Focus on floors: your questions answered

A selection of the hundreds of questions answered by F. Ball’s technical team in the past few weeks

Q. The concrete surface I am working over is weak. Can this be rectified?

A. In many cases, it will be possible to strengthen a weak screed using Stopgap SRS (surface reinforcement system) – a two-component epoxy resin reinforcement material designed to quickly stabilise and reinforce weak sand/cement or calcium sulphate screeds. Contractors simply pour the mixture over the weak subfloor, spread it out with a rubber squeegee and work it 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. In order to determine the likelihood that this will be successful, a prior assessment should be made to determine the condition of the screed. In Situ Crushing Resistance (ISCR) tests, using a BRE screed tester to BS 8204, are typically used for these purposes.

Q. Is it possible to apply a second layer of Stopgap 1200 Pro over the first one?

A. Yes. Stopgap 1200 Pro can be applied in multiple layers in thicknesses from 2-10mm. In this scenario, there is no need to prime the surface before the next application of levelling compound.

Q. Can I apply Stopgap 200 over a subfloor prior to the application of a waterproof surface membrane.

A. Although it is standard practice to apply a waterproof surface membrane prior to the application of a levelling compound where a solution for damp is required, it is also possible to reverse the processes. This may be desirable where an extremely uneven subfloor would cause a waterproof surface membrane to pool in undulations, compromising the effectiveness of the waterproof surface membrane and meaning a greater quantity of product may be required to achieve full coverage. If you are going to do this you need to select a moisture resistant levelling compound. Stopgap 200 does not offer moisture tolerant properties, but suitable alternatives include Stopgap 1200 Pro, which is moisture resistant and, like Stopgap 200, fast drying and suitable for use in biologically sensitive areas, such as hospitals and laboratories.

Q. What is the drying time of Styccobond F49 Hybrid PS?

A. When using Styccobond F49 to install floorcoverings over absorbent surfaces, such as sand/cement screeds, floorcoverings can be laid directly into the adhesive, and it will dry to form a high bond strength in 20 minutes. However, it is advisable to allow the adhesive to dry for 20 minutes before installing floorcoverings to provide grab, particularly when installing vertical flooring accessories or complex designs and patterns. Styccobond F49 allows floorcoverings and vertical flooring accessories to be repositioned in the early stages of drying (up to 20 minutes) if alignment isn’t quite correct. When using the adhesive to install floorcoverings over non-absorbent surfaces, including subfloors of terrazzo and steel, it should be allowed to fully dry to a clear film (typically 30 minutes) before installing the coverings.

Q. What adhesive should I use to install rubber floorcoverings over plywood?

A. F. Ball’s Styccobond F58 is designed to install a wide range of rubber floorcoverings over subfloors of structurally sound, smooth and dry concrete, sand/cement screed, flooring grade chipboard, hardboard and plywood. It’s an acrylic emulsion adhesive that provides a high bond strength and strong initial tack to hold rubber floorcoverings firmly in place. It will be necessary to prime the subfloor beforehand to prevent the unacceptably rapid drying of the adhesive and promote adhesion. It’s also advisable to check the compatibility of the floorcoverings with the adhesive. You can do this by consulting F. Ball’s recommended adhesives guide here.

Q: What levelling compound can be used over a damaged tile floor, where some tiles are missing?

A: Areas where tiles are missing can be filled using Stopgap 400 Repair (or Stopgap 460 Exterior Repair for external areas exposed to water). A levelling compound of choice can then be applied over the entire area to achieve a smooth surface ready for the installation of a new floorcovering. It will be essential to prime the subfloor beforehand to ensure the adhesion of the chosen levelling compound.

Our technical team are on standby to answer questions about your projects and F. Ball products from 8.30am – 5.00pm, Monday to Friday.

Please note: site conditions vary. Don’t rely on these specific responses for your own project. If you are unsure about any technical issue relating to specific flooring installations, contact the F. Ball Technical Service team on 01538 361633 or consult the product data sheets available from F. Ball’s website.