Preparing Walls for Wallpaper: What to Check Before Anything Goes Up

Wallpaper is unforgiving in one specific way. It sits flat against the wall and reflects light evenly across a large surface, which means every ridge, hollow and patch underneath it becomes visible in a way it never was under paint. A wall that looked perfectly acceptable painted can look poor papered, and by then the paper is on.

Preparation is therefore not a formality. It is most of the job. Here is what to look at.

First, rule out damp

This is the one issue that stops everything else. Wallpaper adhesive needs a dry surface to bond to, and a wall with an active moisture problem will push the paper off, usually starting at a seam or a bottom corner. Worse, the paper traps moisture against the wall, so a damp patch that was drying slowly now cannot dry at all.

Look for the usual signs before you plan anything: a tide mark near the skirting, paint that bubbles or flakes in one area, a musty smell in a room that is otherwise clean, salt-like deposits on the plaster, or a patch that stays darker than the wall around it. On a coastal property, also check external walls on the weather side and any wall that backs onto a shower or a kitchen.

If you find damp, the cause needs fixing and the wall needs to dry out before papering. Papering over it is money spent twice.

Assess what is already on the wall

Existing wallpaper

Papering over old wallpaper is a false economy. The new adhesive re-wets the old paper, the old paper lifts, and both layers come away together. Old paper should come off, and the wall underneath should be washed down to remove residual adhesive, because dried old paste can prevent the new paste from bonding evenly.

Painted walls

Matt emulsion in good condition is generally the easiest surface to work with. Gloss, satin and any high sheen finish are the problem, because the surface is designed to repel things, which is exactly what adhesive does not want. Sheened walls need to be keyed back so the surface has some texture for the paste to grip.

Also check whether the existing paint is sound. Rub a hand across it. If it chalks off onto your palm, or if a strip of masking tape pressed on and pulled off lifts paint with it, the paint layer itself is not well bonded and the wallpaper will only be as secure as what it is stuck to.

New plaster

Fresh plaster needs to cure before it is papered. It is also highly absorbent when new, which means it can pull moisture out of the adhesive faster than the adhesive can bond. Newly plastered walls are usually sealed first so that absorbency is evened out.

Fix the surface itself

Once the wall is dry and clean, deal with the surface. Fill cracks and old fixing holes, and let filler dry fully before sanding it flush. Sand down any ridges, paint runs or previous filler that stands proud. Run your hand over the wall rather than only looking at it, because touch finds imperfections that a light-on wall hides.

Pay particular attention to areas around light switches, plug sockets and door frames, where previous work has often left a slightly raised edge. These are also the places where wallpaper is cut and where any unevenness shows most.

Hairline cracks that keep returning are worth investigating rather than filling repeatedly. A crack that reappears in the same place is usually movement, and it will eventually appear through the paper too.

Think about light before you think about pattern

A wall that receives raking light, meaning light hitting it at a shallow angle from a window or a downlight above it, will show surface imperfection far more than a wall lit face on. If the wall you are papering is the one beside a window rather than opposite it, the preparation standard needs to be higher, and a paper with some texture or pattern will be more forgiving than a flat, plain, pale one.

This is also worth weighing when choosing which wall to treat as the feature wall. The wall that looks most dramatic in a photograph is not always the one that will be kindest to a papered finish.

Practical things people forget

• Measure the whole wall including the awkward parts. Chimney breasts, reveals and returns all consume paper.
• Account for the pattern repeat. A large repeat means more waste, because each new drop has to be aligned to the last. The bigger the repeat, the more paper you need for the same wall.
• Buy the full quantity at once. Wallpaper is printed in batches and colour can shift slightly between batches. Running short halfway through a wall is a real problem.
• Keep a spare roll. Useful for a future repair, and from the same batch.
• Clear the room and lift what you can. Access to the full height of the wall matters more than people expect.
• Check that curtains, blinds or a pelmet are not going to sit over a seam you care about. Worth planning before installation rather than after.

Where a professional installation changes the calculation

Wallpaper hanging is a skill with a steep learning curve, and the parts that separate a good job from a poor one are mostly invisible until they go wrong: getting the first drop truly plumb, keeping paste off the face of the paper, matching a pattern across a corner that is not square, and cutting cleanly around a socket. A room papered by someone doing it for the first time often looks acceptable from the doorway and disappointing from a metre away.

Curtain Master supplies and professionally installs wallpaper, whether it is a single feature wall or a whole home, and stocks collections including Ambience, En Vogue, Octagon, Scott Living and Trilogy alongside ranges from Haus, Hertex, Silk House, U and G Fabrics and The Design Syndicate. Samples can be viewed at the Morningside and Springfield showrooms, which is worth doing, because paper looks different under your own light than it does on a screen.

If you want an assessment of a specific wall, you can browse the wallpaper ranges or request a quote and describe the room.