Comprehensive Guide to Anhydrite Floor Screed

A Comprehensive Guide to Anhydrite Floor Screed

In the construction world, when laying the groundwork, the choice of anhydrite floor screed can significantly impact the efficiency, sustainability, and lifespan of a building. Enter anhydrite floor screed, a high-performing material gaining traction for its numerous advantages over traditional solutions. This comprehensive guide will walk you through every aspect of anhydrite screed, from understanding its properties to troubleshooting common issues that may arise. Whether you’re a seasoned construction professional or a newcomer, this resource will equip you with the knowledge to work effectively with anhydrite floor screed. 

What is Anhydrite Floor Screed?

Anhydrite floor screed, known as calcium sulphate or flowing screed is a self-leveling compound used as a smooth and thin underlayment for various floor coverings. Unlike cement-based screeds, anhydrite is made from anhydrous calcium sulphate and has several distinctive qualities that make it an excellent choice, especially for modern construction needs.

Properties and Comparison to Traditional Screeds

Anhydrite floor screed is typically a more cementitious material, often produced as a calcium sulphate bonded compound based on 70-80% anhydrite and other cementitious binders. The key properties that set it apart from traditional sand cement screeds are its fluidity, self-leveling nature, and improved thermal conductivity due to its higher thermal conductive properties. It also does not require mechanical compaction, saving time and labor costs. 

One of the main differences between anhydrite and cement-based screed is drying time. Anhydrite screed dries much faster than sand and cement screeds, usually allowing for the installation of floor finishes in a shorter time frame.

The Installation Process of Anhydrite Floor Screed

Proper installation is crucial for the performance of anhydrite floor screed. This section will outline the steps involved in the installation process and address the considerations to remember

 Preparation Phase

The preparation phase is key to a successful installation. It includes surface cleaning to ensure no obstacles or contaminants could interfere with the screed’s bonding. During the phase, you should check the subfloor’s flatness, with any discrepancies addressed before installation.

Laying the Screed

The screed can be poured onto the subfloor, often using a pump for larger areas. Given its fluid nature, the screed will self-level, minimizing work and reducing the risk of weak points or uneven spots.

Drying and Curing

Anhydrite floor screed needs time to dry and cure before floor finishes can be installed. The duration of this process can vary due to factors like thickness, temperature, and humidity. Usually, a moisture content of no more than 0.5% by weight is the accepted level for laying most floor finishes.

Anhydrite screed drying time is significant. Generally, it takes around 24 to 48 hours for the screed to be walkable, and it can be covered with floor coverings within 7 days, depending on the environment and thickness.

Benefits of Anhydrite Floor Screed

Anhydrite floor screed offers several benefits making it an attractive choice for commercial and residential construction projects. 


One of the primary advantages is its self-leveling property, which ensures a flat and even surface without the need for extensive manual labor.

Faster Installation

Anhydrite screeds can be laid more quickly than traditional screeds, reducing construction time. It can be pumped over large areas quickly, reducing labor costs and time on site.

Improved Thermal Conductivity

The composition of anhydrite floor screed allows for better heat distribution, making it ideal for underfloor heating systems. moreover, its excellent thermal conductivity makes it an ideal choice for underfloor heating systems, as it allows for a uniform heat distribution across the floor.

Smoother Finish

Comparatively, anhydrite floor screeds typically result in smoother and more level surface cement-based screeds than traditional screeding.

Reduced Shrinkage

Anhydrite screeds exhibit minimal shrinkage during the process, reducing the risk of  Screed Cracking, and ensuring a smooth, durable surface ideal for various flooring finishes.

Common Issues and Solutions

Despite its many benefits, anhydrite floor screed can be prone to certain issues if not handled. This section will cover some common problems and how to address them.

Moisture Retention and Its Impact on Floor Finishes

Anhydrite screed is particularly sensitive to moisture, especially in its early stages. Excessive moisture can lead to problems like debonding and mold or mildew. Monitoring the drying process and relative humidity with the appropriate tools is critical. 

Shrinkage and Cracking

Similar to other screed materials, anhydrite is prone to shrinkage and cracking when conditions are less than ideal. Proper curing and timing play crucial roles in minimizing these risks. Contractors may opt to include reinforcement fibers or utilize a crack suppression membrane to mitigate the likelihood of cracks. Ensuring the appropriate conditions are upheld during installation is paramount to minimizing the risk of anhydrite screed cracking.

Smoothness and Flatness

One of the key selling points of anhydrite liquid screed is its self-leveling ability. However, achieving a perfectly flat and smooth surface is still a skillful task. Techniques such as laser levels during pouring and regular checks throughout the drying process are recommended to ensure uniformity.

Sustainability and Environmental Considerations

Sustainability is a growing concern in the construction industry, and anhydrite floor screed offers some eco-friendly benefits. The faster drying times mean reduced project schedules and lower energy usage over the life of the building. Additionally, anhydrite screed can be sourced from recycled gypsum, lessening its environmental impact.

Maintenance Tips for Anhydrite Floor 

Routine maintenance is essential to prolong the life and maintain the integrity of anhydrite floor screed. Regular inspections for damage, keeping the surface clean, and avoiding heavy impact are all part of the maintenance routine. Additionally, following the recommendations for the type of floor covering you’ll be using is important in preventing damage to both the screed and the finish.

Notable Projects and Practical Insights

Learning from notable projects that have used anhydrite floor screed can provide valuable insights. Case studies can showcase best practices, innovative uses, and the overall performance of anhydrite screed in different environments.

Whether it’s ensuring a smooth application or troubleshooting potential problems down the line, a solid grasp of this material can significantly impact the outcome of your projects. By adhering to the guidance in this complete guide, you’ll be well on your way to harnessing the full potential of anhydrite floor screed in your construction endeavors.