In pitched roof construction, what term is used for the lumber section located directly under the roof decking that runs from the ridge to each side wall?

In pitched roof construction, what term is used for the lumber section located directly under the roof decking that runs from the ridge to each side wall?

• A. Beam
• B. Truss
• C. Joist
• D. Purlin

Answer: (A)

The big idea here is recognizing how roof framing members are named by their role in carrying the load. The long lumber piece that sits directly under the roof decking and runs from the ridge toward the side walls acts as the main load‑carrying member in that section of the roof. In many roof assemblies this primary horizontal member is called a beam because it spans between supports and carries the roof loads down to the walls. It’s the main support path for the decking along that slope. A truss is a prebuilt, triangulated frame that carries loads as a unit, not a single sloped member under the decking. A joist is typically a smaller member used to support floors or ceilings and isn’t the primary roof slope member. A purlin is a secondary support that helps hold up rafters or decking but is considered a secondary member rather than the primary beam running from ridge to wall.

The big idea here is recognizing how roof framing members are named by their role in carrying the load. The long lumber piece that sits directly under the roof decking and runs from the ridge toward the side walls acts as the main load‑carrying member in that section of the roof. In many roof assemblies this primary horizontal member is called a beam because it spans between supports and carries the roof loads down to the walls. It’s the main support path for the decking along that slope.

A truss is a prebuilt, triangulated frame that carries loads as a unit, not a single sloped member under the decking. A joist is typically a smaller member used to support floors or ceilings and isn’t the primary roof slope member. A purlin is a secondary support that helps hold up rafters or decking but is considered a secondary member rather than the primary beam running from ridge to wall.