A roof s pitch is determined by how much it rises vertically for every foot it runs horizontally.
Roof area formula.
Dividing by 12 gives the ratio of inches in rise per distance.
Roof angle is the value in the user defined.
Roof pitch is given as the number of inches in height change over the distance of one foot.
Thus a moderate 6 in 12 roof pitch means that the roof rises 6 inches vertically for every 12 horizontal inches it runs.
The roof area is calculated.
You may want to hide the display of the area value in the plan view to avoid confusion.
Select the area measure.
Multiply your house length by your house width to get the area.
We used this detail to calibrate our folding carpenter s rule scale for reading roof slope from the ground.
Area cos roof angle pi 180 area is the value of the area measurement.
To accurately calculate the area of your roof you must first determine its slope or pitch.
Divide your roof pitch by 12.
For example 40 feet x 30 feet 1 200 square feet next multiply the area by your roof s pitch.
Right click on the area measure then click properties.
Measure the length of the rafters from the peak to the lower edge.
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.
6 calculate the total surface area of the roof using the following formula.
In the construction industry roofs are measured in squares one square equals 100 square feet.
The answer to this is the total number of squares on your roof for which you need to purchase shingles.
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.
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Explanation of the formula.
The roof area is simply 114x18x2 plus 30x18x2 giving 5184 square feet which is perfectly adequate for estimating materials.
Divide the area you calculated in step 4 by 100.
Details of that procedure are at roof measurements.
Tan 45o 1 00.