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close this bookCarpentry for Vocational Schools - A Teacher's handbook (GTZ, 252 p.)
close this folder13. ROOFING
View the document(introduction...)
View the document13.1. Different roof shapes
View the document13.2. Technical terms of a roof
View the document13.3. Rafter and ridge roof
View the document13.4. Roof truss
View the document13.5. Diagonal roof bracing
View the document13.6. Roofing iron
View the document13.7. Laying of roofing iron
View the document13.8. Finishing a roof

13.6. Roofing iron

Roofing iron is corrugated for many reasons. It is stronger and more able to withstand load than flat sheets. The corrugations also give definite ware channels and serve to gauge the side lap of the sheets, and when nailed through the crown lines of the roof are more waterproof.


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a) Space the Purlin or Batten: - For corrugated roofing iron use battens with a size of 75 mm x 38 mm minimum. Place one batten near the ridge so that the ridging can be nailed to it and the bottom batten so that its top edge is in line with the plumb-cut of the rafter feet. The remainder are spaced in between.

The battens should be set at a distance of 1200 mm to 1400 mm. The distance should not exceed 1400 mm.

NOTE: If there are two or more rows of roofing irons, the overlap should be approximately 300 mm.


Figure

b) Fastening corrugated roofing iron: - The most effective way of fastening corrugated iron is by means of roofing screws and washers. Cheaper fixing methods are the spring-head plain nail, the twisted shank nail or the springhead screw. Holes should first be made with a brick punch which must be kept sharp to prevent denting of the corrugations .


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