How To Lay Out Roof Rafters

There are a number of methods to accomplish marking and cutting out rafters.

How to lay out roof rafters.

Today we are tackling a big beginner lesson which is common rafter layout and cutting. Before you cut your boards you ll need to measure the width of your building and calculate the exact length of each rafter. Rafters should always be cut and installed with the crown up. The first step in building the roof rafters is to cut one rafter board to length with the ends angled properly and then to mark and cut the birds mouth and seat on the rafter.

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. The pitch and span of your roof will dictate how long of a rafter you ll need use maximum span calculator to help you find your rafter size. The ridge end of the rafter and often the eve end will need to be cut to the angle of the roof slope. The roof on this shed is a 4 in 12 slope which makes it a 18 and.

Place a 2 by 6 board on sawhorses to lay out the first full length or common rafter. The roof rafters provide integral structural support to the roof. Roof layout requires a number of steps. This article will discuss a gable roof without valleys or dormers because it s the most common and the easiest for a first time builder to tackle.

I will attempt to describe the method i find that works the best for me. Check the board for crown any slight curve in the length and designate the outside of the crown as the top side of the rafter. For every foot. If you look at the rafter span chart you ll notice that 2x4s can be used for rafters on spans up to 11.

To lay out a common rafter you need the pitch of the roof expressed in units of rise per foot of run in the gable roof example shown here a rafter with 6 in 12 pitch rises 6 in. After you determine the rise span run line length and pitch the next step is to lay out the rafters or mark the cuts on a pattern rafter to create the roof.