A structural framing member that extends from the ridge or hip of a roof down to the wall plate, supporting the roof deck and loads.

A rafter is a structural framing member that extends from the ridge board or hip of a roof down to the wall plate at the eaves, serving as the primary load-bearing element that supports the roof deck, roofing materials, and transfers loads including dead loads, live loads, snow loads, and wind loads to the building’s wall and foundation systems. These sloped structural members form the skeleton of pitched roof systems, creating the roof’s shape and providing the framework for attaching roof sheathing, insulation, and finish roofing materials while maintaining the structural integrity necessary to resist various environmental forces and building loads. Rafters are fundamental components in traditional stick-frame construction and remain essential elements in residential and light commercial building construction where pitched roofs are desired for aesthetic, functional, or climatic reasons.

Rafters are utilized in various roof construction applications including gable roof systems where common rafters extend from the ridge board to the wall plates on opposite sides of the building, creating the triangular profile characteristic of gable roofs, hip roof construction where hip rafters form the intersection lines between roof planes and common rafters fill in the remaining areas, shed roof applications where rafters extend from a high wall to a lower wall creating a single-slope roof design, gambrel and mansard roof systems where rafters are arranged in multiple slopes to create complex roof profiles, dormer construction where rafters frame the vertical and sloped surfaces of roof projections, and specialty applications such as cathedral ceilings, exposed beam construction, and architectural features where rafters may serve both structural and aesthetic functions. Each application requires specific rafter sizing, spacing, and connection details appropriate to the loads and spans involved.

The design and sizing of rafters involves structural calculations that consider span length, spacing between rafters, anticipated loads including dead loads from roofing materials and live loads from snow, wind, and maintenance activities, lumber species and grade that determine allowable stresses and deflection limits, roof slope and geometry that affect load distribution and connection requirements, and building code requirements that establish minimum standards for structural adequacy and safety. Rafter sizing typically follows span tables provided in building codes or requires engineered design for complex or heavily loaded conditions, with common residential rafters ranging from 2×6 to 2×12 inches depending on span and load requirements, spaced typically 16 or 24 inches on center to provide adequate support for roof sheathing and distribute loads effectively.

Fun Fact: The word “rafter” comes from the Old English “raefter,” meaning beam or spar, and traditional rafter construction techniques have remained largely unchanged for centuries, with many historic buildings still using the same basic rafter framing principles developed by medieval carpenters.

• Hip Rafter
• Jack Rafter
• Rafter Tie