Gypsum vs. Cement Based Screed – What’s The Difference?

Posted on: 5th May 2022

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Last updated: June 2026

Liquid or pumpable screeds are becoming more and more popular. For example, they can be laid to a thinner depth and are quicker to lay than traditional screeds, and they’re especially handy when installing underfloor heating. But how are cement based screed and calcium sulphate screed different from each other and how do you know which one’s best for you and your project?

Quick Answer: Liquid screeds broadly come in two types: gypsum-based (also called calcium sulphate or anhydrite screed) and cement-based. Gypsum-based screeds have been the standard since the early 1990s. They are stable, shrink less than cement, and work well with underfloor heating. Cement-based liquid screeds, introduced more recently, dry faster, do not need surface preparation before the floor finish goes down, and can be used in wet rooms. Both are significantly faster to lay than traditional sand and cement screed, but cement-based products currently command a price premium and are less widely available.

What’s gypsum-based screed?

Gypsum-based flowing screeds were first introduced into the market in the early 1990s. This type of liquid screed has calcium sulphate as the active ingredient, making up around a third of its volume. When you add water, it becomes gypsum, so it tends to go by names like “calcium sulphate screed”, “gypsum screed” or even “anhydrite screed”. Using gypsum as a binder helps eliminate some of the problems that cement can cause. For example, gypsum-based materials don’t shrink like cement does when drying and becoming solid. The stable nature of gypsum makes the formulation of flowing screed easier.

OK, so what is cement based screed?

Past attempts to produce liquid screeds based on cement failed to be reliable in use due to shrinkage issues. The first real solution was launched in 2011 by a French cement-based materials company Cemexa, who used a new system of chemistry to control the shrinkage of the cement and give the flowing screed a stability and robustness similar to gypsum-based screeds.

How to Pour or lay liquid screed

 

Compared to gypsum, cement–based flowing screeds using Cemexa’s technology (for example Cemfloor by McGraths in the UK) is proven to be more reliable and quicker when drying. It also makes the preparation for floor finishes easier, as once the material is dry the surface doesn’t need preparation the way it does with Anhydrite-based screeds. This does often mean a higher price, although it also reduces labour time.

Different manufacturers and suppliers (Tarmac, Breedon, Cemex, etc) have different proprietary products (Topflow Screed, BreedonFlow, Belitex, etc) so there is variation in the benefits of each.

The choice of which one to use is based on the different pros and cons of the various options.

For more detail on the advantages & disadvantages of different types of screed, please click here.

For trusted floor screeding tools used by professional screeders and groundworkers to level, dapple and spray free flowing liquid screeds, click here.

Frequently Asked Questions

Both are pumpable, self-levelling screeds that offer significant advantages over traditional sand and cement screed in terms of speed and accuracy. The key differences come after laying. Gypsum-based (anhydrite) screed forms a layer of laitance on the surface as it dries which needs to be sanded off before the floor finish goes down. Cement-based screed does not have this problem, dries roughly twice as fast, and can be used in wet rooms. It currently costs more and is less widely available, but the gap is closing.

Anhydrite screed is another name for calcium sulphate or gypsum-based liquid screed, for example Gyvlon. The name refers to the form of the mineral used in the mix: anhydrous calcium sulphate, which becomes gypsum when water is added. It has been the dominant type of liquid screed in the UK since the early 1990s and is widely available from most screed suppliers. It works particularly well with underfloor heating and is less prone to shrinkage than cement.

Both work well with underfloor heating. Liquid screed of either type flows around UFH pipes and encapsulates them fully, which improves heat transfer compared to a hand-laid screed. If drying time is a priority on a tight programme, cement-based screed has an advantage as it can dry at around 2mm per day compared to around 1mm per day for anhydrite. For most domestic UFH installations, either type is suitable.

Yes. As anhydrite screed dries, a thin layer called laitance forms on the surface. This needs to be removed by sanding before any adhesive or floor finish is applied, as it is too weak and porous to bond to directly. Once laitance is removed, the surface also needs to be sealed before adhesive goes down, since the screed will otherwise absorb moisture from the adhesive and cause it to fail. Cement-based screed does not require this preparation step.

Cement-based liquid screed can be used in wet rooms as it is waterproof and its drying time is not affected if it gets wet. Gypsum-based anhydrite screed is not suitable for wet rooms, as prolonged moisture exposure can affect its performance and its drying cycle can be reset if it becomes wet before it has fully cured. For any wet area, cement-based screed is the safer choice.

Liquid screed can be laid thinner than traditional sand and cement screed. Gypsum-based screeds are typically laid at a minimum of 35mm over underfloor heating pipes, or 25mm where no UFH is present, depending on the product and substrate. Cement-based screeds can in some cases go thinner still. Always follow the manufacturer's minimum depth guidance for the specific product and application, as going too thin increases the risk of cracking and surface failure.

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