Which statement about Heavy Timber Arch joists is accurate?

Which statement about Heavy Timber Arch joists is accurate?

• A. Uses lightweight framing
• B. Joists consisting of 2x6s and 1x6 Sheathing
• C. Does not require any burn rule
• D. Uses steel only

Answer: (B)

Heavy Timber construction relies on solid wood members with enough mass to resist fire and carry loads. In an arch joist system, a common built-up configuration uses multiple 2x6 lumber pieces with a 1x6 sheathing layer to form the curved joist. This arrangement keeps the timber as the primary structural material, providing the strength and fire performance expected of heavy timber, rather than relying on lightweight framing or steel alone. The idea that no burn rule applies ignores the fire-performance aspects of timber—heavy timber relies on predictable charring and mass to maintain structural integrity during exposure. A steel-only system contradicts the timber-based approach, which is central to heavy timber construction.

Heavy Timber construction relies on solid wood members with enough mass to resist fire and carry loads. In an arch joist system, a common built-up configuration uses multiple 2x6 lumber pieces with a 1x6 sheathing layer to form the curved joist. This arrangement keeps the timber as the primary structural material, providing the strength and fire performance expected of heavy timber, rather than relying on lightweight framing or steel alone. The idea that no burn rule applies ignores the fire-performance aspects of timber—heavy timber relies on predictable charring and mass to maintain structural integrity during exposure. A steel-only system contradicts the timber-based approach, which is central to heavy timber construction.