Roof Estimating Formulas

Steep slope roof pitch of 12 or 45 degrees.

Roof estimating formulas. A roof s pitch is determined by how much it rises vertically for every foot it runs horizontally. 1 roof square 100 square feet. In the united states a run of 12 inches 1 foot is used and pitch is measured as the rise of the roof over 12 inches. Thus a moderate 6 in 12 roof pitch means that the roof rises 6 inches vertically for every 12 horizontal inches it runs.

Roof pitch roof pitch is the measurement of a roof s vertical rise divided by its horizontal run. Rafter rise run this formula is from the pythagorean theorem. Roofing cost can vary widely depending on the size and complexity of your roof type of materials you use as well as your location. So if you divide your answer of a product of length times height by two you will get the area of a triangle.

The length l times the height h of a triangle is twice its area a2. To accurately calculate the area of your roof you must first determine its slope or pitch. You can also calculate roof pitch even without using a roof slope calculator. To get the slope of your roof based on degrees roof rise or x inches per 12 run use our roof pitch calculator.

Otherwise use the table or diagram below. Here are the equations you may use to solve for the length of the slope and the rafter. Medium steep slope roof pitch of 9. Medium slope roof pitch of 6.

Ranch house using asphalt roof shingles. Medium low slope roof pitch of 3 or 4. Use the following formula which also describes a right triangle. The average roof replacement cost is 4 200 6 600 on a 1 600 sq ft.