Type: Structural Beam

Description: Rafters are inclined structural members that extend from the ridge or hip of the roof to the eaves, providing support to the roof deck and its loads. They are typically made of wood, steel, or reinforced concrete and are arranged in a series to form the primary framework of a pitched roof. Rafters are essential in transferring the weight of the roof to the building's walls or supporting structures, ensuring the stability and integrity of the roof system.


  1. Material: Wood, Steel, Reinforced Concrete
  2. Shape: Rectangular or I-shaped cross-section
  3. Orientation: Inclined, typically at an angle corresponding to the roof's pitch
  4. Length: Varies depending on the span of the roof and design specifications
  5. Spacing: Typically spaced at regular intervals, often between 16 to 24 inches on center


  1. Ridge Beam: Rafters connect to the ridge beam at the roof's apex, providing a peak for the roof structure.
  2. Wall Plate: The lower ends of the rafters rest on the wall plate, transferring the roof load to the walls of the building.
  3. Purlins: Horizontal members that support rafters midway along their length to reduce the span and increase rigidity.
  4. Ceiling Joists: Work in conjunction with rafters to provide a horizontal framework, tying the bottoms of opposing rafters together and resisting outward thrust.
  5. Roof Decking: Rafters support the roof decking, which is the layer of material, usually plywood or oriented strand board (OSB), that forms the base of the roof covering.

Example Usage:

  • "The carpenters installed the rafters at a 45-degree angle to ensure the roof would be steep enough to shed snow effectively."
  • "Structural analysis of the building revealed that the wooden rafters needed reinforcement to comply with the updated building codes."

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