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Structural

Rafter

In Plain English

A sloped framing member that forms the framework of a pitched roof and carries the roof's weight to the walls below.

Definition

A sloped structural member that forms the framework of a pitched roof and supports the roof covering. Rafters extend from the ridge board or ridge beam at the peak down to the wall plate or beam at the eaves. They carry roof loads—including dead load, live load, snow load, and wind load—to the supporting walls or beams.

Why It Matters in Bidding

Rafter framing affects both takeoff quantity and labor productivity — pitch, span, and spacing determine board footage, the cut complexity, and crew hours, especially on stick-framed roofs versus trussed alternatives. An estimator comparing rafter framing to prefabricated trusses must weigh material, field labor, and schedule, since the wrong assumption can swing the framing bid and the crew's exposure to weather and fall-protection cost.

Example

Pricing a custom home with a cathedral ceiling, the estimator chooses stick-framed rafters over trusses and adds field-cutting labor hours because the open ridge beam design rules out prefabricated assemblies.

Related Terms

Frequently Asked Questions

Steeper pitch increases the actual rafter length per horizontal foot, raising board footage, and it lowers crew productivity due to fall-protection needs and harder access. Estimators apply a slope factor to convert plan dimensions to true rafter length, then adjust labor units upward as pitch and height increase.
Stick-framed rafters suit custom rooflines, cathedral or vaulted ceilings, and tight-access jobs where crane-set trusses are impractical. Trusses usually win on speed and labor cost for repetitive spans. The estimator compares material plus field labor against engineered truss packages, factoring schedule and weather exposure into the decision.
Rafters transfer dead load, roof live load, snow, and wind to the walls or beams below. Local code and the structural drawings set member size and spacing for these loads, which in turn drive lumber grade and quantity. Estimators price exactly to the specified size and spacing rather than substituting lighter members.

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