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What is float plaster and when is it used?
Floating is the undercoat that brings a wall towards a flat plane before a thin finish goes on, and the finish is a separate coat. This page does not print a thickness for either coat, and overhead work stays with the plasterer rather than a job to start from a chair.
Last reviewed:What does floating a wall mean?
When a plasterer says they will float and set a wall, they mean two coats. The float is the undercoat that builds the wall out towards a flat plane. The set is the thin finish that makes it smooth enough to decorate. People also call the undercoat a backing coat or a scratch coat.
This page is only about that undercoat. What a skim coat is covers the finish. How a skim is set up covers the room, the drying and what to ask. A line that only says PVA is a third question: PVA before plaster.
This page does not print a thickness, a temperature limit or a list of backgrounds for a named bag. Those figures belong on the sheet for the product the plasterer will actually use. If the quote says "float" and nothing else, ask what is in the bag and what depth they intend.
A house in Cheshire is described the same way as a house anywhere else: the background decides the coat. Crewe, Nantwich and Sandbach are among the first towns on QuoteZila, and anyone in the UK can post a job or register.
What should the quote split out?
Ask for two lines even if one price covers both:
- The undercoat: product name, and the thickness they intend.
- The background: brick, block, old plaster hacked off, or something else, and whether it is dry.
- The finish coat: included or not, and the product name.
- Ceilings: in the same system, or a different one, or not in the job.
- Access, especially on a landing or a stair flight.
Citizens Advice says to get written quotes from at least three traders. A quote is a fixed price. An estimate is a rough guess [S2]. After you accept a quote it is a binding agreement, so the undercoat and the finish have to be in the writing [S2].
A quote that only says "float and set" hides which product, which thickness and whether ceilings are in the same system.
What should you say about a wet wall or a bathroom?
Before anyone prices the undercoat, the useful facts are whether the wall is dry, whether it is new block that still holds water, and whether the room stays wet. A green background, in plastering talk, often means masonry that has not dried. Say what you can see. You are not expected to diagnose it.
A bathroom that stays wet may be a poor place for an ordinary gypsum undercoat. Board choice in a bathroom is covered on bathroom plasterboard. Ask the plasterer what they would use there, and do not assume the hall plaster is the bathroom plaster.
Where 25 per cent or more of an external wall is re-plastered internally, the Planning Portal says the regulations would normally apply and the thermal insulation would normally have to be improved [S3]. A single chimney breast is not automatically that case. A whole outside wall, replastered on the inside, might be. Mention the size.
Why is a ceiling a different access question?
A ceiling undercoat is slower than a wall, and a fall from a hop-up or a stairwell is work at height when, if precautions were not taken, a person could fall a distance liable to cause injury [S1]. HSE's definition includes work above ground or floor level [S1]. A slip on the level is not work at height [S1].
This page does not tell you to float a ceiling yourself. Ask the plasterer what they will stand on, and keep the stair flight clear. HSE: work at height. QuoteZila is not affiliated with this organisation.
The HSE definition is on its work at height questions.
Jobs you might post
These are examples, not taken from real job posts.
- "Chimney breast hacked back to brick. Please quote to float and set. Name the undercoat, the thickness and the finish plaster."
- "Block wall in an extension, still drying. Please say whether it is ready, and what you would use."
- "Ceiling is lath and plaster and sagging. Please quote to overboard or to float, and say which, with the access you need."
Comparing float quotes
Photos of the bare background help more than a room name. 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. What changes the wider plastering quote is on plasterer quotes.
Questions about float plaster
What do plasterers mean by floating?
Floating is the undercoat stage. The plaster is applied and ruled towards a flat plane so a finish coat can go on afterwards. Setting, or skimming, is the thin coat. This page is about the undercoat. The finish is covered separately, and this page does not print a thickness for either coat.
How thick is a gypsum undercoat?
This page does not print a thickness. One bagged undercoat and a sand-and-cement float are different specifications, and a ceiling need not use the same depth as a wall. Ask your plasterer which undercoat they will use and what thickness they intend on the background they have seen.
Can this undercoat go on any wall?
Not every background wants the same coat. A dry dusty brick wall, a new block wall that is still wet, and a smooth dense block are different jobs. Ask the plasterer to name the background and to say if it is ready. This page does not print a list of banned backgrounds for a named bag.
Can you decorate straight onto the undercoat?
Ask the plasterer. Many undercoats are not a surface you paint or tile onto, and the quote should say whether a finish coat is included before decoration. If the quote only says 'float', ask whether the finish is in the same price.
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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Related pages
- Hardwall Plastering: What It Is and When It Is Used. What hardwall plaster is, when a plasterer uses it as a backing coat on brick or block, how it differs from other plasters, and what to ask before work starts.
- Insulating Render: What It Is and When It Fits. What insulating render is, how it differs from an insulation board system, where it suits an older wall, and the permission questions to ask before work.
Sources
- QZ1: QuoteZila product fact. QuoteZila home and FAQ copy.
- QZ2: QuoteZila product fact. QuoteZila FAQ How does getting quotes work.
- S1: Work at height: frequently asked questions, HSE. Accessed 2026-10-28. https://www.hse.gov.uk/work-at-height/faqs.htm
- S2: 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/
- S3: Building regulations: external walls, Planning Portal. Accessed 2026-10-28. https://www.planningportal.co.uk/permission/common-projects/external-walls/building-regulations/