Thatch Galore

Construction

TIMBER REQUIREMENTS

Timber poles must comply with the requirements of SANS 457-2 or SANS 457-3, as relevant. Laths and battens must comply with the requirements of SANS 1288, 1707-2 (eucalyptus), or SANS 1783-4 (pine), as relevant. All timber should be preservative treated in accordance with the requirements of SANS 10005.

Poles for use as structural elements shall have a diameter of at least 100 mm measured at thin ends. PLANTING POSTS

The science of treating timber properly provides for the preservative to be deeply impregnated into the sapwood thereby giving a deep envelope of treatment around the central heartwood. All poles must be CCA treated and meet the SABS 457 Specification for Eucalyptus and Pine wood. Strict attention is given to SABS 0163:1994 Sections 1 and 2, Table 5 dealing with tensions for round poles.
Besides the quality requirements of Code 457, the poles must also meet aesthetic requirements, namely no excessive cracks or crookedness, and they must be clean.
LATHS
Laths must also meet the SABS 457 Specification and must be of the Eucalyptus species and must be reasonably straight.
ROOF CONSTRUCTION
All roof trussed must be made in accordance with the details and design of a thatch roof specialist or engineer. Drawings should be available.
All carpentry work must be neat and finished off to a high standard.
Roof construction must slope at 45° with a minimum slope of 35° over attic/dormer windows.
Trusses must be spaced at a maximum of 700-800 mm apart.
The minimum eave overhang is 400mm from end of pole to wall.
The minimum poles diameter is 75-100mm up to a length of 9 m. A larger diameter must be used on longer poles.
In a span of less than 10m, all load points must be fastened with 12mm bolts, and with 16mm bolts on larger structures.
Anti-split plates of the correct size must be affixed to all sawn off pole ends.
There must be a minimum spacing of 150mm between the first and last three laths, and 300mm between the remainder. The laths must be secured with 75-100 mm nails to every truss.
A proper truss plan must be designed to carry a minimum weight of 70 kg/m2

""