|Carpentry for Vocational Schools - A Teacher's handbook (GTZ, 252 p.)|
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.
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.