Deck Joist Span

Deck Joist Overhang (Cantilever)

Overhang length is never just “whatever is left on the board.” DCA 6 caps it two ways.

The LO vs L/4 rule

Table 2 lists an allowable overhang LO for each species, size, and spacing. Separately, the overhang may not exceed one-fourth of the actual joist span L. Your maximum is the lesser of those two numbers.

Example: Southern Pine 2x10 at 16″ o.c. lists LO = 3'-5". If the joists only span 10'-0" clear, L/4 = 2'-6", so the overhang stops at 2'-6" even though the table shows more.

Why wider spacing can show a longer overhang

AWC explains that overhang deflection under the 220 lb point load improves when the back span shortens. Wider spacing often reduces allowable main span, which can raise the tabulated overhang. Always re-check L/4 for your real layout.

Full overhang column

See every LO value beside its span on the deck joist span chart, or compute both outputs with the calculator.

Deck joist span chart / table (AWC DCA 6)

Full Table 2 values: three species groups × four sizes × three spacings, with span and overhang.

Source: AWC DCA 6-15 PDF, Table 2.

Disclaimer

This site is a reference tool. Span and overhang values are transcribed from the American Wood Council DCA 6-15 Table 2 (based on the 2015 IRC). It is not engineering design. Always follow your local building code and a licensed design professional. These tables do not apply to snow loads above 40 psf, hot tubs, roofed decks, or other concentrated loads.