Frequently Asked Questions (FAQ)
What is Gyvlon® Screed?
Gyvlon® Screed (trademark) is the trade name for the screed range of ANHYDRITEC®. Gyvlon® Screed has been established and recognised in the UK for over 25 years.
What depths of screed are recommended?
Fully Bonded 25mm, mechanical contact with substrate/unbonded 30mm. Over insulation/acoustic matting 35mm domestic and 40mm commercial. Covering over top of the pipes with Gyvlon® Screed Thermio®+
What depth of screed coverage is required over underfloor heating?
Our standard solution, ECO®, requires a minimum of 25mm (by British Standard). BBA Approved Thermio®+ Technology can be installed with just 20mm coverage.
How long before I can walk on the floor?
The screed can be walked on 24 to 48 hours after the installation, dependant on site conditions.
Is it true that I have to sand the screed?
Yes. As per British standard surface laitance should be removed after 7-10 days to help the screed dry out. If Low Laitance additive is used then sanding to create a mechanical key is all that is required prior to floor coverings being applied.
How long before I can tile?
In good drying conditions 20deg 60%RH Gyvlon® Screed products dry at the same rate as traditional sand and cement screed approx. 1mm/day up to 40mm of thickness. This increases for screeds thicker than 40mm and in poor drying conditions. When the screed is dry then you can tile. If underfloor heating is installed, it is recommended that the heating system is commissioned before installing surface finishes. It is important to have all the moisture out of the screed as the tiles may not bond with the adhesive.
Do I have to commission underfloor heating before tiling?
Yes if installing impermeable surface finishes, such as tiles. All pipes should be pressure tested before installing screed.
Do I have to prime the screed?
Yes, if any adhesive is used for your selected choice of flooring, it is recommended to use an epoxy primer to create a barrier between any cement based adhesive and the gypsum based screed. Before this is applied it is vital that the floor is lightly sanded or scraped to key in the primer. We would recommend the use of Gypsum Tile Adhesives which are directly compatible and can be laid at 85% RH rather than 75% required for cement based adhesives.
Can I use renewable, solar or low energy sources such as Ground and Air Source Heat pumps with under-floor heating and your screed?
Yes. Thermio®+ is specifically designed to compliment these systems by running at lower water temperatures. A good heating system will ensure the property runs effectively and is environmentally efficient.
Is there help if I have a problem that I cannot find an answer to on the web?
Yes. Please refer to your local Technical Specification Manager (details on our contact us) who will assist.