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What Is Screed?

If you're wondering, what is screed?—you're not alone. The term is not widely known but refers to floor underlayment. Screed is nothing more than a substrate layer applied on ceilings or concrete slabs. It is made from a mixture that hardens over time, forming a dense base layer for flooring or carpet installation.

Types of Screeds

Depending on the material used, there are several different types of screeds:

• Cement screed – also known as concrete screed, made with Portland cement.
• Gypsum screed – forms a thick base layer.
• Magnesite screed – a mixture of magnesium oxide and magnesium chloride with organic and inorganic fillers.
• Asphalt screed – made from poured asphalt, stone dust, and sand, applied hot.
• Anhydrite screed – contains synthetic or natural anhydrite, which binds with retarders to control setting time.
• Self-leveling screed – creates a perfectly smooth surface.

Characteristics of Anhydrite Screed

One of the most commonly chosen screed types is anhydrite screed.

• Minimal shrinkage after drying, reducing the risk of cracks.
• No need for additional reinforcement, making installation easier.
• No need for expansion joints, unlike some other types of screeds.
• No surface deformations, ensuring long-term stability.
• Can be walked on after just 24 hours, speeding up construction work.

Anhydrite screed has a relatively thin consistency, which naturally forms a level surface, eliminating the need for additional leveling. It is suitable for underfloor heating, ensuring optimal heat distribution.

However, it should not be used in high-moisture areas or outdoors, as it does not tolerate prolonged exposure to water. Another drawback is its relatively high cost compared to other screed types.