Roof Support Birds Notch

As a rule of thumb a birds mouth notch on a rafter should be no less than one third of the timber width and no more than half.

Roof support birds notch.

To illustrate a 2x12 rafter that meets the irc s d 4 notching limitation cannot have a notch deeper than 2 13 16 inches 11 1 4 divided by 4. The birdsmouth joint also called the birds beak cut or birds beak joint is a small triangular shaped cut out at the base of a roofing joist that allows the joist to sit nicely on top of the wall plate top of the wall before the roof starts. When you cut the rafters you ll need to make 3 separate cuts. Notch at the top of the rafter joist allowed to be 1 3 the rafter depth if no further away from the end of the rafter than the rafter depth.

Simple jig to cut your birds mouth notches. 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. 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. The roof rafters provide integral structural support to the roof.

The slim now available to buy at https carlrogers copatreon. The ridge cut also called the plumb cut at the top of the rafter the birdsmouth cut. This isn t a problem on a roof with a shallow 4 12 pitch since the seat cut could be as long as 8 7 8 inches. You can also take steps to prevent them from returning if you ve had problems in the past.

How much can you cut out of a birdsmouth. Seeing as how you re not allowed to remove birds from your roof once they ve made themselves at home your only option is to prevent them from entering in the first place.