Screed Types Compared: Which One Is Right for Your Project?

In brief: There are three main screed types used in UK flooring projects – calcium sulphate (anhydrite) liquid screed, cement based liquid screed, and traditional sand and cement screed. Each can be installed as a bonded, unbonded or floating screed depending on the substrate. Calcium sulphate is usually quick to become walkable and performs well around underfloor heating, but can’t be used in wet areas. Cement based screed is also pumped and self-levelling but with better moisture resistance, so it’s also suitable for bathrooms and wet rooms, and dries at a similar rate to calcium sulphate or even faster, depending on the specific product. Traditional sand and cement screed is the most affordable option, and it’s practical for sloped or wet room floors, although it takes the longest to dry and is also more labour-intensive to install.

At a glance

Screed type	Best for	Typical thickness	Key advantages	Key considerations
Calcium sulphate (anhydrite) liquid screed e.g. Gyvlon	Underfloor heating, larger open areas, projects needing a fast turnaround	Usually 30 to 75mm. Bonded applications are less common but figures range from around 15mm (specialist products) to 25mm (standard products)	Quickly walkable, flows around UFH pipework with minimal voids, low shrinkage and low risk of cracking, can be laid thinner which helps heat transfer	Not suitable for wet areas as it’s water soluble, shouldn’t be laid with metal mesh reinforcement, needs the surface sanded to remove laitance before flooring
Cement based liquid screed e.g. Cemfloor	Wet rooms, bathrooms and areas with moisture exposure that still need a pumped, self-levelling finish	25 to 75mm depending on installation method and exact product	Same fast, self-levelling pumped application as calcium sulphate but better moisture resistance and often faster drying. Also works well over underfloor heating	Still a specialist pumped product so needs the right installer, drying speed varies by manufacturer but is often faster than calcium sulphate
Traditional sand and cement screed	Sloped floors and wet rooms where liquid screed can’t be used, budget sensitive projects	Usually 50 to 75mm, and generally can’t be laid much thinner than that without compromising strength	Lowest material cost, well understood and widely available, can be mixed and laid by hand if needed	Takes a lot longer to dry, especially at greater thickness, is more prone to voids around UFH pipes and cracking if not laid well, more labour-intensive

Calcium sulphate (anhydrite) liquid screed

Pumped into place and self-compacting, this is the screed of choice when speed and a clean finish around underfloor heating pipework matter most. Calcium sulphate screeds, like Gyvlon for example, shrink very little as they cure, which keeps cracking risk low, and they’re usually able to take foot traffic within 24 to 48 hours under good drying conditions. The trade-off is that it’s water soluble so it’s not suitable for use in bathrooms, wet rooms or anywhere with sustained moisture exposure, and the surface needs sanding to remove the laitance (crumbly layer that forms as the screed dries) before tiles or other coverings go down. Calcium sulphate screeds also shouldn’t be laid with metal mesh reinforcement, since the material can cause the metal to corrode.

Cemfloor screed being dappled by Somerset Screed — Image courtesy of Somerset Screed Ltd.

Cement based liquid screed

Cementitious liquid screeds like Cemfloor or Tarmac Topflow C give you the same pumped, self-levelling installation as calcium sulphate, but with a cement binder instead of gypsum. That single difference opens up wet areas that calcium sulphate can’t go near, while still keeping the speed and flat finish of a liquid screed. The drying speed of cement-based liquid screeds depends on the specific product, but cement based liquid screed generally dries at a broadly similar rate to calcium sulphate, and by some manufacturers’ figures much faster, while remaining considerably quicker than a traditional mix. Because the figure varies between specific products, you should always check the manufacturer’s own drying guidance for the exact product you’re using. (By the way, a note about drying times: Manufactures usually base their estimates of drying times on 60% relative humidity and a +20 degree temperature. Differences in humidity or temperature will change the drying times!)

Traditional sand and cement screed

Still a widely installed screed in the UK, and for good reason.

Traditional sand & cement screed is the most affordable option, plus familiar to most contractors, and it’s also a sensible choice for sloped or wet room floors. The trade-off is time and labour, though. It takes considerably longer to dry, especially at greater thickness, and getting a good result with it depends on it being mixed and laid well, since poor installation increases the risk of voids and cracking.

