Drying · checked 29 October 2026
Screed drying time
How long each kind of screed takes to dry, how dry it has to be, and how to bring the date forward.
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- Sources under every figure
Figures checked against each source on 29 October 2026. How we check
Screed dries at roughly a millimetre a day for the first few centimetres, then more slowly. BS 8204-1 allows one day per mm for the first 50 mm of a sand and cement screed, so 50 mm takes about two months in good conditions.
Roadstone and Gyvlon give one day per mm for the first 40 mm of their liquid screeds and two days per mm after that. Most floor finishes need the screed at 75% relative humidity or below, so it's tested, not guessed.
Screed planner
Plan your screed
Put in your floor and the day it's laid. You get the volume, the weight, when it should be dry enough for floor finishes, and when the heating can go on, from the makers' own figures.
Drying times are for good conditions, closed up and ventilated. The floor is tested before finishes go down, not guessed. None of the Irish screeding contractors' sites we checked publish a price per m², so the price comes from your floor.
The rules of thumb
| Screed | Rule | Source |
|---|---|---|
| Sand and cement | 1 day per mm for the first 50 mm; 2 days per mm from 50 to 75 mm is generally accepted | BS 8204-1, cited by Ronacrete |
| Cement liquid (Roadstone FlowPlus) | 1 day per mm for the first 40 mm, then 2 days per mm | Roadstone |
| Calcium sulphate (Gyvlon) | 1 mm a day up to 40 mm, then 0.5 mm a day | Gyvlon |
| Fast-drying (Mapei Topcem) | Ready in about 4 days | Mapei |
Sources: Ronacrete, Drying of Screeds; Roadstone FlowPlus cement liquid screed brochure (RS.BRO-19 Rev 01, March 2022); Gyvlon flowing screed general data pack (Anhydritec); Mapei Topcem technical data sheet. Checked 29 October 2026.
Days by thickness
| Thickness | Sand and cement (BS 8204-1 rule) | Roadstone FlowPlus rule | Gyvlon rule |
|---|---|---|---|
| 35 mm | 35 days | 35 days | 35 days |
| 40 mm | 40 days | 40 days | 40 days |
| 50 mm | 50 days | 60 days | 60 days |
| 65 mm | 80 days | 90 days | 90 days |
| 75 mm | 100 days | 110 days | 110 days |
Our arithmetic from the rules above, for good drying conditions. Ronacrete's own figure for 75 mm of sand and cement with no additive is about 100 days.
Walk on it is not the same as dry
| Screed | Walk on it | Floor finish |
|---|---|---|
| Calcium sulphate (Gyvlon) | 24–48 hours | When tested at 75% RH (0.5%), after sanding and priming |
| Cement liquid (FlowPlus, Cemfloor) | 24–48 hours | When tested below 75% RH, after the heating cycle if there's underfloor heating |
| Fast-drying (Topcem) | 12 hours | Tiles 1 day, stone 2 days, wood and resilient 4 days |
| Sand and cement | 7 days (Gyvlon's comparison); cured under polythene at least 5 days (MPA) | When tested at 75% RH |
Sources: Gyvlon flowing screed general data pack (Anhydritec); Roadstone FlowPlus cement liquid screed brochure (RS.BRO-19 Rev 01, March 2022); Cemfloor Complete technical data sheet (2023); Mapei Topcem technical data sheet; Mineral Products Association, Mortar Data Sheet 22: Screeds (Issue 3, October 2023). Checked 29 October 2026.
How dry is dry: the 75% RH test
Ronacrete lists 75% surface relative humidity as the limit for resilient flooring, carpet, quarry tiles, ceramic tiles and stone. BS 8201:2011 refers to 75% for wood flooring, but many wood flooring suppliers say that applies only to floating floors and ask for lower figures for bonded wood. Check the flooring maker's own figure.
Roadstone asks for less than 75% RH, about 2% by the carbide method, before wood or vinyl goes on FlowPlus. Gyvlon asks for 75% RH, or 0.5% moisture, on calcium sulphate, tested by hygrometer, carbide test or oven test.
Sources: Ronacrete, Drying of Screeds; Roadstone FlowPlus cement liquid screed brochure (RS.BRO-19 Rev 01, March 2022); Gyvlon flowing screed general data pack (Anhydritec). Checked 29 October 2026.
What slows drying, and what speeds it up
- Cold and damp air slow it. Lower temperature, higher humidity, a thicker screed and a leaner mix all add time, Ronacrete says.
- Protect first, then ventilate. Roadstone keeps FlowPlus closed up for 7 days, then opens windows and doors from time to time. Gyvlon protects its screed for 48–72 hours, then wants the building warm and ventilated.
- Dehumidifiers. Gyvlon allows them from 72 hours on calcium sulphate, in a closed room with the water emptied regularly.
- Underfloor heating. Gyvlon allows force drying from 7 days; Roadstone commissions FlowPlus heating from 14 days at no more than 45°C.
- No gas heaters. Gyvlon says fossil-fuel heaters must be avoided because they raise the humidity.
- Thinner screed. 30 mm less screed is at least 30 days less drying, at 1 mm a day or slower.
Sources: Ronacrete, Drying of Screeds; Roadstone FlowPlus cement liquid screed brochure (RS.BRO-19 Rev 01, March 2022); Gyvlon flowing screed general data pack (Anhydritec). Checked 29 October 2026.
If the dates can't move, plan a fast-drying screed from the start.
Questions people ask
How long does screed take to dry?
About one day per mm for the first 50 mm of sand and cement (BS 8204-1), so two months for 50 mm. Liquid screeds: one day per mm for the first 40 mm, then two days per mm (Roadstone, Gyvlon).
How long does 75 mm of screed take to dry?
Ronacrete puts a 75 mm sand and cement screed with no additive at about 100 days to reach 75% RH in good conditions.
When can I walk on new screed?
Liquid screeds: 24 to 48 hours (Roadstone, Cemfloor, Gyvlon). Mapei Topcem: 12 hours. Sand and cement should be cured under polythene for at least 5 days (MPA).
Can I use the underfloor heating to dry screed?
Yes, on the maker's schedule. Gyvlon allows it from 7 days; Roadstone from 14 days at no more than 45°C.
What moisture level does screed need before flooring?
75% relative humidity or below for most finishes (Ronacrete). Gyvlon gives 0.5% moisture for calcium sulphate; Roadstone about 2% by carbide for FlowPlus.
Sources (6)
Prices and facts on this page were checked against these published pages. We are not connected to these businesses.
- Ronacrete, Drying of Screeds: ronacrete.co.uk
- Roadstone FlowPlus cement liquid screed brochure: roadstone.ie
- Gyvlon flowing screed general data pack (Anhydritec): specifiedby.com
- Mapei Topcem technical data sheet: cdn.shopify.com
- Cemfloor Complete technical data sheet: cdn.shopify.com
- Mineral Products Association, Mortar Data Sheet 22: Screeds: mortar.org.uk
Get your floor priced
Four taps about the job and one screeding contractor who covers your county rings you. Or call 087 162 1846, lines open 8am to 8pm.