How To Layout A Roof Rafter

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.

How to layout a roof rafter.

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. Marking the birdsmouth and the ridge board setback. Let s consider a basic gable wood roof framing design. Floor beam span tables of residential structural design we will now look at roof rafter and beam design.

The easy way to lay out and build your rafters. The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial. For every foot of run. Use a tape measure to measure the entire width of your building.

To lay out a common rafter you need the pitch of the roof expressed in units of rise per foot of run. Align the back edge of the tongue with the 187 7 8 mark. Layout your sheet of plywood on sawhorses. Facing the long side of your material measure down from the top edge 8.

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. Do not download and re upload this video. Just share the link. Continuing on from part 3.

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. Then draw a line across the width of the plywood from that mark. In the gable roof example shown here a rafter with 6 in 12 pitch rises 6 in. Rafter layout and cutting sequence.

Run is the horizontal distance that the rafter covers. 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. 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. Use a circular saw or jigsaw to make the cut.