Roof Area Formula

We used this detail to calibrate our folding carpenter s rule scale for reading roof slope from the ground.

Roof area formula. Divide your roof pitch by 12. Which is the same as saying a 45 degree slope a 12 in 12 slope or the roof will rise 12 for every 12 of horizontal run. The roof area is simply 114x18x2 plus 30x18x2 giving 5184 square feet which is perfectly adequate for estimating materials. 1 200 x 1 05 1 260 square feet to allow for hips ridges and waste add 10 of your final number for a gable roof and 17 of your final number for a cottage roof.

6 calculate the total surface area of the roof using the following formula. Measure the length of the rafters from the peak to the lower edge. Double click in the roof angle column of the area measurement type the roof angle and press enter. Roof angle is the value in the user defined.

Multiply your house length by your house width to get the area. Right click on the area measure then click properties. You may want to hide the display of the area value in the plan view to avoid confusion. For example 40 feet x 30 feet 1 200 square feet next multiply the area by your roof s pitch.

Tan 45o 1 00. Explanation of the formula. Thus a moderate 6 in 12 roof pitch means that the roof rises 6 inches vertically for every 12 horizontal inches it runs. Clear the show caption check box.

In the construction industry roofs are measured in squares one square equals 100 square feet. A roof s pitch is determined by how much it rises vertically for every foot it runs horizontally. The answer to this is the total number of squares on your roof for which you need to purchase shingles. Details of that procedure are at roof measurements.

Select the area measure. Area cos roof angle pi 180 area is the value of the area measurement. The roof area is calculated. Dividing by 12 gives the ratio of inches in rise per distance.

Roof pitch is given as the number of inches in height change over the distance of one foot. The roof area for a hip end is the same as for a gable end the intersection is equivalent to a hip slightly conservative so there is usually no need to consider triangles when measuring a roof.