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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

13.3. Rafter and ridge roof

The rafter and ridge roof is used when the span is short or where high ceilings are desired or where rooms have been included in the design of the roof.

a) Technical terms:

- The rise: The rise is the high of the roof.

- The span: The span is the width of the roof at the base of the roof pitch triangle.

- The run: The run is half the span.

- The overhang: The overhang is the distance between the outside wall and the end of the roof, which is parallel to the wall.

- The roof pitch triangle: The roof pitch triangle is the slope of the roof and is expressed in degrees.

- The birdsmouth: An angle cut on the edge of a piece of timber so that it sits on the angle of a cross piece. Used at the foot of a rafter, where it sits on the top plate.


Figure


Figure

b) Strenghtening the rafter and ridge roof: - If the span of the roof is up to 5 m, it has to be strenghted. It is done with a COLLAR-TIE or TIE-BEAM.


Figure


Figure