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T he following gives an overview of procedures and methods used.For more detailed technical information please click here to download a copy of "A Guide to Good Thatching Practice" (38 pages) This is a practical reference work for both lay persons and building professionals for the sound design, construction and maintenance of thatched roofs. The guide deals with thatching materials, describing the different naturally occurring grasses and reeds, the tools of the trade, construction techniques and workmanship. Lightning protection and fire safety of thatched roofs are treated specifically and appendices offer a typical thatch roof specification and set an approach to the rational fire design of thatched lapas. MAINTENANCE All Letaba roofs are maintained for a period of 5 years free of charge - storm damage excluded. After that it should be serviced at approximately 10/12 year intervals. At the end of the original roof's life span of 35 years a new layer of 70 to 100 mm can be thatched over the existing roof. DURABILITY Conservatively 35 years. CAD DESIGN Letaba Thatchers uses a state of the art software called Caddie to design plans to suit the requirements of clients. Please contact our in-house designer for more information. We have an A0 HP Plotter at our head office and all designs and structures are thoroughly checked and approved before work proceeds.
THATCHING METHOD The thatching grass is compacted evenly and the density of the thatch is a minimum of 30 kg on a minimum of 150 mm thick cover. The thatching is compacted and held in position by a reed-like element above and a batten below. These are stitched together with treated twine. THATCHING GRASS Hyparhenia species hand-cut during the cutting season. Grass is cut above the first notch and only straight pieces are used. Grass length differs from 760 mm to 1500 mm and the thicker ends range from 1,8 mm to 4 mm Spray thatch (ceiling grass) is well combed and cleaned from all loose leaves, etc. Cape thatching reed is also used if requested. BODY MOISTURE 7-12% by weight. COLOUR The thatching grass is of beige/yellow colour during construction and darkens in colour during the rainy season. FIBREGLASS RIDGES The ridges are made of fibreglass in Letaba Thatchers' own factory. These ridges are renowned for appearance and durability. CEMENT RIDGES The ridges are constructed of cement, bird mesh and waterproofing material. These ridges are renowned for durability. THATCH RIDGES The ridges are made of thatching grass and are mostly for aesthetic appeal, but are not as durable as cement. ROOF STRUCTURE Roof rafters are spaced at a maximum of 700 mm centres. All joints in rafters and trusses are spiked with 150 mm to 200 mm wire nails and bolted at the main stress points (main tie beams, collar ties, scissor braces, ceiling joists, etc.). Bolt sizes differ from. 12 mm to 24 mm in diameter depending on the size of the roof. On roof spans of up to 9 m the rafters must be a minimum diameter of 75-100 mm at the thin ends. Roof spans of 9 m and larger will use 100 mm to 250 mm diameter poles (measured at the thin end) depending on the width of the building. The battens range between 20 mm-40 mm in diameter and lengths not shorter than 3 m. The battens (laths) are spiked to the rafters with 75 mm wire nails. The battens (laths) are spiked as follows. Starting from the eve (bottom) the first three laths should be 150 mm apart. Thereafter it is spaced at 270-300 mm centres right up to the top of the roof.
South Africa :
International : Email : letaba@letabathatchers.com P.O. Box 260
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© 2003 Letaba Thatchers