Deck Beam & Joist Span Calculator
Look up maximum deck joist and beam spans straight from the IRC 2021 tables (R507.6 / R507.5(1)) — by species, joist size, spacing, and beam configuration.
Joists
Ledger face to beam face — not total deck length
Max joist span (2x8 @ 16″ OC)11′ 10″
Your span10′ 0″ — OK
Beam
Distance between posts supporting the beam
Beam table column (joist span ≤ 10′)10 ft
No standard Southern Pine beam in Table R507.5(1) reaches 12ft at this joist span. Add a post, upgrade to a different species, or use engineered lumber.
IRC 2021 Tables R507.6 / R507.5(1), 40 psf live + 10 psf dead, No. 2 grade, wet-service. Joist span is measured ledger face to beam face. Beams: 2 rows of 10d nails at 16″ OC along each edge for multi-ply. Verify your local amendments — some jurisdictions differ.