how to cut a birds mouth notch

When you’re building a shed or some other building and assembling the roof for it, you’ll need to learn some new terms and some new types of cuts. A birdsmouth cut is commonly used for a broad range of roofs, including basic gable roofs from homes, shed roofs, and other roof layouts involving rafters.

The term “birdsmouth cut” may seem odd and mysterious at first, but it’s actually a fairly simple joint to make. You’ll need to measure carefully and cut precisely, but once you’ve done a couple of these cuts, it won’t seem difficult at all.

In this guide, we’ll explore what a birdsmouth cut is, why it’s important, and how to make one. We’ll also offer some tips on securing the rafters in place once you’ve completed the birdsmouth cut.

Why is the Birdsmouth Essential?The design of the birdsmouth ensures that the weight of the roof is evenly distributed over the walls. This even distribution prevents undue stress on any single point of the roof structure, ensuring longevity.

  • Toenails: These are hammered straight into the wall plate through the birdsmouth.
  • Metal Rafter Tie Down Plates: These plates provide an extra degree of security for individuals seeking it.

What is a Birdsmouth Cut?

A birdsmouth joint is a triangle-shaped notch, or groove cut into a rafter, allowing it to sit at the correct angle on top of a supporting timber, stud, or wall. This joint is also called a bird’s beak joint or a bird’s beak cut.

Think about it this way. You’ve got a stud standing upright. There is a flat area on top of the stud, perhaps one or two inches across. The two pieces of wood will only come into contact with one another along the top edge if you place another board, like a rafter, at an angle against the top of the stud. You only have one point of contact, which isn’t very reliable.

However, if you cut the appropriate notch into the board—the desired rafter—the two pieces of wood will actually fit together. More surface area is in contact with you, and the rafter can be fastened at the right angle more readily and firmly.

Benefits of a Birdsmouth Rafter Cut

A much more stable method of assembling a roof is to use a birdsmouth cut for each rafter, whether you’re working with studs or a whole wall plate. Because of those triangular birdsmouth notches, you can hook each rafter onto the wall plate rather than balancing them at angles on the wall plate’s very edge.

Additionally, this style of roof assembly enables more equitable weight distribution across the wall and roof. Because the joint creates a strong bond, weight, force, or stress can be distributed evenly, ensuring a more durable structure.

There are several ways to create birdsmouth rafter cuts, but for the purposes of this tutorial, we’ll keep things straightforward. You’ll need a selection of basic tools.

First of all, you need a couple of saws. For cutting birdsmouth rafter, a circular saw and a hand saw are the most useful tools. You might already have one or both of these saws on hand if you’re building a shed on your property or remodeling your own house; if not, you might want to think about getting them.

Apart from a handsaw and a circular saw, you will also require a tape measure. Typically, these measuring devices consist of a rigid tape that you can extend and retract as necessary. Most homes have one on hand. If you don’t have one or can’t locate yours, you can buy one from any retailer of household goods.

The final two tools you’ll require are a carpenter’s pencil and a carpenter’s square. These tools will aid in precision and in identifying the locations where the wood needs to be cut in order to form a birdsmouth joint.


What can you use instead of a bird mouth cut?

Galvanized metal connectors, sometimes called hurricane clips or by a common manufacturer’s name, “Simpson Strong-Tie”, can be used in lieu of or in conjunction with birdmouth on a rafter.

What are the rules for birdsmouth cut?

the depth should be one third the width of the rafter , most cut the depth to 1.5″ or two inches on a two by four , the length from the top of the cut to the edge of the rafter is the width of the rafter or 3.5″ .. Not for a 2×6 wall. It also depends on the width of the rafter and the desired width of the tail.

What is the best tool for cutting birdsmouth?

Strategy 1: Use a circular saw. Problem: you can’t cut all the way through so you have to follow up with a jigsaw which doesn’t cut straight. Strategy 2: Use a circular saw mitred at the angle of the cut.