Roof Rafter Layout

For every foot of run.

Roof rafter layout.

Roof rise this should be calculated from the base of the roof to the highest point of the roof gable the peak. Another option are 2 x 8 rafters spaced 24 inches o c. Once you know the pitch and the total run you can lay out the cuts of the rafter in a number of ways. Let s use this example and find a size of rafter that will work.

Measure up a distance equal to 25 of the width of the rafter as shown in illustration c and put a mark. In the gable roof example shown here a rafter with 6 in 12 pitch rises 6 in. For instance 2 grade 2x4s at 16 on center will span just over 9. To lay out a common rafter you need the pitch of the roof expressed in units of rise per foot of run.

Rafter run outer wall this should be measured starting from the center of the roof span and then extending to the very edge of the exterior wall. Here the number is 1166 66 inches. Looking through the center of the table we can find a couple of options. Flip the square over and place the tongue along the line made in illustration b.

Run is the horizontal distance that the rafter covers. For a gable roof the run is measured from the centerline of the ridge board to the outside edge of the top of the wall. There is no standard spacing it depends on what size of rafters you want to use and the span of your shed. Draw a line down the edge of the tongue as shown in illustration b of the roof layout.

Here the number is 941 86 inches.