Roof: pitch, degrees, sloping length and area
Find the roof pitch in percent and degrees, the sloping length from eave to ridge and the total area of the roof surfaces from three measurements.
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One house, four questions
The example is a symmetrical gable roof. The house is 8 m wide, and the roof is 10 m long. The horizontal run from eave to ridge is therefore 4 m, and the ridge is 3 m above the eave.
The pitch is 100 × 3 / 4 = 75%. The angle is arctan(3 / 4), about 36.87°. The sloping length is √(4² + 3²) = 5 m. Two roof surfaces of 10 × 5 m give 100 m².
The floor plan of the house is 8 × 10 = 80 m². The roof surface is larger because it slopes. So do not use the floor plan as the roof area.
Measure from the right points
The horizontal run is measured horizontally from the eave in under the ridge, not along the roof surface. On a symmetrical gable roof, it is half of the full width. The height is measured vertically from the same eave up to the ridge.
Overhangs must either be included in your measurements or added afterwards. Do not count them twice.
The different roof shapes
A shed roof has one sloping surface. A symmetrical gable roof has two identical surfaces, so the area of one surface is multiplied by two. If the sides differ, calculate each one separately with the Shed roof option.
Hip roofs, dormers and extensions are divided into trapezoids, triangles and rectangles that you calculate separately, for example with the area calculator. The number of roof tiles, sheets or rolls depends on the product's coverage and overlap and is not included here.
Other calculators for the roof
If you know the angle or the pitch in percent, Slope and degrees can convert it and find the height from the horizontal run. If you need another side of a right triangle, use Pythagorean theorem. You can calculate the insulation under the roof with insulation volume.