Building with Hip Jack Rafters for Strength and Durability

Hip jack rafters are a crucial part of a hip roof's structure, providing additional support and stability to the roof.

They are typically installed at a 45-degree angle, which helps to distribute the weight of the roof evenly.

This helps to prevent the roof from sagging or collapsing under heavy loads.

A hip jack rafter can span up to 20 feet without the need for intermediate support.

This makes them an ideal choice for larger roofs where additional support is needed.

By using hip jack rafters, you can create a stronger and more durable roof that can withstand harsh weather conditions and heavy loads.

Regular inspection and maintenance are essential to ensure the longevity of hip jack rafters.

This includes checking for signs of damage or wear and tear, and making repairs as needed.

Proper installation and construction techniques are also crucial to ensuring the strength and durability of hip jack rafters.

For a hip jack rafter, it's essential to keep the top plane of the common rafters in line with the top plane of the hip rafter. This ensures the sheathing lies flat.

To achieve this, you'll need to make a birdsmouth cut into the hip rafter, which is a cut made into the underside of the rafter to fit snugly over the top of the wall plate. The birdsmouth cut should be approximately 4" into the 9.25" high double 3×10 hip rafter.

The heal cut, which is the cut made at the end of the rafter, should be about 4" into the 9.25" high hip rafter. This is to accommodate the birdsmouth cut and ensure a secure fit.

To lay out a hip rafter, start by marking two plumb-cut lines 1-1/2 inches apart at one end of the hip rafter. Cut both lines with a 45-degree bevel to form a point or cheek cut.

Here's a quick reference guide to the key measurements for a hip rafter:

To keep the top plane of common and hip rafters in line, you'll need to consider the birdsmouth cut on the hip rafter. If you're using hurricane ties for the 2×6 common rafters, the top plane of the rafters will be 5.5″ above the outer corner of the double 2×8 girders between the 6×6 posts.

For hip rafters, it's essential to use a larger size, usually one size larger than common rafters, to support the load. In this case, the hip rafter will be a double 3×10, with a 4″ birdsmouth cut into it to fit over the corner of the house.

The heel cut on the hip rafter will need to be approximately 4″ into the 9.25″ high rafter. This is because the hip rafter will be covering off the corner of the house at 135 degrees from the front face and side face of the house.

To lay out a hip rafter, start by marking two plumb-cut lines 1-1/2 inches apart at one end of the hip. Cut both lines with a 45-degree bevel to form a point or cheek cut.

Here's a summary of the key measurements to keep in mind:

The 9/12 side of your roof is a bit different from the 6/12 side, and it's worth understanding why. The birds mouth has been replaced with a Rafter Support Block.

This is because the app assumes both walls have the same height, and for the wall to have the same height and same overhang with the selected roof pitch, your rafter will need a support block underneath. You can think of this support block as a truss heel of some sort.

You can raise your wall on the 9/12 side to keep a birds mouth, but you need to calculate the height difference first. To do this, compare the height above plate from the 6/12 side to the height above plate from the 9/12 side.

For example, on the 9/12 side, the height above plate is 7 & 1/8", and on the 6/12 side, it's 3 & 3/4". The difference is 7 & 1/8" minus 3 & 3/4", which is 3 & 3/8". That's how much you'd need to raise your 9/12 side wall.

The hip jack rafter is a type of roof framing that's both efficient and strong.

It's designed to be a hybrid between a jack rafter and a hip rafter, combining the best qualities of both. The hip jack rafter is typically used in gable-end roof construction, where it provides additional support to the roof's hip end.

Its unique design allows it to handle the stresses of a hip roof, while also being lighter and more cost-effective than traditional hip rafters.

The hip jack rafter is a type of roof framing member that is typically used in conjunction with a hip rafter.

It's usually installed at an angle of 45 degrees to provide additional support to the roof.

The hip jack rafter is usually 2x4 lumber, which is a standard size for many framing applications.

The length of the hip jack rafter will depend on the specific design of the roof, but it's often around 10 to 12 feet long.

In some cases, the hip jack rafter may be longer or shorter than this, depending on the specific requirements of the project.

The hip jack rafter is usually attached to the hip rafter using a 2x4 or 2x6 rafter hanger, which provides additional support to the joint.

This type of rafter is often used in conjunction with a hip rafter to create a strong and stable roof structure.