Framing & StructuralQuestion 362 of 700
CALCULATION: A deck uses 2x8 pressure-treated joists of a species with a span table value of 12 feet at 16 inches on center. If the framer moves the joists to 12 inches on center, the allowable span will generally:
a.Increase somewhat, because closer joists each carry less load
b.Decrease to zero
c.Stay exactly the same
d.Double to 24 feet
Explanation
Spacing joists closer together (16 to 12 inches on center) gives each joist a smaller tributary load, so span tables allow a somewhat longer span at the tighter spacing. It does not drop to zero, stay identical, or double; the increase is modest, per the table, not a doubling.
Law Reference: 2025 CA Residential Code §R507.6Practice all 700 questions free — no signup required.
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