Jim Percival, technical director at Palace Chemicals, outlines some of the issues around substrate preparation and successful fixing of thin porcelain tiles.
When carrying out any tiling, especially to walls, consideration should be given to the weight of the tiling installation and also the substrate being tiled to. According to the latest revision of the British Standard, BS 5385 Part 3: 2024 which was published in May 2024, 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.
Thin ceramic panels should be handled using specially designed equipment and by more than one person during and after removal from the manufacturer’s original packaging, as well as for the actual installation of the panels (see BS 5385 Part 3 2024 – Section 7.2.3).
The updated recommendations on tiling to plywood sheets and boards, stress the importance of using appropriate materials for direct tiling. Importantly, timber boards are no longer recommended as a substrate for direct tiling. The standard explains if timber is used as part of the build-up for flooring, it should be rigid and stable with respect to humidity and moisture changes. Part 3 notes that timber subfloors aren’t ideal substrates for floor tiling, especially where heavy static/dynamic loading is likely in service.
Timber is also not a suitable substrate for tiled floors in high humidity areas or areas which may become wet or frequently damp. There are three main categories of backerboard – lightweight foam board, which will support a maximum weight of 60kg/sqm, glass reinforced cement board, which will support 50kg/sq m and gypsum fibreboard, which is rated at 40kg/sqm.
In all cases, tilers should refer to manufacturers’ recommendations for fixing ceramic and stone lines to the board. It’s important to use only powdered tile adhesive when working with porcelain tiles, as a powdered adhesive will create the strongest bond, given that porcelain tiles are impervious and have different characteristics to a ceramic tile.
Most cement-based tile adhesives will work well for porcelain tiles, but an S1 adhesive provides an element of deformability which is preferable especially for flooring installations or any projects where there may be vibration. Remember the tile adhesive itself adds weight to the installation. An S1 tile adhesive can add an additional 2.3kg/sqm.
This is one of the advantages of the new generation of lightweight tile adhesives which, in the case of Palace Chemicals’ Extra-Lite for instance, adds just 1.3kg/sqm. To reduce the weight of tiled installations and also to be more economical and sustainable at the manufacturing stage, manufacturers have developed a new generation of thin porcelain tiles, which can vary from 3mm to 5.5mm in thickness.
Tilers should always refer to manufacturers’ recommendations regarding fixing thin porcelain tiles. These are attractive and very hardwearing. Because of their reduced thickness, they’re also ideal for refurbishment works when tiling over existing materials, provided a suitable primer is used, as they don’t add as much bulk to the installation as thicker tiles.
Being lighter, they’re also easier to install in certain locations, such as tight corners. However, although they can be as strong as other tile types, care should be taken to ensure the substrate, whether wall or floor, is level. As they say, it doesn’t matter how good the tile adhesive is, the tile itself won’t bend.
There’s a classification for surface regularity set out in British Standards, which should be adhered to for all tiling, but is particularly important when working with thin porcelain tiles. It’s divided into SR1, SR2 and SR3. This is measured by placing a two-metre straight edge on the surface and measuring any gaps underneath with a slip gauge. SR1 is the highest standard and allows for a maximum gap at any point of 3mm. SR2 is the normal standard and allows for a maximum of 5mm, while SR3 is known as the utility standard and allows for gaps of 10mm.
If these steps are followed, the ease of handling, space-saving and aesthetic benefits of thin porcelain tiles can be enjoyed in the home or commercial environment.
01513 369104
sales@palacechemicals.co.uk
www.palacechemicals.co.uk
