How To Birdsmouth A Roof Rafter

Pitch rise run x 2.

How to birdsmouth a roof rafter.

Rise is the vertical distance from the top plate of. Possibly the most satisfiying part of the roof yet. Multiply your pitch by 24 to determine the rise per foot of run. Among the most important individual components is the birdsmouth joint.

Due to the width. This notch allows the beam to rest flush onto the top plate. The roof rafters provide integral structural support to the roof. This 90 degree angle forms the bird s mouth.

From that line across the rafter draw a perpendicular line at the 1 1 2 inch mark out towards inside part of the rafter. From the marked point draw a line at the same angle as the pitch of the rafter up and make a mark at 1 1 2 inches. The ridge cut also called the plumb cut at the top of the rafter the birdsmouth cut which itself comprises 2 different cuts where the rafter meets the building s wall and the tail cut at the base of the rafter. A birdsmouth cut involves taking a notch shaped like a bird s mouth out of each rafter where it meets the top plate.

When you cut the rafters you ll need to make 3 separate cuts. How to cut bird s mouths in rafters step 1. So to summarise the full process is as follows. Before you cut your boards you ll need to measure the width of your building and calculate the exact length of each rafter.

Make one rafter that has the bird s mouth cut in place and extends out past that for your roof overhang test fit it in place and mark it pat for pattern rafter to use in cutting its sisters. Also known as a bird s mouth joint or sometimes a bird s beak notch this type of cut is typically used to securely connect a rafter to the top of a supporting wall with the help of a wall plate. Calculate the pitch of your roof. In my photo above the green rafter line length is from the plumb cut face or ridge board face to the plumb cut face of the bird s mouth notch.

Measure along the top of the rafter the distance that you calculated in the previous step. The result of this equation represents the. Step 3 cutting out the bird s mouth. Calculate pitch of roof use roof pitch to cut ridge cut use ridge cut as point of reference to form birdsmouth make tail cut.