the walls (including holes from small picture hook nails) should be filled during wall preparation, however, if it is intended that any fixing position will be reused (i.e. for brackets for shelves etc), these need not be filled and when you come to hanging the wallpaper, the positions can be indicated by using a matchstick to project from in each of the holes before the paper is hung and, once the strip has been hung, use the projecting matchstick to puncture the wallpaper - this will show the original position of the fixings.
The way the walls are prepared will depend upon the existing finish and the type of wall construction.
All existing wallpaper should always be removed as detailed on our 'wallpaper stripping' page. Pay special attention to ensure that all the residue from old adhesive is removed from the surface. People used to wallpaper on top of existing wallpaper but this never gives a very good finish.
Paint can be a real problem as so many different types were used is the past.
Check to find out if the paint is both non-water soluble and soundly bonded to the wall surface. In olden days, whitewash or distemper was often used as the decorative finish and these are unsuitable for wallpapering onto, pay special attention to areas around the tops of the walls; these areas may have been above a picture rail and this areas was often distempered.
To check if the paint is water soluble, dampen a clean sponge or cloth, then hold it against the surface of the paint for about 15 to 30 seconds. Then rub the area - if there is a large transfer of paint to the cloth/sponge, then the paint is water soluble and the it will need to be removed, if there is only a slight transfer of the paint colour to the cloth/sponge, then it should be all right to hang the wallpaper onto the paint surface.
To remove most water soluble paints requires plenty of cloth and water, and a lot of effort - it can be very messy, so old sheets or newspaper on the floor are advisable. Do not over soak the wall water as this can damage some plasters and the wall will need to dry out before it will be possible to hang your wallpaper.
If the paint is not water soluble, check to find out if the paint is soundly bonded to the wall - look for signs of paint flaking off.
Glossy and semi-gloss paint which is not flaking off should be lightly sanded to a dull surface to provide a key for the wallpaper paste.
Type of wall:
Little preparation is required for new plasterboard walls, however check to ensure that all the joints between the plasterboard pieces have been filled and allowed sufficient time for curing. Before hanging wallpaper, apply at least a couple of coats of dry wall primer - this seals the surface to a degree and will make subsequent removal of the wallpaper easier.
Check for, and repair any cracks, bumps or pits in the wall surface as described on our page for repairing plasterboard walls. Apply at least a couple of coats of dry wall primer.
Don't be in too much of a hurry to hang wallpaper on a newly plastered wall, the wall should be allowed time to dry out - a 4 week drying out period is typical but this will depend upon various factors, such as, the thickness of plaster and the humidity in the room - so ask the plasterer for his recommendation.
Check for any hollows or bumps in the walls, generally new plasterwork will be fine but it pays to check. Rub down any high points and fill in any dips.
The surface of the new plaster will need to be 'sized'. This is done either using brushing on 'size', or a dilute mix of wallpaper paste - most packets will give the details of mixing for 'sizing'. Ideally the 'size' should contain a fungicide (most do), this is particularly important when preparing a wall to hang vinyl wallpapers.
Check for, and repair any loose plaster and cracks etc as described on our page for repairing plaster.
Very old plaster can become very powdery over time (referred to as 'blown'),
- small areas lightly affected can be rectified by applying a coat of plaster sealer,
- if the wall is too bad in small areas, the damaged area can be racked out and replastered.
- where a whole wall (or large areas of it) is 'blown', it is more time/cost effective to strip off the old plaster and replaster
the whole wall.
Pay special attention to cracks in the plaster around the door and window frames and along the top of skirting boards; rake out any cracks and fill with a flexible decorator's sealant.
Finally the surface will need to be 'sized'. This is done either using brushing on 'size', or a dilute mix of wallpaper paste - most packets will give the details of mixing for 'sizing'. Ideally the 'size' should contain a fungicide (most do), this is particularly important when preparing a wall to hang vinyl wallpapers.
If there is any doubt about the wallpapering onto a particular surface, test it by pasting 3 small strips of wallpaper and fixing them to different areas of the wall then leave for about 3 days. Check to see if they are firmly attached; if they are, go ahead and wallpaper the wall, but if they come off fully the old surface finish, you need to do some more preparation.