Roof Rafter Layout

Let s use this example and find a size of rafter that will work.

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. Here the number is 941 86 inches. Flip the square over and place the tongue along the line made in illustration b. For instance 2 grade 2x4s at 16 on center will span just over 9.

There is no standard spacing it depends on what size of rafters you want to use and the span of your shed. 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. Measure up a distance equal to 25 of the width of the rafter as shown in illustration c and put a mark. Looking through the center of the table we can find a couple of options.

Here the number is 1166 66 inches. For standard shed roof rafter spacing see rafter span chart. In the gable roof example shown here a rafter with 6 in 12 pitch rises 6 in. To lay out a common rafter you need the pitch of the roof expressed in units of rise per foot of run.

Once you know the pitch and the total run you can lay out the cuts of the rafter in a number of ways. 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. Marking the birdsmouth and the ridge board setback. Another option are 2 x 8 rafters spaced 24 inches o c.

Draw a line down the edge of the tongue as shown in illustration b of the roof layout.