General Design Criteria

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High Wind Conditions
The information presented in this catalogue is a guide for wind loading conditions. A structural engineer should be used for design purposes to ensure that spans, fixing details and roof pitches meet the requirements for the particular conditions.

Ventilation
Climatic conditions in certain parts of Southern Africa are such that condensation may occur on the underside of the roofing slates. It is therefore recommended that the space between the ceiling and the roofing slates is adequately ventilated. Purpose-made ventilating slates can be manufactured for situations where no other form of ventilation can be accommodated.

Roof Pitch
Nutec Roof Slates are designed for a minimum roof pitch of 17,5°. In high wind areas the slates may no longer provide a waterproof covering and a waterproof underlay must be installed. Refer Fig. 2, for more details. It is recommended that the pitch be increased as specified by the structural engineer or architect.

Substructure
A high standard of finish can be achieved if the supporting structure is accurate and level. Warped, twisted or poor quality battens or sagging roof trusses will reflect adversely in the finished plane of the roof. Use only well seasoned graded structural timber. To ensure that lines are true and the laps uniform, battens must be fixed exactly to the spacing specified. The batten sizes required for the various rafter/truss spacing and for the different slate sizes are given in Table 1.

Fixing Accessories
Fixing accessories in the form of galvanised and copper clout nails as well as copper disc rivets have been specially developed for Nutec Roof Slates. Full details are scheduled under Fixing Accessories.

Do not allow the use of non-approved, and often inferior, fixing accessories. EVERITE reserves its right to withdraw its guarantees if non approved fixing accessories are used.