When framing a 5 ft by 5 ft opening in a wood joist floor intended for a stairwell, which framing method is required?

When framing a 5 ft by 5 ft opening in a wood joist floor intended for a stairwell, which framing method is required?

• A. Reinforced with a bolted steel angle and plate
• B. Double header and trimmer joist
• C. Double header joists
• D. Use joist hangers

Answer: (B)

When you cut a five-by-five opening in a wood floor that will be used for a stairwell, the loads from the joists above must still have a solid path to the rest of the structure. The right way to do this is to install a double header spanning the opening, with trimmer (jack) joists bearing on that header to carry the ends of the joists that cross the opening. The double header provides the main support across the gap, while the trimmer joists transfer the load from the ends of the crossing joists down into the header and out to the sides of the opening. This keeps the floor above from sagging or failing at the opening. Using only a single header wouldn’t provide enough strength to carry the joist loads, and joist hangers by themselves don’t create the necessary load path across the opening. A bolted steel angle and plate is not typically required for a standard residential wood floor opening of this size. The double header with trimmer joists is the proper framing method for this stairwell opening.

When you cut a five-by-five opening in a wood floor that will be used for a stairwell, the loads from the joists above must still have a solid path to the rest of the structure. The right way to do this is to install a double header spanning the opening, with trimmer (jack) joists bearing on that header to carry the ends of the joists that cross the opening. The double header provides the main support across the gap, while the trimmer joists transfer the load from the ends of the crossing joists down into the header and out to the sides of the opening. This keeps the floor above from sagging or failing at the opening.

Using only a single header wouldn’t provide enough strength to carry the joist loads, and joist hangers by themselves don’t create the necessary load path across the opening. A bolted steel angle and plate is not typically required for a standard residential wood floor opening of this size. The double header with trimmer joists is the proper framing method for this stairwell opening.