Form factor

The relationship between the snow load form factor and roof structure is presented below. Other roof examples and form factors are presented in the document Sriô- och vindlast BSV 97, published by Boverket.

Wind load

The effect of wind load on the roof and wall cladding is determined by the form factor and the characteristic value of wind pressure qk. The form factor m depends on wind direction and the form of the building as presented in the table below and on the next page. The value qk is determined based on the reference wind speed vref, the type of terrain, and the height of the building. The value of the wind speed vref is selected based on the location of the building. Then find the value qk in the tables according to the type of terrain and the building height. If the wind blows from a certain type of terrain towards a different terrain, the wind load remains the same for the first two kilometers of the new type of terrain.

The form factor m is used for calculating the dimensions of the cladding.

Fixing

Walls. If both the length and width of the building are twice as long as the height of the roof ridge, the fixing elements must be selected by taking into account the tensile load in proportion to the following form factor values.

General

Safety class

*If the roof panels are anchored against the lateral force according to Sheet Metal Standard StBK-N5, safety class 1 applies to all the roof panels.

Partial factors yf.

Load combinations. Load bearing capacity. Snow load + self-weight. Wind load pull – self-weight. Wind load on walls.

Deformation. Snow + self-weight. Wind load on walls. ATTENTION! m – form factor for snow and wind load, y – load reduction factor for snow load.

Deformation limits. Roof with thermal insulation. Roof without thermal insulation. Walls. The form factor is increased in shadow zones.