A framing crew is installing I-joists for a large open-concept living area. The architectural drawings specify a large opening for a stairwell through the floor system. Which of the following is the most appropriate method to frame this opening while maintaining structural integrity?

Question: A framing crew is installing I-joists for a large open-concept living area. The architectural drawings specify a large opening for a stairwell through the floor system. Which of the following is the most appropriate method to frame this opening while maintaining structural integrity?

Answer options:

• Cut the I-joists that run through the opening flush with the opening edge and rely on the subfloor for support. ✅ Install headers (trimmers) between two full-length parallel I-joists (carrying joists) to support the cut ends of the I-joists.
• Use steel angle brackets to attach the cut I-joists directly to the adjacent uncut I-joists.
• Reinforce the cut I-joists with plywood gussets glued and screwed over the webs.

Correct answer: Install headers (trimmers) between two full-length parallel I-joists (carrying joists) to support the cut ends of the I-joists.

Explanation: For openings in an I-joist floor system, a header must be installed between two carrying joists to support the cut ends of the I-joists. This creates a strong box-out. Cutting joists flush without support, using only angle brackets, or simply gusseting cut webs would compromise the structural integrity for a stairwell opening.