Gyvlon Screed: What It Is and When to Use It

Gyvlon screed — also known as anhydrite screed or calcium sulphate screed — is a self-levelling liquid screed that has become the preferred choice for large-area commercial and residential projects in the UK. Its speed of installation, thin application depth, and excellent compatibility with underfloor heating make it a genuinely superior choice for many applications.

What Is Gyvlon Screed?

Gyvlon is a branded anhydrite binder manufactured by Saint-Gobain. When mixed with aggregate and water, it forms a fluid screed that is pumped and poured rather than laid by hand. It self-levels to a smooth, flat finish and achieves SR1 surface regularity as standard — the highest surface finish classification under BS 8204. Because it flows around obstacles and under obstructions, it is particularly effective over complex underfloor heating pipe layouts.

Key Technical Advantages

Gyvlon can be laid at 25mm over UFH pipes — significantly thinner than the 65–75mm required for sand and cement floating screed. This reduces floor build-up, which matters on projects with tight floor-to-ceiling heights. It has a faster installation rate than traditional screed: a two-person crew can pump and float up to 2,000m2 per day. Thermal conductivity is also higher than sand and cement, meaning underfloor heating systems respond faster and run more efficiently.

SR1 and SR2 Surface Regularity

BS 8204 defines two surface regularity ratings for screeds: SR1 (maximum 3mm deviation under a 2m straightedge) and SR2 (maximum 5mm deviation). Gyvlon achieves SR1 as standard, which is required for direct stick floor finishes such as engineered timber, LVT, and certain tiles. For commercial projects where procurement teams specify SR1, gyvlon is usually the most practical and cost-effective way to achieve it.

Important: Laitance Removal

Gyvlon screed forms a weak surface layer called laitance as it dries. Before any floor finish is applied, this laitance must be removed by light sanding or grinding. Failure to do so will cause adhesive failures and debonding of floor finishes. This is a straightforward process that takes place once the screed has dried, typically after 28 days. screeding.com advises all clients on this process and provides guidance notes with every completed project.

screeding.com installs gyvlon screed on projects across the UK. Get an instant ballpark price using our quote tool, or contact us to discuss your project.