How To Figure Roof Pitch With A Framing Square

How roof pitch is calculated.

How to figure roof pitch with a framing square.

A carpenter s framing square includes some tables stamped right into the tool itself. Finding the pitch of a roof is simple with a speed square. How to use a framing square and its etched on tables to figure out roof slope rafter lengths. Square guides are available at most hardware and home improvement centers.

Roof pitch is the measurement of a roof s vertical rise divided by its horizontal run. The triangle shaped square was invented in 1925 by albert swanson to provide a quick accurate method for marking rafters. To accurately calculate the area of your roof you must first determine its slope or pitch. A 6 inch rise per foot.

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. So if the pitch of your roof is 7 12 place one stair gauge on the vertical part of the framing square the tongue at the 7 inches 18 cm mark and place one stair gauge on the horizontal part of the framing square the body at the 12 inches 30 cm mark. Framing square guides are small inexpensive metal attachments to the framing square that are locked in position on the square s edges at the pitch and run dimensions to define the roof angle and make the repeated marking of the rafters much more efficient. How to find roof slope rafter length on a framing square how would we use our framing square to measure or to calculate the slope and rafter lengths of this historic herefordshire u k.

Find the unit rise say inches per foot of the roof on the top line in the framing square rafter table e g. This article explains how to make quick use of a framing square and its imprinted data to get some basic roof measurement data like roof pitch or slope rafter lengths and end cuts. It is often compared to slope but is not exactly the same. Because of its compact size it is frequently used as a saw guide when cutting framing members as well as a layout tool for quick 45 and 90 degree cuts.