Which truss is constructed with the top and bottom chords parallel and is used as floor joists in multistory buildings and as ceiling joists in flat-roofed buildings?

• A. Parallel Chord Truss
• B. Howe Truss
• C. King Post Truss
• D. Pratt Truss

Answer: (A)

The key idea is the Parallel Chord Truss, which has top and bottom chords that run parallel. That straight, uniform chord arrangement creates a simple, direct load path from the floor or ceiling to the supports, which is exactly what you want for long-span floor joists in multistory buildings and for ceiling joists in flat-roofed buildings.

Because the chords stay parallel, the truss can span between bearing walls while carrying the floor or ceiling loads without needing excessive depth. The web members tie the chords together to resist shear and bending, giving a strong, stable system suitable for repetitive joist spacing and integration with floors and ceilings above and below.

Other truss types differ in how their diagonals and verticals are arranged, which changes their preferred applications. For example, the trusses with diagonals that slope toward the center and a different vertical/diagonal pattern are often chosen for specific bridge or roof configurations and load paths, not as standard floor or ceiling joists for multistory construction. A simple King Post truss is suited for shorter spans and doesn’t provide the long, parallel-chord geometry that makes the parallel chord arrangement practical for floor and ceiling framing.