Screed installation methods

As well as choosing the material, most screeds are laid using one of three installation methods, and the same calcium sulphate, cement based or sand and cement mix can often be installed in more than one way depending on the substrate and insulation involved.

Bonded screed

This is fixed directly to the base using a bonding agent or primer, giving a strong, thin build up that suits high load areas such as driveways and car parks. Sand and cement bonded screeds are typically laid at 25 to 40mm. Flowing calcium sulphate screeds laid as a bonded screed are less common, but where they are, figures range from around 15mm for specialist products up to 25mm for standard ones.

Unbonded screed

Unbonded screed sits on top of a damp proof membrane (DPM) rather than bonding to the base, which helps if rising damp is a concern. Because it isn’t fixed to the substrate, it needs a bit more depth for stability, usually a minimum of 50mm for sand and cement, or around 30mm for calcium sulphate.

Floating screed

Floating screed is laid over a layer of insulation, which makes it the standard choice if underfloor heating or sound insulation is involved. It needs the most depth of the three, generally at least 65 to 75mm for sand and cement, though calcium sulphate floating screeds can often be laid thinner at 35 to 40mm thanks to their self-levelling properties.

These are typical ranges rather than fixed rules, and the right depth for any project should always be confirmed against the manufacturer’s specification, particularly where underfloor heating pipework, insulation or floor loading affect the build up.

Keeping screed crack-free

Regardless of which screed material and method you decide to go with, screed expands and contracts as it dries and as temperatures change, so movement needs to be built in rather than left to chance. This is where expansion and control joints come in, as they break the floor into manageable sections and isolate the screed from walls, columns and doorways, reducing the risk of uncontrolled cracking. This applies to sand and cement and liquid anhydrite screeds alike, and is especially important where underfloor heating pipework crosses between rooms with separate heating zones.

Our expansion and control joints are designed to make this part of the job straightforward, and you can read more in our guide on why expansion and control joints matter.

Which screed is right for your project?

If you’re working around underfloor heating and don’t have moisture exposure to worry about, calcium sulphate is usually the strongest choice, but if you need that same pumped, self-levelling finish somewhere wet, then a cement-based liquid screed is the better fit. And for sloped floors or where budget is the main driver, traditional sand and cement is still a solid, proven option. Once you’ve settled on a material, then bonded, unbonded or floating will usually be decided by the substrate, insulation, and any damp proofing already in place.

Our range of screed and concrete tools is built to help you get a flat, reliable finish for whichever screed you’re working with, from levelling tripods for liquid screed and dapple bars for traditional mixes, through to expansion and control joints to keep the finished floor crack-free.

We’re here to help with any questions you might have about our screed tools, so please don’t hesitate to get in touch!

Frequently Asked Questions

Which screed dries fastest?

There isn't a single fastest screed as it depends on the specific product. Calcium sulphate liquid screed is typically walkable in 24 to 48 hours, and cement based liquid screeds like Cemfloor or Tarmac Topflow are equally fast or even quicker with some products, especially with greater thicknesses. Both calcium sulphate screed and cement-based screed are dramatically faster than traditional sand and cement screed. Exact drying time before covering still depends on thickness, the specific product and site conditions like temperature and humidity, so always check the specific manufacturer's guidance.

Can liquid screed be used in a bathroom or wet room?

Cement-based liquid screeds like Cemfloor can be used for bathrooms or wet rooms. Calcium sulphate screeds like Gyvlon are generally not suitable for wet rooms as they're water soluble. Traditional sand and cement remains the standard choice for sloped wet room floors.

Is traditional sand and cement screed still worth using?

Yes. It's still the most economical option compared to calcium sulphate or cement-based screeds and the practical choice for wet or sloped areas, though it takes longer to dry and needs careful installation to avoid cracking.

What's the difference between bonded, unbonded and floating screed?

Bonded, unbonded and floating screed describe how the screed is installed rather than what it's made from. Bonded screed fixes directly to the base and can be laid thin. Unbonded screed sits on a damp proof membrane and needs a bit more depth. Floating screed goes over insulation, which is the standard approach for underfloor heating, and needs the most depth of the three.