Tiles are coverings that hold up well to the roof and resist wind gusts. Provided they are properly installed and fixed. Tile installation: tips from the roofer.
Under the influence of strong gusts the tiles rattle and click, but they stay in place. However, there are strong gusts which can pull out individual pieces and drop one, several or even more than a dozen tiles. Every now and then we hear of roofs being torn off or tiles falling off during storms. It often happens due to execution errors made at the stage of roofing works. We advise how to fix roof tiles properly.
Tile installation: which fixing method is best?
Each material has different requirements as to the method and number of fixing points. There are many models of tiles and equivalent forms of fixing, and the contractors’ approach to this issue is also different – from fixing all elements of the roofing to laying completely without fixing. It is also difficult to clearly indicate which model of tile installation is the best. Most often 3 to 4 tiles per 1 m2 are fixed on the slope, which means that out of 10-12 tiles per 1 m2 most of them are held in place.
It has to be remembered that the double straight pin (the most commonly used fixing element) holds one overlap knot, i.e. 3 tiles. The installation consists of catching two vertically adjacent tiles (top and bottom) by the side lock. The third tile clips into the zipper and is held in place by the two fixed pegs.
Before fixing the tiles always read the manufacturer’s instructions and the designer’s guidelines which should contain information about minimum number of fixing points (number of brackets per 1 m2 of coverage). The designer, taking into account roof slope inclination angle and the wind zone in which the investment is located, also determines what accessories for installation of tiles will be needed. Apart from these guidelines, an experienced contractor also takes into account the shape of the terrain and the form of the neighbouring buildings. Often there are so-called ‘air chimneys’ on the boundary of forests or in the vicinity of multi-storey buildings, where the wind speed and force are significantly higher than in the rest of the area. An unusual location, e.g. in the mountains, should also prompt the roofer to fix the tiles firmly.
Manufacturers’ instructions always state the minimum number of recommended fixing points. If there is even the slightest doubt, the number of fixing points should be increased and the covering reinforced.
General rules of tile fixing
In the absence of detailed installation instructions for a given tile model, some generally accepted rules for fixing tiles should be taken into account. On roofs with pitches over 65º (e.g. mansard roofs) all tiles should be fixed. In practice we fix all of them except for those which we sometimes have to take off, to facilitate communication during work on the roof.
We always fix all gable tiles, plinth tiles, tiles located above guttering, by chimneys and roof windows. Also fix all cut tiles, especially those in valleys and ridges. Additionally, tiles exposed to hanging should be fixed, e.g. tiles which have had their locks removed or filed down in order to fix roof communication supports or lightning conductor installations. Particular attention shall be paid to gable tiles and ridge tiles. All elements shall be fixed there.
Tiles are laid from right to left, so if the house is situated in the direction of prevailing winds, one slope will slip and the other will be set “upside down”. Therefore, it is also advisable to increase the number of tile fixings on those roof slopes which are laid against the direction of the prevailing winds, i.e. in such a way that the wind presses under them.
Accessories for fixing tiles
There are many accessories, all of which allow the tiles to move slightly. Nails and screws are used to fix the tiles or special clips or clamps are used. Tile and roofing accessories manufacturers offer many (several hundred) models of fasteners for tiles, e.g. universal straight double clips, single clips, eaves or storm clips and special clips designed for particular models of tiles and for untypical applications, e.g. clips for cut tiles. Some clips for battens are adjusted to the height of the battens, others are driven into the battens. Those for cut tiles are slipped over the side of the cut piece and fixed with screws.
Most models of clay roof tiles and some concrete roof tiles have factory-made holes into which screws or nails can be driven. Gable tiles and ridge elements are screwed in. Roof tiles with slopes (e.g. plain tiles) are fixed with nails, because unlike screws the nails can be removed, which makes it possible to replace the damaged part.