Unexpected consequences of the introduction of BS 5534 2014

John Mercer, technical manager, SandtoftDue to the great PR, training and presentations from all sides of the roofing industry, everyone must surely now be aware of the newly published revised BS 5534: 2014 British Standard for Slating and Tiling, which was introduced last September and came into full force March 1 this year.

However, we are now starting to face a few, perhaps unexpected, consequences of the changes in the new Standard, and I thought it would be interesting to devote this article to one of these, as it is creating great debate within the roofing world at the moment; i.e. just how does a roofer mechanically fix an individual roof tile when all surrounding tiles are already fully fixed?

Firstly, let us examine why this problem now arises. The new Standard requires that all single lap clay and concrete roof tiles be mechanically fixed; i.e. by nailing, clipping or screwing, or a combination of any of these methods. In the days when it was common to have unfixed single lap tiles, it was possible for the roofer to leave out individual tiles, or push tiles up under the course above, to leave battens exposed for walking on as access over the completed tiling. Once the roof work was completed, the missing tiles could be inserted or pulled back into position. These tiles would hang on the battens but would not be mechanically fixed. 

Now that all tiles must be fixed, this inability to remove or push up tiles leads to the risk of tiles being broken through foot traffic. This leads me to my first point and one that I have dealt with in detail in previous articles; roofers must take care to avoid damaging the tiles through foot traffic by either finding smarter ways of progressing the tiling work, or using equipment such as work boards, roof ladders etc. to protect the laid tiles.

But, assuming tiles have broken and need replacing, just how can the roofer secure the replacement tiles? Unfortunately, it is not possible to fix a single tile within an existing array using the normal methods of a nail / screw through the nail hole, or by clipping at the tile. In their efforts to provide solutions to this that fully comply with the requirements of BS 5534, tile manufacturers issue method statements describing different solutions to install individual, mechanically fixed tiles. These generally involve drilling the replacement tile through its lower portion in order to provide a screw or nail fixing into the timber structure below. Of course, this is not ideal because the fixing remains visible and also introduces the risk of water ingress through the exposed nail hole, either immediately or over time if the seal degrades through UV exposure and weathering.

Adhesive: “in the spirit of the Standard”
Therefore, I want to suggest an alternative fixing method; adhesive. This may not fully comply with the Standard’s requirements for a full mechanical fix; i.e. with the ?letter’ of the Standard, but I feel that it is certainly in the ?spirit’ of the Standard. Wienerberger has many years of experience in the use of adhesives for roofing materials, for use both in factory conditions and on site. Indeed, the Standard now recognises the use of adhesives on site, albeit in combination with mechanical fixings.

It is important that all surrounding tiles be fully mechanically fixed. It’s normally possible to remove a single damaged tile without disturbing the surrounding tiles or their fixings. Generally, if an array of two or more tiles required replacing mid-roof, all but the last tile can be mechanically fixed, so the use of adhesive is only ever required for a single, isolated tile.

The use of adhesive to secure a single tile to its neighbouring tiles means that the wind load on the bo