If your goal is to only calculate the roof height do not enter any numbers in wall height field and only use building width and roof pitch fields.
Height of roof feet.
You will need to express this size in terms of square feet.
The first step in a free roofing estimate is measuring the roof dimensions.
Common rafter elevation if you are calculating rafter length from the center of the ridge beam as shown below you will need to subtract half of the thickness of the ridge beam from the top end of the rafter.
For example if the roof rises 4 feet and the span is 16 feet twice the run then the pitch is 4 16 or 1 4.
Carpenters measure roof pitch as inches of rise per 12 inches of run.
A 1 in 12 roof pitch roof rises 1 inch for every 12 inches of run.
Rafters are nailed to the ridge board and run down to overhang the exterior wall.
This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement.
The pitch of a roof determines the height of the ridge board that runs the length of the house.
For example if the peak is 4 feet and the total roof with is 20 feet the total rise is 4 feet or 48 inches.
The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7.