Advantages of Anhydrite Screeds

Anhydrite screed offers several advantages that make it a preferred choice for many construction and renovation projects. These include:

a. Rapid Installation:

Anhydrite screed can be applied quickly, allowing for faster project completion compared to traditional screeds. It requires less time to dry and can be walked on sooner, reducing construction timelines.

b. Self-Leveling Properties:

Anhydrite screed naturally levels itself, resulting in a smooth and even surface. This property eliminates the need for extensive manual leveling, reducing labor costs and ensuring a high-quality finish.

c. Thermal Conductivity:

Anhydrite screed has excellent thermal conductivity, making it an ideal choice for underfloor heating systems. It efficiently transfers heat, providing optimal comfort and energy efficiency.

d. Reduced Shrinkage and Cracking:

Anhydrite screed exhibits minimal shrinkage and cracking compared to traditional cement-based screeds. This characteristic ensures long-term durability and reduces the need for repairs or maintenance.

Applications of Anhydrite Screed

Anhydrite screed is suitable for various applications in both commercial and residential settings. Some common applications include:

a. Domestic Flooring:

Anhydrite screed provides a smooth and level base for a wide range of floor coverings, such as carpets, laminate, vinyl, and tiles. Its versatility makes it suitable for bedrooms, living rooms, kitchens, and other areas of the home.

b. Commercial and Industrial Flooring:

Anhydrite screed can withstand heavy loads, making it ideal for commercial and industrial environments. It is commonly used in offices, retail spaces, warehouses, and factories, providing a durable and long-lasting flooring solution.

c. Renovation Projects:

Anhydrite screed is often used in renovation projects to level uneven or damaged substrates before installing new flooring. Its self-leveling properties help to overcome surface irregularities and provide a stable base for the desired floor finish.

Anhydrite Screed Installation Guide

Here is a step-by-step guide to installing anhydrite screed:

a. Surface Preparation:

Ensure the substrate is clean, free from dust, and structurally sound. Repair any cracks or damaged areas. If necessary, apply a suitable primer to enhance adhesion.

b. Edge Preparation:

Install edge insulation strips around the perimeter of the area to prevent screed from leaking out.

c. Mixing:

Follow the manufacturer’s instructions for mixing the anhydrite screed. Use clean water and a suitable mixing device to achieve a smooth and consistent mix.

d. Pouring and Leveling:

Pour the mixed anhydrite screed onto the prepared substrate. Use a leveling device, such as a straightedge or laser level, to achieve the desired thickness and evenness. Allow the screed to self-level.

e. Finishing:

Once the screed has settled, smooth the surface using a trowel or power float. This process helps to achieve a seamless finish and further levels the screed.

f. Drying and Curing:

Follow the manufacturer’s guidelines for drying and curing times. Anhydrite screed typically requires less drying time compared to cement-based screeds. Avoid foot traffic and heavy loads until the screed is fully cured.

g. Floor Covering Installation:

After the screed has dried and cured, you can proceed with the installation of the chosen floor covering according to the manufacturer’s recommendations.

Tiling on anhydrite screeds

Anhydrite screeds have become quite common as they offer benefits over sand and cement screeds. However, tilers must be aware of a number of potential anhydrite screed problems.

Common issues and queries you can face

Anhydrite screeds have gypsum content

Anhydrite screeds have gypsum content

When a cement-based adhesive is applied directly onto the floor, cement in the tile adhesive reacts with the gypsum in the screed resulting in a mineral called ettringite being formed at the interface. The associated structural change is sufficient to cause a complete debond of the cementitious adhesive away from the screed base.

Anhydrite has a weak surface layer

Anhydrite has a weak surface layer

As anhydrite cures, a weak layer of laitance is formed on the surface. This layer is too weak to tile onto and also slows the drying time of the screed.

Anhydrite screeds may be difficult to identify

Anhydrite screeds may be difficult to identify

Firstly, what is anhydrite screed? Anhydrite screeds are made from inert fillers such as sand, with a binder system based on calcium sulphate. Consequently they can look very similar to a sand/cement screed. Anhydrite will tend to appear lighter, sometimes almost white, but in practice it is difficult to identify an existing anhydrite screed from a traditional one.

If a screed is known to be anhydrite it must be thoroughly sealed before the application of a cement-based tile adhesive. If the screed type is not known and it is believed that it could be anhydrite, the screed should be thoroughly sealed as a precaution.

Assess and prepare floor

Assess and prepare floor

  1. The cured screed will have a layer of anhydrite screed laitance that will need to be removed after 2-6 days (dependent on brand of screed used). This will provide a dense surface to tile onto and will aid drying.
  2. Ensure the floor is fully dry – the residual moisture level should be less than 0.5%. Drying times vary according to the brand of screed used. Some are designed for fast-track use, whilst others require the standard drying times. If no other information is available assume the screed will take 1 day per mm up to 40mm in thickness to dry in normal conditions. Screeds thicker than 40mm will require 2 days per mm.
  3. Seal the floor with weber PR360 — which can be used as an anhydrite floor primer — repeatedly until no more is absorbed and allow the primer to dry before tiling. An uncoupling membrane can be used to reduce stress on the tiling layer and to ensure that ettringite does not cause a failure.

Laying tiles

Fix tiles into a solid bed of weberset pro lite – rapid or weberset rapid SPF at least 3 mm deep. Leave joints at least 3 mm wide for grouting and make provisions for movement.

Apply grout and silicone

Fill the joints between tiles with weberjoint premium, and use weber joint silicone sealant to fill perimeter movement joints.


Anhydrite screed offers numerous advantages and applications, making it a popular choice for flooring projects. Its self-leveling properties, rapid installation, and thermal conductivity contribute to its appeal. Whether it’s for domestic, commercial, or renovation purposes, anhydrite screed provides a smooth, durable, and high-quality surface. By following the installation guide and utilizing the expertise of professionals, you can achieve an excellent finish that meets your specific flooring requirements.

Installing flooring can be a long and difficult process.

It takes days to dry, sanding is required, and it’s hard to get the job done quickly. Plus, underfloor heating can add even more complexity.

Cemfloor is the perfect solution! This cement-based flowing screed can be walked on after 24-48 hours with 21 day drying times (depending on site conditions). There’s no need for sanding once installed, plus it’s suitable for underfloor heating – with force dry after 7 days using UFH and lay floor coverings after 14 days with the UHF commissioned. We also have specialised products for thin self levelling depths of 12mm so you can get your job done quickly and easily – we can lay up to 1200m2 a day!

Contact us now to learn more about Cemfloor!