How To Find The Pitch Of A Roof With A Framing Square

How to use a framing square and its etched on tables to figure out roof slope rafter lengths.

How to find the pitch of a roof with a framing square.

Locate the level s 12 inch mark. 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. The most precise way to find the roof s slope is by measuring it from the underside.

It is often compared to slope but is not exactly the same. On a ladder beside the roof place the level a foot or so up the roof hold it level and measure from the 12 inch mark on the level s bottom straight down to the roof. 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. A carpenter s framing square includes some tables stamped right into the tool itself.

Pitch measurement method 1. Use a level against the underside of the rafter you re measuring to get the most accurate value. Finding the pitch of a roof is simple with a speed square. Pitch of hips the pitch is based on a 12 run on the framing square.

Fix stair gauges on the framing square to mark the pitch. Directly below the 6 inch mark on the framing square read the required rafter length 13 42 per foot of run for a 6 inch rise 6 in 12 roof. The swanson speed square is a popular tool with most carpenters. 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.

Access one of the rafters then take the measurement this way. 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. If this distance measures 4 inches you have a 4 in 12 pitch. 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.