Skim coat going on over old plaster, London

Skimming

Skimming in London

A thin finish coat that takes a wall or ceiling back to flat, without stripping the room out first.

Written price after a look at the job

Dust sheeted, swept and cleared down daily

One person on site, start to finish

Work planned around parking and access

Skimming is the job most London rooms actually need. The walls are solid enough, but the surface has had thirty years of filler, wallpaper, patched sockets and a chimney breast taken out, and no amount of painting will make that read flat again.

A skim is two thin coats of finish plaster over what is already there. It is quicker, cheaper and far less disruptive than taking the room back to brick, and on a wall that is sound it gives exactly the same finished surface.

Whether your walls will take a skim

The test is whether the existing plaster is stuck to the wall. Tapping across it tells you most of what you need to know: a solid dull note is fine, a hollow drummy one means the plaster has let go of the brick behind it and is being held up by the paint.

Small hollow patches get cut out and made good first. If most of a wall rings hollow, skimming it is throwing money at it, because the new surface is only as attached as the old one under it. That gets said before the job is priced, not after the sheets are down.

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Preparation, which is most of the work

Wallpaper comes off. All of it, including the backing paper people leave on, because plaster laid over paper pulls it off the wall as it shrinks. Old flaking paint gets scraped back, and anything shiny gets a coat of bonding agent so the skim has something to grip.

Suction is the other half. A dry, thirsty old wall pulls the water out of the plaster before it can be trowelled, and you end up with a surface full of drag marks and crazing. Controlling that with a primer or by damping down is the difference between a flat wall and a rough one.

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Ceilings, artex and overboarding

Ceilings are harder than walls and they show more, because light crosses them at a low angle and picks up every ripple. A sound ceiling can be skimmed directly. A textured one is usually better overboarded, with new board screwed up through the old surface into the joists, then skimmed.

Overboarding also settles the artex question without disturbing it. Textured coatings applied before the mid eighties can contain asbestos, and the safe way to deal with those is to leave them alone and cover them, not to scrape, sand or steam them off.

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What a finished skim should look like

Flat, closed and even. Run a hand across it and there should be no ridges at the trowel joins, no hollows where a socket was filled, and no soft edges at the angles. Hold a light along the wall and the reflection should travel evenly instead of breaking up.

It should not need filling before it is painted. If a decorator has to go over a new skim with filler and a sanding block, the skim was not finished. That is the standard the price is based on.

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When to get it looked at

Walls that look flat until the light comes across them
Rooms stripped of wallpaper and left in a state underneath
Artexed or textured ceilings you want gone
Patch repairs that read through every coat of paint
New plasterboard that needs a finish rather than tape and joint
A whole flat being redecorated before it goes on the market

Skimming on site

Photographs of finished work go here. Until they do, each frame is labelled with what belongs in it rather than filled with a picture of somebody else's job.

Skimming across London

Central and South West London

Skimming: frequently asked questions

How much mess does skimming make?

Less than a full replaster, but it is still wet work. Floors get sheeted, and there is scraping and sanding at the preparation stage which makes dust. The room wants to be empty, or everything in it covered and moved to the middle.

Can you skim over wallpaper?

No. It looks fine for a week and then the plaster shrinks as it dries, pulls the paper off the wall and takes the new surface with it. The paper comes off first, backing included.

Will skimming fix a damp wall?

No. Plaster laid over a damp wall will stain, blow and come away, because the water is still arriving from somewhere. The leak, the failed pointing or the bridged damp course has to be dealt with first, and the wall has to dry.

Is skimming cheaper than replastering?

Usually, because there is no hacking off, no waste to carry out and less material going on. The saving only holds if the existing plaster is sound. Skimming a wall that is already letting go costs the whole job twice.