Roofing Quote Footage is Not the Same as Home Square Footage
Depending on where the information is coming from is going to determine the basis on which the estimated roof footage is calculated. The roof square footage is what we (roofing contractor) need to calculate a budget quote to do the job.
Measuring the Roof’s Pitch
The incline or pitch of a roof can be easily measured with a level, tape measure, and a pencil. The roof’s pitch is the number of inches the roof rises in 12 inches. Therefore, mark off 12 inches on the level and place it down horizontally against the roof rafter.
Next, measure vertically from the 12-inch mark on the level straight up to the underside of the rafter, as illustrated below. That measurement is the number of inches the roof rises in 12 inches.
Some homes will have roofs with multiple pitches. Porches and dormer windows, for example, can have a different pitch from that of the rest of the house. For an accurate surface area measurement you should make note of these additional structures.
Using the table below, lookup the pitch/es and make a note of the number/s in the multiplier column.
How to use the google maps area calculator tool to measure a roof
Special precautions must be taken when measuring the area of a roof. The images that appear on google maps are often at a slight angle, which combined with the angle of a roof can cause errors. For this reason it is best to outline the roof at points which are all at the same elevation. On a simple house for instance you would only click on the corners of the roof and not on any points along the peak as that would cause an error. After measuring the area of the footprint you can estimate the actual roof area based on the angle of the roof. Similarly if you using the area calculator tool to measure a roof with multiple levels, you should do the individual section separately. The google maps area calculator is not 100% accurate. Do not rely on this tool as your only resource in making important decisions.