How Do You Cut a Hip Rafter to Frame a Hipped Roof

Cutting a hip rafter is a crucial step in framing a hipped roof, and it requires some precision to get it right. The hip rafter is the rafter that meets the ridge beam at a 45-degree angle, forming the hip of the roof.

To cut a hip rafter, you'll need to use a miter saw or a circular saw, as these tools allow for precise angled cuts. The angle of the cut is critical, as it determines the pitch of the roof.

A hip rafter typically has a 45-degree angle, but the exact angle may vary depending on the design of the roof. In a standard hipped roof, the hip rafters are typically 16 inches on center, which means they are spaced 16 inches apart.

Measuring from the rafter's edge is a game-changer when it comes to laying out hip rafters. This approach eliminates the need to deal with fractions and makes calculations much simpler. By taking measurements along the bottom edge of the rafter, you can ensure accurate cuts and reduce the risk of mistakes.

To measure from the rafter's edge, use a metric tape, as it's easier to work with when math is involved. This is because the metric system eliminates fractions, making calculations more straightforward. The math itself is simple, relying on right triangles and dimensions based on the Pythagorean theorem.

One of the benefits of measuring from the rafter's edge is that you can use the same dimensional lumber for all the rafters and align the bottom edges. This eliminates the need to make adjustments for dropping the hip. For example, on a roof with 2×6 lumber, you can leave the tops of the jacks ¼ in. above the hip, allowing for airflow and a clean fit.

To get started, it's essential to visualize how the parts fit together and understand the layout of the roof. This involves looking at the roof in plan view, where you can see the hip-rafter run as the hypotenuse of a simple 90° triangle with equal sides. Use a Speed Square to lay out both sides of the hip rafter on the plate, establishing point A where the layout line meets the inside edge of the top plate.

Here's a step-by-step guide to measuring from the rafter's edge:

By following these steps and measuring from the rafter's edge, you'll be able to accurately layout your hip rafters and achieve a professional finish.

To lay out a hip rafter, you'll need to mark two plumb-cut lines 1-1/2 inches apart at one end of the hip. This will give you a point or cheek cut, which is essential for a hip rafter.

The seat cut location is dictated by the heel height, not the wall plate width like on a common rafter. You should have written down the heel height earlier, which in our case is 7-⅜ inches.

For a hip rafter, you'll need to take into account hip-drop, which is calculated using the formula: 6.5 + RUN + 6 + PITCH + HIP/VAL.

To cut a hip rafter plumb cut, you'll need to set your circular saw to 45° and mark a plumb line on the end of the timber. Make sure the bow/camber is upward to avoid any issues.

You'll also need to mark back square from the plumb line half the thickness of the ridge, which in our case is 25mm. This will give you the correct point for the hip rafter.

Here's a quick reference table to help you remember the key measurements for a hip rafter:

The key to layout is to know exactly where to begin and end measurements, and it's essential to measure from the bottom edge of the rafter for exact layout.

Measuring from the center of the board can be tricky, but taking all measurements from the edge of the board simplifies the process. This approach eliminates the need to make adjustments for measuring from the center.

In plan view, the hip-rafter run is the hypotenuse of a simple 90° triangle with equal sides, making it easier to visualize and calculate the measurements.

Here's a step-by-step guide to laying out hip rafters:

By breaking down the process into manageable steps, you'll find it easier to understand and execute the layout and cut of hip rafters.

Looking at the roof in plan view can be a game-changer for understanding hip rafter layout. By visualizing the roof as a 2D drawing, you can see that the hip-rafter run forms the hypotenuse of a 90° triangle with equal sides.

A Speed Square is a handy tool for laying out the hip rafter on the plate. Establish point A where the layout line meets the inside edge of the top plate, and then measure from point A to the layout of the nearest king-common rafter.

Measuring from point A to the nearest king-common rafter will give you the run and length of the hip rafter. This measurement is crucial for calculating the length of the hip rafter, which represents a line along the bottom edge of the board from the short point of the double-bevel cut to the short point of the seat cut.

The hip rafter's length is a critical measurement that will help you cut the rafter to the correct size. By understanding how to measure and layout the hip rafter, you can ensure a clean and strong fit in the roof's corners.

Rafter layout is a crucial step in building a roof, and it's essential to get it right to avoid costly mistakes and ensure a sturdy structure. Measuring from the rafter's bottom edge is key to accurate layout, as it eliminates the need to deal with fractions and makes calculations simpler.

A simple 90° triangle with equal sides can help you visualize the hip-rafter run in plan view, making it easier to calculate the length of the hip rafter. This is because the hip-rafter run is the hypotenuse of the triangle.

To lay out a hip rafter, start by marking two plumb-cut lines 1-1/2 inches apart at one end of the hip, then cut both lines with a 45-degree bevel to form a point or cheek cut. This will give you a clear starting point for your measurements.

The seat cut location is dictated by the heel height, which must be the same for all hips to ensure a level roof. For example, if the heel height is 7-⅜ inches, measure down from the top of the rafter to find the seat cut.

To calculate the hip rafter length, use the equation a2+b2=c2, where a is the run, b is the rise, and c is the rafter length. Alternatively, you can think of it as the run times itself plus the rise times itself is the rafter length squared.

Here's a quick reference for measuring and setting out hip rafter lengths:

Remember to always measure from the edge of the board, as this eliminates the need to make adjustments for measuring from the center of the board.