The schedule gives allowable clear spans for this loading of 5 feet 2 inches for a two-ply 2x10, 6 feet 5 inches for a three-ply 2x10 and 7 feet 4 inches for a four-ply 2x10. The clear opening between jack studs measures 6 feet 8 inches. Which header satisfies the schedule? The schedule treats the plywood spacer option as nonstructural filler and gives it no additional span allowance.
- AA two-ply 2x10 header
- BA three-ply 2x10 header
- CTwo 2x10 plies with a plywood spacer between them
- A four-ply 2x10 header
Where to look it up
Explicit exercise assumptions; not a universal code requirement.
Why D is correct
Convert all spans to inches: the opening is 80 inches; allowable spans are 62, 77 and 88 inches for two, three and four plies. Only the four-ply choice reaches 80 inches. The plywood spacer has no additional allowance under the supplied schedule. This answer is a schedule comparison, not a general capacity claim about all plywood-containing headers.