We had a new concrete floor laid in our property in early June 2024 using Gyvlon Screed sourced from Anhydritec Ltd. The floor was scarified/sanded about two weeks later. To the naked eye the floor is perfectly level and smooth. The depth of the concrete screed varies from 35mm up to 100mm in a new extension. The floor in the extension had a membrane, as well as insulation inserted, with concrete screed poured on top. The rest of the old flooring in the property was black jacked to provide a moisture barrier. We were poised to lay Amtico LVTs and the floorers duly primed the floor and laid a latex screed early in September. Moisture levels using three different meters were all within range. It was only by chance when the floorers asked for a kitchen cabinet to be moved about one foot did we discover that the screed was lifted by one of the legs. Further investigations revealed that all 1,250 sq feet of latex screed (with the exception of just a couple of patches) had failed to bond to the concrete. All of the latex screed has since been removed. The floors were then resanded at least 7 times as there was evidence of white latence of the back of the removed latex screed. The floorers, who are very experienced and understandably cautious, have since laid 6 test patches using the the recommended primer and latex screed. We discovered late yesterday that all 6 patches have failed to adhere. Any thoughts on why this may have happened and what might be an alternative solution? A meeting has been convened with the company that has laid the concrete screed and the floorers. All parties have acted professionally and promptly throughout and at this point in time are at a loss as to why the latex has failed to bond. Again, anyone out there who has had a similar experience and any thoughts on why this might have happened? And what solutions might there be?
Did they use two coats of primer? Do you have under floor heating? How was the moisture reading taken. How long did you leave the new screed to dry?
At least two, sometimes three. No underfloor heating. Moisture meter readings taken wth three different meters at several points throughout the property following the recommended instructions. The new screed was down for 24 hours. In fairness the floorers have been back in to re-inspect the test patches some 48 hours later and it appears that some areas have started to bond. There was no heating in the property and they are starting to believe that it is taking longer than normal to cure in the cooler temps, but it has been since set to 20C, but I'm going to drop the target temp to 18C.
What moisture meter was used. All sounds like it’s not been given enough time to dry out enough. so you have a old screed meeting a new one ?
Are there any black spots in the gyvlon screed? Did they put a box on the floor for 3 days then take a test?. Black jack on the old part isnt part of a ardex system. Not sure how well the cl will bond to that.
Hi Vic, I’m really sorry to hear about the issues you’re experiencing with your flooring project—it sounds incredibly frustrating. Let’s see if we can pinpoint some potential causes and explore possible solutions. Possible Reasons for Latex Screed Failure Surface Preparation Issues: Contamination: Even with thorough sanding, any remaining dust, grease, or residues from the black jacketing could hinder adhesion. White Latent Residue: The white latence you observed suggests moisture or efflorescence, which can prevent proper bonding. Moisture Problems: Hidden Moisture: Although initial moisture readings were within range, moisture can migrate over time or from different sources, especially with varying screed depths. Membrane Integrity: In the extension, the fragile polythene membrane might still allow some moisture ingress, affecting adhesion. Primer and Product Compatibility: Incorrect Primer Application: The primer might not have been compatible with either the concrete screed or the latex screed product. Product Compatibility: There could be an incompatibility between the Gyvlon Screed and the latex screed used. Environmental Factors: Temperature and Humidity: Fluctuations during application can impact the curing and bonding of the screed. Application Timing: If the latex screed was applied too soon after the concrete screed was laid, it might not have had sufficient time to cure properly. Structural Movement: Screed Depth Variation: The significant variation in screed depth (35mm to 100mm) might lead to differential movement or stress points, affecting adhesion. Recommended Next Steps Comprehensive Surface Inspection: Clean Thoroughly: Ensure the entire concrete surface is free from any contaminants. A professional surface preparation service might be beneficial. Assess Moisture Sources: Re-evaluate moisture levels, especially in areas where the membrane is present. Consider using a calcium chloride test for more accurate moisture measurement. Consult with Manufacturers: Product Guidance: Reach out to both Gyvlon Screed and the latex screed manufacturer to discuss the compatibility and application conditions. Technical Support: They might offer specific primers or alternative products better suited for your setup. Alternative Screed Solutions: Different Polymer Screeds: Explore other types of polymer-based screeds that might offer better adhesion with your existing concrete. Epoxy-Based Systems: These can provide strong bonding and are highly durable, though they may require different preparation and application techniques. Professional Consultation: Damp-Proofing Specialist: Bringing in a specialist can help identify any hidden moisture issues that might not have been apparent initially. Structural Engineer: They can assess if the screed depth variations are contributing to the problem and recommend structural adjustments if necessary. Re-application Strategy: Controlled Environment: Ensure that the room conditions (temperature and humidity) are optimal during the re-application of the screed. Staggered Application: Consider applying the screed in smaller sections to manage and monitor adhesion more effectively. Alternative Solutions Floating Floor Systems: If screed bonding continues to be problematic, you might consider floating LVT systems that don’t require a bonded screed. Glue-Down Methods: Depending on the LVT specifications, a different adhesive method might bypass the need for a traditional screed layer. Underlay Adjustments: Sometimes, modifying or enhancing the underlay can improve moisture management and provide better support for the flooring. Hope this helps! Steve www.pro-fitfloorcoverings.co.uk
