|FCR: Fibre Concrete Roofing (SKAT, 1987, 185 p.)|
- It ist not possible to consider the FC technology in isolation of the roof structure.
- Most damages to FC products on roofs can be tracked down to faults in the roof structure and in the way the products were placed and fixed.
- The smaller the element, the more easily it adapts to the structure.
- The tile presents several advantages over the sheet, but usually needs imported equipment and electricity. On the other hand there is still room for improvement of the sheet technology.
- The design should be simple, e.g. gable roof with rafters and purling, or prefabricated trusses and purling. Minimum pitch of 20°, but up to 30° is required in areas where torrential driving rain occurs. Imposed loads, especially wind suction, may produce higher forces than self weight.
- Good quality timber is desirable but wood is getting scarce and expensive.
- FC tiles need approximately the same quantity of timber as FC sheets.
- Craftsmanship: Carpenters who traditionally build roofs for C.I. sheets will need special training to achieve a more demanding qualify execution. Purlins and tile laths must be straigt and parallel. FCR elements, particularly sheets, cannot adapt to inaccuracies of supports without risk of cracking.
Installation of roof cover
- Prior to installation on roof, check FC elements for good quality, exact size, properly fitting overlaps, correctly formed mitres, etc. The laying of sheets should preferably be done by a team of carpenters and sheetmakers. Edges and overlaps should be well aligned. The installation of the ridge tiles requires careful attention too.
- Sheets should be handled with great care.
- Fixing: the driving of nails through elements should be discouraged. If screws or J-hook bolts are used they must not be overtightened. Cast-in wire loops which allow fixing from underneath prove to be the best solution so far. Sheets should rest on both purlin and bottom sheet at each corrugation.
TREAT FC PRODUCTS LIKE CLAY TILES! NEVER GO ONTO A ROOF WITHOUT CRAWLING BOARDS!