HouseCheck home inspectors find that builders sometimes try to cut corners by neglecting the required mechanical fixing of sections of tiled roofs. The result can be loose tiles, which can be sucked or blown out of position, thereby posing a danger to people below and also making it fairly certain that rain water will penetrate the roof in these areas.
The picture shows a Gauteng house recently inspected by HouseCheck where the builder had ignored the building regulations and a number of the roof tiles had become disloged. The result was that rain water had penetrated the tops of some of the walls, causing damp damage and cracking below. The builder, by trying to cut corners and save a few hundred rands had caused extensive and expensive damage to the structure.
Concrete tiled roofs are probably the most common type of roof covering used for new housing in South Africa. Specific regulations apply to the installation of such roofs as regards the bracing and fixing of the structural timber sub-structure, roof pitch and also mechanical tile fixing of sections of the roof.
Most of the tiles on a concrete tile roof are held in position by a combination of hooking a lug on the tile over the timber batten and the weight of the interlocking tiles. However because of wind and air pressure build-up within the roof cavity, roof tiles in exposed sections of the roof should be mechanically fixed as additional security.
The National Building Regulations stipulate that tiles along the eaves, verges and ridges of a tiled roof must be nailed and/or clipped to the timber battens to resist wind uplift. Along roof perimeters, abutments and intersections, the overhanging or abutting tiles plus two tiles in from that tile must be fixed.
Where houses are built in areas of severe weather, then three rows of tiles along the perimeter and every second tile elsewhere should be mechanically fixed. Severe conditions include locations 300m from the coast, lake shores or estuaries and crests of steep hills, ridges and escarpments. Mechanical fixing is done with serrated clout nails or with special storm clips.