Rafter, Jack

Definition

A jack rafter is a rafter that fills the space between the hip rafter and the top of the wall plate.

Purpose

The purpose of a jack rafter is to support the roof covering and distribute the load between the hip or valley rafter and the wall plate, ensuring a complete and stable roof structure.

Examples of Use

• Jack rafters are used in hip roofs to fill the spaces between the main rafters, providing support and stability.
• In valley roofs, jack rafters extend from the valley rafter to the ridge or the eaves, ensuring a uniform load distribution.
• Jack rafters are essential in complex roof designs to maintain structural integrity and support roofing materials.

Related Terms

• Hip Rafter: The diagonal rafter at the junction of two roof planes.
• Valley Rafter: The rafter extending from an inside angle of the plates toward the ridge or center line of the house.
• Common Rafter: Rafters that run perpendicular to the wall plate and extend to the ridge.

Notes

Proper installation of jack rafters is essential for ensuring the stability and durability of the roof, particularly in complex roof designs.