Understanding Valley Jack Rafter Roof Framing

A Valley Jack Rafter roof framing is a type of framing used in roof construction, particularly in areas with heavy snowfall or high winds.

This type of framing is designed to provide additional support and stability to the roof, helping to prevent damage and collapse.

The Valley Jack Rafter is typically used in conjunction with other framing elements, such as valleys and hips, to create a sturdy and secure roof structure.

In areas with heavy snowfall, the Valley Jack Rafter can help to distribute the weight of the snow more evenly across the roof, reducing the risk of collapse.

Valley jack rafters are a crucial part of a roof's structural support, particularly in concave roof slope changes. They provide essential support to the valley beam.

The code may be misleading about valley beam behavior, but our experience shows that valley beams will always behave as structural members regardless of slope. This is due to the inherent downward loading from the jack rafters.

The downward loading from jack rafters means that valley beams need to be designed and constructed as structural members. This is a critical aspect of residential roof framing.

In fact, valley beams should be treated as structural members regardless of slope, a practice that's often overlooked in residential construction.

Hip rafters play a crucial role in the construction of a valley jack rafter system. They are typically located at the peak of the roof and are used to support the ridge beam.

Hip rafters are usually shorter than the other rafters in the system, and their length depends on the type of roof being built. The valley jack rafter system typically uses a combination of hip rafters and jack rafters to create a sturdy and stable roof structure.

Hip rafters are laid out and cut in the same manner as valley rafters. They both have a single or double beveled plumb cut where they meet the ridge board. This cut helps the rafter sit flush against the ridge board, creating a strong and stable connection. A bird’s mouth is also used on hip rafters, where they sit on the inside or outside wall corners. This type of cut allows the rafter to fit snugly into place, creating a secure joint.

The valley rafter has a different pitch than the common rafters, with a 12-in-17 pitch compared to the common rafters' 12-in-12 pitch.

This difference in pitch means the valley rafter takes 17 inches of run to rise the same distance the common rafters rise in 12 inches.

To mark the plumb cut on the valley rafter, you'll need to use a double bevel, whereas the common rafters are marked with a framing square for a 45° angle and cut square.

It's essential to check each piece of lumber and mark the crown before cutting to ensure all the crowns are pointing up, preventing waves from marring the finished roof.