Behind every quality floor lays an equally sound base – it would be impossible to achieve one without the other.

A detailed assessment of the subfloor is essential to successful floor installation. This will ascertain its compatibility with the floor finish, be it wood, carpet, vinyl or tiling. Wood, for example, can cup or warp if excessive moisture is present in the subfloor. Similarly, debonding of, or blisters can be caused in sheet vinyl.

Prepare to succeed

Prior to commencement, the presence of a suitable DPM and any underfloor heating must be established. The subfloor moisture content should be measured and if greater than 75%RH, an appropriate surface DPM specified. Before any smoothing compound is applied, the substrate must be mechanically prepared, cleaned and free from dust and debris. Surfaces which are especially friable must be consolidated with a suitable primer – either acrylic or epoxy – to avoid defects in the smoothing material and subsequent finish. Similarly, any old bituminous layers or existing adhesives must be completely removed to ensure the best possible bond is achieved with the parent substrate and provide a finished surface that is flat, even and defect-free throughout.

The use of a high-quality, self-smoothing screed is essential to ensure that subfloors can be quickly and professionally prepared and are in the correct condition to accept the chosen flooring product once dry and fully-cured. Supplied as a powder in easy to manage bags, many self-smoothing screeds are mixed with water before simply being poured or pumped onto the prepared surface. From a practicality perspective however, it is important to first identify any areas in which dips and valleys occur and ensure the smoothing screed is poured accordingly. On smaller areas, using a straight edge will identify where low points occur to allow pre-filling if necessary and ensure a flat finish. On larger projects, a level survey should be carried out to ascertain the degree of levelling required.

Working in this way, it is possible to keep waste to a minimum, which can further help to keep all important costs down. Once applied, the screed should be left to cure completely before being opened to traffic, with some screeds this can be in as little as 60 minutes. The next stage in the process is to lay the chosen flooring material. However, it’s vital to test the moisture levels in the floor to ensure it is dry enough to take the chosen flooring material. By definition, a dry reading should be below 75% RH or 2.0% CM (carbide method) moisture content by weight depending on the type of test carried out. By adhering to these simple procedures, it is possible to ensure flooring projects are error-free.

Cementitious Flooring Screed Application

Schönox® solution

To make the process as straightforward as possible, the use of specially-designed, self- smoothing screeds, primers, DPMs and adhesives such as those available from Sika Schönox®, eliminate substrate concerns whilst providing reassurance to the professional floor layer and the end user that the floor will accommodate the loading placed upon it, without adverse effects further down the line. Schönox® HS 50 is the latest addition to Sika’s H-levelling compound range. Its innovative ingredient, ActiveDry Technology, not only provides Schönox® HS 50’s fast-drying properties, it allows the screed to be pumped at an impressive thickness – from 3mm to 50mm.

As with other solutions in the range - Schönox® HS 10 and Schönox® HS 10 F, Schönox® HS 50 combines the best of both worlds; it’s a low-tension calcium sulphate-based levelling compound with the fast-drying capabilities of a cementitious system. Despite its exceptional 48-hour curing time, Schönox® HS 50 has very low shrinkage, making it the perfect base for all types of floor coverings and parquet. In terms of industry accreditation, Schönox® HS 50 is marked as EC 1PLUS R and fulfils the Blue Angel criteria for its environmentally-friendly credentials. It is also classified to EN 13813 as CA-C35-F10.

The availability of high-performance, cost-effective, self-smoothing products such as Schönox® HS 50 has helped simplify the installation process without compromise to performance. However, durable flooring requires more than first-class materials; it takes careful planning and a keen eye to scrutinise even the most minor detail to produce a surface that stands the test of time. Get the basics right, and a flawless floor is there for the making.