The fixing pattern outlines the area of tiles in the roof areas that require securing. If clipping is needed and the appropriate storm clip is determined by means of a wind uplift calculation, the tiles should not be secured randomly. The entire roof area must be considered to achieve the best possible protection. This is achieved by clipping each tile, or every second or third tile in a row (and all rows are offset diagonally), accordingly to the calculated laying pattern.
Tests have indicated that, in most cases, the clipping of every second tile with a sidelock clip produces considerably better results than if the head of each tile is mechanically fixed.
In special cases, the layout pattern will need to be customised to accommodate specific roofing materials.
Mortar bedding without mechanically fixing the tile will not provide the required wind uplift protection.
Regulations for securing tiles, slates, shingles and shakes may vary from country to country following the National Annex of EN 1991-1-4/NA.