Define beam.

• A. Laminated build-up lumber or steel used to support vertical loads in absence of a vertical wall under the load.
• B. A decorative horizontal member at the top of a wall.
• C. A vertical post used for support.
• D. A type of roof truss.

Answer: (A)

A beam is a structural member that carries vertical loads across a span, transferring the weight to supports at its ends. It’s used when there isn’t a vertical wall directly under the load, so the beam (often made from laminated built-up lumber or steel) spans between supports to carry the weight above. This distinguishes it from decorative horizontal members, which don’t bear loads; from a vertical post, which is a supporting column; and from a roof truss, which is a framework for the roof.