As the season for external tiling approaches, Jim Percival, technical director at Palace Chemicals, says that tile fixers need to be aware of a number of key factors which can influence the success or otherwise of their tiling job. Chief amongst these is familiarity with the latest updates to British Standards as they affect tiling.
In May 2024, a new Part 3 was added to BS5385, the British Standard for Wall & Floor Tiling. This brought in a number of changes, including the provision that, when direct tiling on to plywood and other wood-based sheets or boards, an intermediate layer, such as an uncoupling membrane, reinforced tanking system or tile backer board should be used.
It also brought in a new provision relating to external tile installations, stating that intermediate movement joints should be incorporated within the tile assembly at intervals between 3m and 5m. This is because exposure to greater fluctuations of thermal and moisture movement is likely to be encountered in external tiling installations.
The Standard explains that, depending upon the positioning of the installation (amount of exposure to sunlight and heat), anticipated movement in the substrate, the size, shade of colour and format of the tiles or slabs selected and the width of the tile joints, further reductions in the distances between intermediate movement joints should be taken into account.
All joints between porcelain tiles should be grouted with a suitable proprietary grout conforming to BS EN 13888 i.e. minimum CG2 or RG type grout.
It is also worth being aware that the Standard stresses the importance of the quality of workmanship and requires that the installation of ceramic or natural stone tiling is carried out with ‘efficient supervision and the employment of trained operatives, skilled to an appropriate level of competence certified by a recognised authoritative body, e.g. The Tile Association’.
When it comes to external tiling, it is now a well-established trend for homeowners to maximise the outside space available to them around their homes. The usability of exterior areas ranks as a key factor influencing purchase decisions in the housing market currently, and the trend is also reflected in the commercial market, as the hospitality sector in particular seeks to make the most of any external space that is available to them.
Often external areas are tiled using 20mm porcelain tiles or natural stone, which enable design themes to be created which either complement or contrast with tiled surfaces installed internally in buildings. The continuation of internal design themes to the exterior of a building is an important trend, leading to a blending of internal and external space.
There are plenty of tiles and natural stone products on today’s market, which will do an excellent job in external locations. Problems however can arise at the installation stage. Often these jobs are done by builders or keen DIYers, rather than by experienced and knowledgeable tile fixers or landscapers. This can lead to problems if correct procedures (especially with regard to preparation of the substrate) are not followed.
A landscaper will take a different approach to this issue, compared to a tiler. A landscaper will not normally want to create a concrete base for laying the tiles. He or she would begin by evaluating the designated area to determine its suitability – ensuring the ground is level and free of any loose debris, vegetation, or standing water that may interfere with the installation. If necessary, the area will be excavated to a depth of around 150 – 200mm to create a stable base and fully remove any existing materials such as grass, soil or old paving to enable a solid foundation for the tiles. On to this a compacted Type 1 (MOT) base can be laid.
Once the sub-base is prepared and fully compacted, the next stage is to lay a permeable bedding mortar to a suitable depth. This will allow any water or moisture to pass through the installation freely and drain away.
A tiler, on the other hand, would want to work on a concrete substrate and would use a flexible adhesive, bearing in mind the maximum bed depth of the individual adhesives, using a 20mm round notched trowel to fix the 20mm porcelain tiles.
Both types of installation would require the use of a priming slurry to ensure a good bond between the tiles and the appropriate adhesive. After drying, they would be grouted in the colour and type of grout of the customer’s choosing.
Consideration also needs to be given to correct cleaning regimes, in order to maintain both the aesthetic appearance and the required slip performance. External tiled or stone finishes are likely to become contaminated more quickly from dirt and debris. High pressure washing is therefore often employed. Although this will not damage the tiles themselves, it may cause damage within the grout lines so should be carried out with care. Consideration should also be given to the use of a proprietary impregnating sealer and a bespoke tile cleaner.
www.palacechemicals.co.uk
