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Calcium sulphate flowing screed

Calcium sulphate flowing screed (CAF, CFE) consists of sand/gravel, water and calcium sulphate as a binder. It has a flowable consistency, which makes it self-levelling and self-compacting. Calcium sulphate flowing screeds are marked with the CE mark in accordance with EN 13813. This marking guarantees consistent properties that are monitored according to standardized quality requirements.

Areas of application for calcium sulphate flowing screed

Calcium sulphate flowing screed can generally be used in all residential and commercial buildings. This also includes domestic damp rooms (e.g. kitchens, toilets). In rooms where splashing water is to be expected (e.g. bathrooms), the screed must be protected by waterproofing. Calcium sulphate flowing screed is not suitable for really wet rooms (e.g. swimming pools).

Incidentally, calcium sulphate flowing screed is the ideal screed if underfloor heating is to be installed. This is because it has a high thermal conductivity and heat storage capacity. This has the advantage that it does not have to be laid as thickly, which means that the distance between the heating pipe and the surface is smaller. This means that the heat reaches the surface quickly. Shorter heating times and lower flow temperatures go hand in hand with lower energy consumption, which is good for both the environment and your wallet.

Laying techniques for calcium sulphate flowing screed

Calcium sulphate flowing screed can be used in many constructions and installation techniques. Which one is chosen depends on the function of the component and the expected loads. In principle, calcium sulphate flowing screed is suitable for all screed constructions in accordance with DIN 18560. The following table provides an overview of the possible installation techniques / screed constructions and the areas in which they are most frequently used:

Laying technique | suitable for

  • Bonded screed | Areas where heavy loads rest on or are moved on the floor
  • (floating) screed on insulating layer | Residential and commercial construction with thermal and sound insulation requirements
  • Screed on separating layer | Areas where no bonded screed is possible, where there are no thermal or sound insulation requirements or where thickening must be installed
  • Heated screed | underfloor heating
  • Cavity floor construction | Administration and utility building

Note: Depending on the area of application or use, the final screed thickness specified in the respective standards changes.

What to look out for when laying calcium sulphate flowing screed

The calcium sulphate flowing screed is supplied either as factory dry mortar in bags or silos or as factory fresh mortar from the truck mixer. The latter has the advantage that no space is required for raw materials and no waste is produced.

Calcium sulphate flowing screed is relatively insensitive to outside temperatures. Even processing at outside temperatures below freezing (0 °C) is not a problem as long as the room and mortar temperature is at least 5 °C during processing.

As a general rule, the screed should be laid as thinly as possible but as thickly as necessary. The final screed thicknesses specified in DIN 18560 must of course be observed, but should not be significantly exceeded. Otherwise the drying times will be considerably longer.

Proper ventilation is essential for quick drying. The following tips will help:

  1. in the first 48 hours: Protect screed from draughts
  2. from the 3rd day: intensive ventilation (depending on the weather, either several times a day or continuous ventilation)
  3. Until completely dry: protect screed from rainwater

The advantages of calcium sulphate flowing screed

Calcium sulphate flowing screed is characterized by its high flexibility, thanks to which the final screed thickness can be up to 20% less than with conventional screed. This allows more construction height, which can be used for additional thermal or impact sound insulation if required.

Its flowability allows the screed to form a level surface quickly and easily without the need for great physical effort.

Calcium sulphate flowing screed forms a homogeneous, dense structure that quickly develops the necessary tensile and compressive strength. Reinforcement is not required. The screed can be walked on after just 2 days and loaded after 4-5 days - this means that construction progress is faster than with other types of screed.

Another major advantage is that calcium sulphate flowing screed does not suffer from the so-called bowl effect. This means that the edges and corners do not lift, meaning that no countermeasures need to be taken or corrections made. This saves effort, time and money - not only during installation, but also in the years to come.

Your contact for screed work of all kinds

Are you interested in the benefits of calcium sulphate flowing screed or would you like general advice on different screeds? Then you've come to the right place. We have extensive know-how and over 25 years of experience in advising on and carrying out all types of screed work. From the initial consultation to the acceptance of the finished screed - we will be happy to provide you with advice and assistance at any time.

Convince yourself of the professionalism, quality and reliability of our work, which each of our employees fulfills with passion and pride. Contact us and arrange a personal consultation, we look forward to supporting you with your project!


Questions and answers about calcium sulphate flowing screed

Which dries faster - calcium sulphate screed or calcium sulphate flowing screed?

Calcium sulphate screed dries faster than calcium sulphate flowing screed. However, the latter hardens more quickly and can therefore be walked on and loaded earlier.

Can calcium sulphate flowing screed be laid in combination with underfloor heating?

Yes, very well indeed. The first heating up is possible after just 5-7 days. As calcium sulphate flowing screed can conduct and store heat very well, it can be laid thinner than other screeds. This saves energy and money.

Cement flow screed vs. calcium sulphate flow screed - which is better?

This cannot be said in general terms, as both types of screed have their advantages, so it always depends on the area of application and requirements. Calcium sulphate flowing screed - unlike cement flowing screed - is not resistant to moisture and therefore cannot be used in damp or wet rooms. On the other hand, calcium sulphate flowing screed is significantly less prone to shrinkage and cracking. In addition, calcium sulphate flowing screeds can be laid without any expansion joints, which are required for cement flowing screeds.