# Calculate the Roof Angle – Roof Pitch

The inclination is the slope or the steepness of a roof surface . It is usually expressed as an angle in degrees , sometimes in percent , but rarely as a number. Depending on the roof pitch , roofs are referred to as flat roofs , flat roofs or steil roofs . In building plans , in addition to stipulations on the prescribed roof form, there are often also those on the roof pitch.

## Calculation

The roof pitch is obtained from the height (= vertical distance from the roof ridge to the eaves ) and a standard size of up to the roof ridge (= horizontal distance from the roof ridge to the eaves). The angle of inclination can be calculated very easily using the arc tangent:

• {\ Displaystyle \ arctan \ left ({\ text {roof height}} / {\ text { (On the pocket calculator the arcustangens function is mostly as {\ Displaystyle \ tan ^ {- 1}} , The angle being expressed in degrees , rad or gon according to the DRG setting)

When converting an angle as a percentage, the following formulas help, but bear in mind that a 100% slope is an angle of inclination of 45 degrees:

• Of an angle in percent: {\ Displaystyle 100 \ times \ tan \ alpha = x \%} • Of percent into an angle: {\ Displaystyle \ arctan \ left (x \% / 100 \ right) = \ alpha} ## Building Constructions

The roof inclination has an influence on the type of roof covering , since certain systems are only suitable for a defined inclination range.

The lower the roof pitch, the greater the risk that driving rain or snow will get under the roof and damage the roof . For this reason, the roof pitch of buildings in cold countries with snowfall is greater than in warm countries. But also the choice of the roofing has an influence on the rain safety. Roofing tiles, for example, protect the roof from rain damage because the precipitates are conducted from the higher, overlapping roof tile to the underlying floor so that the water can not penetrate into the substructure. Likewise, with low inclinations, the self-cleaning effect of the roofing is endangered and the risk of flooding is increased.