In this article, we will talk about calculating the roof surface starting from
- Roof incline
- House surface
(plus the area with which the roof extends outside the house - it can be calculated by multiplying the extension with the perimeter of the house).
How to calculate Roof surface
For a roof incline of (pitch x/12):
We find the slope factor from pitch:
Slope factor = (hypothenuse of rise 4 and run 12) / 12
Hypothenuse is therefor squared root of 160:
hypothenuse = root of
Slope factor is hypothenuse divided by 12:
slope factor = 12.65 / 12 =
Surface of the roof = house surface x slope factor:
x 1.0541 =
This formula for calculating the roof surface produces approximate results!
The resulted surface area is similar with that of a gabled roof, but other roof shapes might have a very different surface area!
One advantage of this formula is that it can be used as an approximation for houses with unique shapes or with complicated roofs - we can use it to obtain a very general idea about the roof surface.
Please check our roof shape calculators - if we have a calculator for your roof shape, it is going to produce pretty accurate results.