How To Layout A Roof Rafter

We need to adjust the total run 73 inches in our example by subtracting 1 1 2 inches the full thickness of the ledger adjusted run 71 1 2 inches.

How to layout a roof rafter.

Facing the long side of your material measure down from the top edge 8. In the gable roof example shown here a rafter with 6 in 12 pitch rises 6 in. The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial. Just share the link.

Measure as precisely as possible down to the 1 4 inch 0 64 cm 1 8 inch 0 32 cm or 1 16 inch 0 16 cm. Align the back edge of the tongue with the 187 7 8 mark. The easy way to lay out and build your rafters. Floor beam span tables of residential structural design we will now look at roof rafter and beam design.

Let s consider a basic gable wood roof framing design. Marking the birdsmouth and the ridge board setback. Then draw a line across the width of the plywood from that mark. Place the square as before aligning the 6 mark of the tongue and 12 mark of the body with the top edge of the rafter material.

Before you start cutting you first need to determine how long your roof rafters need to be and the angles at which you ll cut the top and bottom of the rafter. Rafter layout with a framing square this example is for a roof with an 8 12 pitch position the square at the end of the rafter board with the tongue on your left and facing away from you. To lay out a common rafter you need the pitch of the roof expressed in units of rise per foot of run. For every foot of run.

Run is the horizontal distance that the rafter covers. Continuing on from part 3. Layout your sheet of plywood on sawhorses. Draw a line down the edge of the tongue as shown in illustration b of the roof layout.

Rafter layout and cutting sequence. Use a circular saw or jigsaw to make the cut. Position the square with both the 8 inch on the outside edge of the tongue and the 12 inch on the blade on the upper edge of the board. On a shed roof rafter run is the distance from a ledger on the main building to the outside of an addition wall or porch carrying beam.