A carpenter is framing a roof and must decide between installing a ridge board and a ridge beam. Which statement correctly distinguishes the two elements?
- AA ridge board is a structural member that carries rafter loads and eliminates the need for rafter ties
- BRidge boards and ridge beams are interchangeable terms for the same framing member with no functional difference
- CA ridge beam is only used in flat roofs and never requires additional support posts
- DA ridge board is non-structural and requires the rafters to be tied together (typically by ceiling joists) to resist outward thrust, while a ridge beam is a structural member designed to carry rafter reactions
Show answer & explanationAnswer & explanation
Correct answer: D. A ridge board is non-structural and requires the rafters to be tied together (typically by ceiling joists) to resist outward thrust, while a ridge beam is a structural member designed to carry rafter reactions
A ridge board simply provides a nailing surface where opposing rafters meet; it carries no load and relies on ceiling joists or rafter ties to resist the outward thrust of the rafters. A ridge beam, by contrast, is designed as a structural beam that actually supports the rafter end reactions, often eliminating the need for rafter ties.
Why the other options are wrong
- A. This reverses the definitions; a ridge board is not structural.
- B. They are not interchangeable; their structural function differs significantly.
- C. Ridge beams are used in various roof shapes and often need post or wall support, not just flat roofs.
Ridge Board vs Ridge Beam
A ridge board is a non-load-bearing member requiring rafter ties, while a ridge beam is a structural member that supports rafter reactions directly.
- Ridge board = nailing point only, needs ties
- Ridge beam = structural, carries rafter loads
- Ridge beams often need post/wall support
Memory trick: Board = 'boring' (no load); Beam = 'bears' the load.