How to count roof bias

How to count roof bias

Calculation of bias of roof – important stage of construction jobs. Not only constructional features of roof, but also the roofing material used for its construction depend on bias of roof.


1. When calculating tilt angle of roof consider weather conditions of the region in which construction is carried out. Than more warmly and the land on the street, especially flat there can be built roof. The more abruptly the tilt angle, the less on roof will accumulate snow, so, the snow load is minimized. At the same time, with increase in tilt angle of roof wind pressure upon roof therefore it is not recommended to build such design in the area with constant strong winds increases. The tilt angle of roof can fluctuate from 10 to 60 degrees.

2. Pay attention that with increase in tilt angle of roof the roof cost increases. For example, at construction of roof with tilt angle in 60 degrees its cost exceeds the cost of flat roof twice if tilt angle of roof 450, then the cost of such roof is one and a half times more than the cost of flat roof.

3. Calculate corner of slope of roof as the relation between height of the fad of roof and half of underlay.

4. You remember: the bias in the valley gutter has to be not less than 1%. If the bias of roof is less than 10% and this roof is made of rolled bituminous and polymeric or bituminous materials, for protection of top layer surely lay protective layer from gravel or pebble gravel. At the same time, thickness of protective layer has to be 10-15 mm of gravel, and pebble gravel – from 3 to 5 mm. If the roof is built from corrugated asbestos sheets or metal tile or metal professional flooring, then splice closure between floorings has to be surely executed.

5. When calculating tilt angle of roof consider the fact that the way of withdrawal of melt and rain waters, in addition, will depend on the rated size received by you. The drainage system can be unorganized (external) and organized (internal and external).

Author: «MirrorInfo» Dream Team