How To Cut Roof Rafters With A Speed Square

Before you cut your boards you ll need to measure the width of your building and calculate the exact length of each rafter.

How to cut roof rafters with a speed square.

Photo 2 shows how to use the speed square to mark a 33 1 2 degree angle the same as you would need on a rafter tail for a roof with an 8 12 pitch. A bevel square can also be set to the plumb cut angle and used to mark the rafter s top overhang and bird s mouth cuts. Ability to read a tape measure ruler. 2 lay out a plumb cut on a rafter.

Building plans will specify the slope a roof should have. Demonstrate the basics on calculating laying out and cutting a common rafter for either a full gable roof or for a shed roof on a porch or small addition. And the secret to cutting correct rafter angles is the speed square also known as the rafter square which was invented in 1925 by carpenter albert j. The rafter square makes it easier to cut the correct angles for anyone looking to make custom roof trusses.

Common rafters are the most common type of rafter in construction. The roof rafters provide integral structural support to the roof. If you re framing a gable roof on a new house or building a shed or even a doghouse with a gable roof you ll need to cut a number of roof rafters. Familiarity with using a speed square.

In this first installment we ll start with roof framing. The key to accurately cutting the necessary angles is the proper use of a basic carpentry tool the framing square. The rafter square or speed square does more than mark perpendicular lines. This is the first episode of a series that i am making called construction rocks this series will help teach skills useful when building a house.

Locate the desired roof pitch on the common top cuts table of.