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What is a skim coat and what will it hide?

A skim coat is the thin finish on a wall or ceiling, and it follows the surface underneath rather than rebuilding a missing undercoat. This page does not print a thickness, so ask which plaster will be used, and leave a textured coating alone until you know what is in it.

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By the QuoteZila editorial team. Editorial policy.

What is a skim coat?

A skim coat is the last, thin layer of plaster. Its job is a smooth surface that can be painted or papered. It is not the layer that straightens a badly out-of-plumb wall, and it is not the layer that replaces plaster which has come away from the brick.

This page does not print a thickness for that coat. A number on one maker's sheet is that product's number, and another finish plaster can differ. When you compare quotes, ask for the product name and the thickness they will apply, not only the word "skim".

People posting from Cheshire, including Crewe, Nantwich and Sandbach, can use the same questions. Anyone in the UK can post a job or register a business. The questions do not change with the town.

Which backgrounds should the quote describe?

Ask the plasterer to name what they will skim onto:

  • New plasterboard, including whether the joints are already taped.
  • An existing finish that is sound but rough.
  • A backing coat that is still fresh, or one that has been dry for weeks.
  • A cement undercoat, which can keep moving as it dries.
  • A board sold for a bathroom or a kitchen.

Preparation is its own question. PVA, primer and bonding coats is about why a line that only says PVA is not a specification. This page stays with the finish coat.

What will a thin coat not do?

A thin finish follows dips, ridges and hollows. It will not fill a deep chase, rebuild a missing undercoat or bridge a crack that is still moving. Those jobs need a backing coat, new board, or a repair that is cut out and filled first.

Float plaster is the undercoat side of a two-coat system. Plastering repairs is for cracks and patches. The way a plasterer sets up a whole skim, including the room and the drying, is on how skimming is set up.

If a plasterer looks at the wall and says a skim is the wrong tool, that is useful information. Ask them what they would do instead, and ask the next plasterer the same question so the quotes describe the same work.

Ceilings, joints and decoration

On a ceiling, ask whether the quote includes the boards, the joints and the finish, or only the finish. A cracked joint and a ceiling that is sagging are not the same starting point. This page does not set out a taping method.

Decoration waits until the plasterer says the surface is ready. This page does not print a number of days, because drying depends on the room. Ask what to do with the windows and the heating, and do not hang heavy paper on plaster that still feels cold and damp.

Textured coatings and asbestos

Older ceilings and walls sometimes have a textured coating. HSE's diagrams of where asbestos can occur in buildings include textured decorative coatings on walls and ceilings, for example Artex [S1]. A pattern, a colour or the age of the house does not tell you whether asbestos is in it.

Leave the coating alone until you know. Do not sand it, scrape it or drill it to test a corner. A plasterer can talk about what they would do over a sound coating, or about testing before anything is disturbed. Health and Safety Executive (HSE). QuoteZila is not affiliated with this organisation.

HSE shows where asbestos can occur, including textured coatings, on its building diagrams.

If a large area of the inside of an outside wall is being re-plastered, building regulations can also apply. The Planning Portal says that where 25 per cent or more of an external wall is re-rendered, re-clad, re-plastered or re-lined internally, the regulations would normally apply and the thermal insulation would normally have to be improved [S2]. A small patch is a different case from a whole wall. Ask the plasterer and, if the area is large, ask building control.

Citizens Advice says to get written quotes from at least three traders, and that a quote is a fixed price while an estimate is a rough guess [S3]. For a skim, three quotes only help if each one names the same rooms and the same background.

Jobs you might post

These are examples, not taken from real job posts.

  • "Two bedrooms, plasterboard, joints untaped. Please quote to prepare the joints and skim. Name the finish plaster and the thickness."
  • "Living room walls were skimmed years ago and are sound but rough. Please quote a finish coat only if you agree the background is suitable."
  • "Textured ceiling, house built in the 1970s. Please do not sand it. Quote for advice on testing, and for a skim only if you are willing to do that over a coating that has been checked."

Getting skim quotes

Say which rooms, whether ceilings are included, and what is on the surface now. Up to five matched local businesses can send a quote [QZ2]. QuoteZila is free for customers and local businesses [QZ1].

Honest status: QuoteZila is new. We're starting in Cheshire, beginning with Crewe, Nantwich and Sandbach, and growing area by area. Anyone in the UK can still post a job or register a business. How fast you get quotes depends on how many local businesses have joined near you. Businesses can register and receive jobs straight away. We don't check insurance, qualifications or registrations, so please check these yourself before you hire.

Posting a job is not open yet

See our plasterers page. A wider look at what changes a plastering quote is on plasterer quotes.

Questions about skim coats

How thick is a skim coat?

This page does not print a thickness. A finish plaster's own sheet is the place that number lives, and two products need not share one figure. Ask which product your plasterer will use and what thickness they will apply. A coat described only as 'a skim' is not yet something you can compare.

Will a skim coat cover blown plaster?

A thin finish follows the wall underneath. It will not rebuild plaster that has come away from the brick, and it will not fill a deep hole. If the old plaster is loose, the job is an undercoat, a cut-out or new board. Ask the plasterer to say which, after they have seen it.

Can you skim moisture-resistant plasterboard?

This page does not print a maker's rule for that board. Ask the plasterer whether the board in your bathroom is one they will skim, and what they would do instead if they will not. The board itself is covered on the bathroom plasterboard page.

Could an old textured ceiling contain asbestos?

HSE lists textured decorative coatings on walls and ceilings, for example Artex, among the places asbestos can occur in a building. You cannot tell by looking. Do not sand, scrape or drill the coating. Ask for a test before any work that would disturb it.

Does QuoteZila check the plasterers who quote?

No. We don't check insurance, qualifications or registrations, so please check these yourself before you hire. You can report a quote or a business from your job page.

This page is general information, not professional or legal advice. QuoteZila does not check Gas Safe, WaterSafe, NFRC, NICEIC or other registrations against the register on your behalf: look them up yourself.

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Sources

  1. QZ1: QuoteZila product fact. QuoteZila home and FAQ copy.
  2. QZ2: QuoteZila product fact. QuoteZila FAQ How does getting quotes work.
  3. S1: Where asbestos can occur in buildings, HSE. Accessed 2026-10-28. https://www.hse.gov.uk/asbestos/diagrams.htm
  4. S2: Building regulations: external walls, Planning Portal. Accessed 2026-10-28. https://www.planningportal.co.uk/permission/common-projects/external-walls/building-regulations/
  5. S3: Before you get building work done, Citizens Advice. Accessed 2026-10-28. https://www.citizensadvice.org.uk/consumer/getting-home-improvements-done/before-you-get-building-work-done/