How to Fix Gaps and Lifting at Wallpaper Seams
Telling a gap from a lift, closing each one properly, and the two habits that stop it happening on the next wall
A thin line opening between two lengths is almost always shrinkage. The paper was stretched slightly while it was smoothed, and it has pulled back as it dried. A lifted or curling edge is almost always a dry strip of wall where the paste did not quite reach. Both are fixable; the second is easier.
This is the single most common wallpapering complaint, and the one most often blamed on the paper when the cause is the hanging or the room.
Which problem do you have?
- A gap: the two edges are flat to the wall but no longer touching, showing a line of wall between them.
- A lift: the edges are still the right distance apart but one or both have curled away from the wall.
Fixing a hairline gap
- Dampen both edges very slightly with a clean, barely damp white cloth to relax the paper.
- Ease the two edges together with your fingertips.
- Run a seam roller gently down the join.
- Wipe any moisture off the surface straight away.
Fixing a wider gap
- Lift each edge slightly with a filling knife.
- Work a small amount of adhesive underneath with a fine brush.
- Push both edges towards each other, then roll gently.
- Hold for a moment. Do not tape it.
Beyond a millimetre or two, no amount of coaxing closes a gap, and the length needs replacing. That is the argument for the spare roll, and for ordering it with the original order rather than later.
Fixing a lifted or curling edge
- Lift the edge gently, enough to see behind it, not enough to crease it.
- Slide a fine brush in and apply a little adhesive to the wall behind, not to the paper.
- Press the edge back and roll it gently with a seam roller.
- Wipe off any adhesive that comes out at the join, immediately, with a clean slightly damp white cloth.
If the same edge lifts again after a week, the problem is behind the paper: dust, a dry patch, or moisture in the wall.
Why seams open
- The paper was stretched. Scrubbing at a length with a smoother pulls it a millimetre or two wider, and it recovers as it dries. Firm, even strokes, not pressure.
- The room dried too fast. Heating turned up, or windows open. The surface dries before the paste behind has gripped, and the paper contracts against a bond that has not formed.
- The room was too cold. Paste takes much longer to grab in a cold room, and the paper can move before it does.
- Dry paste at the edges. Pasting only the width of the length leaves nothing where the join lands.
- Overworking the seam roller, which squeezes adhesive out from under the edges.
Preventing it on the next wall
- Paste wider than the length. About 60cm for a 48cm width, and right into the corners.
- Smooth, don't scrub. Steady overlapping strokes from the centre out.
- Keep the room at an ordinary, steady temperature while it dries, windows closed, heating as normal, for 24 to 48 hours.
- Roll seams once, gently.
- On dark colourways, paint a stripe first. A narrow band of close-matching matt emulsion down the wall where each seam will fall means any movement shows a dark line instead of a white one. It costs nothing and it is what a decorator would do.
Why are my wallpaper seams gaping?
Usually the paper was stretched while being smoothed, or the wall dried too quickly, so the length shrank back away from its neighbour.
Can I fix a gap after the paper has dried?
A hairline gap, yes: dampen, ease together, roll. Anything wider than a millimetre or two needs the length replacing.
Why is the edge of my wallpaper lifting?
Almost always because the paste did not reach the very edge of the length.
Should I overlap the seams to avoid this?
No. An overlap leaves a permanent ridge. Our papers are butt-join.
Is a gap at the seam a fault in the paper?
Very rarely. Non-woven paper does not expand or shrink appreciably on its own. The movement comes from how it was hung and how the room dried.
What temperature should the room be?
Ordinary room temperature, steady, with no draughts and no direct heat on the wall.
