IMPORTANT CHANGES TO BRITISH STANDARDS

As per the standard five-year review of British Standards and changes within the tiling industry since 2009, the British Standards 5385 Part 1: 2018 has been published. This revised version introduces a significant change: exclusion of plywood as a background material for direct fixing of ceramic wall and natural stone tiles. In this article, we will discuss the reasons behind this exclusion and other changes made in the British Standards.

Exclusion of Plywood

The new standard replaces Clause 6.1.2.7 Other sheets and boards (see also 6.2.3.3) and prohibits the use of sheets or boards that are subject to movement from changes in moisture content. Moreover, plywood and other wood-based sheets or boards cannot be used for direct tiling. The reason behind this exclusion is a significant uplift in the use of tile backer boards like BAL Board. Additionally, a variation in plywood quality available in the market provided a solid case for its removal from the British Standards.

Furthermore, while high-quality external grade plywood is still available, it is more expensive. Previously, BS5385 Part 1: 2009 acknowledged that tiling direct to plywood was possible, providing it was limited to small areas and installed in a way that they provide a dimensionally stable and rigid background. However, the quality of plywood for tiling purposes has decreased significantly with cheaper imports flooding the market.

Wood is a hygroscopic material, which means that its moisture content will change based on any changes in the environmental conditions on site. Hence, the dimensional stability of wood-based boards cannot be assured, and there is always a risk of installing ceramic or natural stone tiles onto plywood or other wood-based sheets.

Weight Restrictions

Another technical consideration for wall tiling is weight restrictions. Plywood is deemed to have a maximum weight of tiling per m² of 30 kg compared to proprietary tile backing boards, which generally can support heavier weights per m² of tiling, as per table 3 of BS 5385-1: 2018 and the TTA Internal Ceramic Tiling to Sheets and Board Substrates document 2016. A competitive tile backing board market makes the prices more attractive to tile fixers and contractors. This combined with additional features and benefits of providing a background for tiling, which is dimensionally stable and resistant to moisture and thermal movement.

Structural Use of Plywood

While plywood is not recommended as a background for direct wall tiling, it can still be used as a structural board when overlaid with a suitable tile backing board, particularly where installation of mechanical fixings is required, e.g., for mesh-backed natural stone where it is not possible to remove 75% or of the mesh backing.

Changes to Other British Standards

Apart from the exclusion of plywood, other changes have been made in British Standards 5385-1: 2018. Previously, in internal dry wall areas, it was recommended that tile adhesive should cover a minimum of 50% coverage spread evenly over the back of the tile. However, with the increase in size and types of tiles, i.e., larger formats and thin ceramic panels, BS 5385-1: 2018 now advises that tiles with a surface area of less than 0.1 m², but which weigh more per square meter than 70% of the background’s capacity to carry the weight, should be solidly bedded.

Included within the scope of British Standards 5385-1: 2018 are large format ceramic tiles, ceramic panels i.e. tiles with a surface area >1m² (any edge length >1200 mm) and thin tiles i.e. ceramic tiles and panels.

The British Standards 5385-1: 2018 also outlines the importance of proper preparation of surfaces to receive tiles or natural stone. The standard emphasizes the need to ensure that surfaces are clean, sound, and free from contamination, which could affect the bond strength of the adhesive. Any previously applied coatings, paint, or other substances should be removed before the tiling process starts.

The standard also recommends that any necessary repairs or alterations to the background structure should be completed before tiling begins, and that any floor heating systems or other service penetrations should be in place before the tiles are laid.

When it comes to selecting the right adhesive, British Standards 5385-1: 2018 outlines the importance of choosing an adhesive that is suitable for the specific application, taking into account factors such as the type of tile or natural stone, the background material, and the location of the installation.

By adhering to the guidelines outlined in British Standards 5385-1: 2018, tilers and contractors can ensure that their installations meet the highest standards of quality and durability. Adhering to these standards can also help to prevent costly mistakes and avoid the need for costly repairs in the future.

In conclusion, British Standards 5385-1: 2018 represents a significant update to the previous standard and reflects changes within the tiling industry over the past decade. The removal of plywood as a background material for direct fixing of ceramic wall and natural stone tiles and the inclusion of new recommendations for large format tiles and thin ceramic panels are just a few examples of the changes made.

By following these standards, tilers and contractors can ensure that their installations meet the highest levels of quality and durability, helping to prevent costly mistakes and ensure the long-term success of their projects.