WHEN conducting a refurbishment project, upon removing old floorcoverings and old adhesives residues, contractors may discover the base below is weak or friable – the result of poor installation or curing techniques.
Traditionally, a weak or damaged screed would have to be entirely removed by mechanical means and a new screed installed before the refurbishment could proceed. Now contractors have a less costly and disruptive option: in most cases, a weak or friable screed can be prepared with a surface reinforcement system (SRS).
One such system, F Ball’s Stopgap SRS, is a two-component epoxy resin reinforcement material designed to, it’s claimed, quickly stabilise and reinforce weak sand/cement or calcium sulphate screeds and is suitable for use over underfloor heating systems.
Contractors simply mix the components thoroughly, pour the mixture over the weak subfloor and spread out with a rubber squeegee, working into the surface until no more liquid is absorbed. The product penetrates the weak/friable surface, filling voids and cracks and binding loose particles to strengthen the screed.
Stopgap SRS reportedly acts rapidly, meaning weak screeds can be reinforced overnight to provide a base suitable for the installation of subsequent subfloor preparation products. It can apparently be used over certain screeds containing high levels of construction moisture prior to the application of a waterproof surface membrane.
Contractors should follow individual manufacturer’s instructions when using surface reinforcement systems, and an assessment should be made to determine the condition of the screed, and, therefore, the likelihood of success, prior to installation.
In situ crushing resistance (ISCR) tests, using a BRE screed tester to BS 8204, are typically used for these purposes.