Pro Gyp-Base: The Ultimate Time-Saving Solution for Anhydrite Screeds from Palace Chemicals

For large areas, liquid pumped anhydrite screeds offer a number of advantages to flooring contractors, principally that they are quicker and easier to install, especially above underfloor heating systems.

Flowing anhydrite screeds have been on the market for about 35 years and now account for an estimated 20% of the market. Recognised for their sustainability benefits, these screeds often incorporate recycled materials, making them an environmentally responsible choice.

Their main downside is that they tend to require a much longer period to dry out to an acceptable moisture level and, even when considered dry, they still cannot be directly over-laid with a cement based floor leveller (or adhesive), due to an incompatibility reaction which can occur between the cement leveller and gypsum-based pumped screed, causing the formation of the expansive salt ettringite, which fractures any bond between the two materials.

To achieve the required maximum relative humidity of 75% prior to tiling, BS 8204-7:2003 states that the minimum required drying time for anhydrite screeds is one day for each millimetre up to 40mm thickness, with an additional 2 days per mm thickness above 40mm. In ideal drying conditions therefore, a 40mm thick screed should be allowed to dry for a minimum of 40 days. At 50mm thick the minimum drying time would be 60 days and at 60mm thick, a minimum of 80 days drying time would be required before the screed was sufficiently dry to receive a tiled finish. Failure to follow these recommendations will generally result in adhesion failure at the screed/adhesive interface.

By comparison, sand:cement screeds require a minimum drying period of 21 days, as outlined in BS 5385-3:2003.

These factors necessitate the use of specialist “multi-layer” preparatory surface treatments, designed to create a lasting and effective barrier seal over the gypsum screed base before other layers of the floor build-up can be completed.

This is where Palace’s Pro Gyp-Base comes into its own. A recent introduction to the Palace Chemicals flooring range, this product is a game changer. It makes it possible to tile with a cement-based adhesive on to areas which have a relative humidity as high as 95%. This can normally be achieved as quickly as seven days after pouring, at which point tiling can commence. This system accelerates the overall completion of the floor surface by up to ten weeks, delivering a substantial improvement in project timelines and significant cost savings on-site.

Use of this system gives contractors the advantage of rapid, easy pouring of an anhydrite screed application – while eliminating the typical downtime on the job caused by extended drying periods.

Palace Pro Gyp-Base works as a four-part system, comprising two epoxy primers (clear and black), a polyurethane-based moisture suppressant and a rapid-drying textured primer to provide a ‘key’, on to which the tile adhesive can form a strong bond. Recommended S1 adhesives include Palace Multi Flex or Easi-Flex. A single Pro Gyp-Base kit is sufficient to prepare 25m² floor area.

For more information please visit: https://palacechemicals.co.uk/shop/palace-tiling/flooring/palace-pro-gyp-base-fast-track-sealer/