How far can a 2x10 deck joist span?
A 2×10 deck joist at 16 inches on center can span up to 14 feet (14 ft) in Southern pine under the IRC’s 40 psf live load — 13 feet 7 inches in Douglas fir-larch, hem-fir or SPF, and 13 feet in redwood or western cedar.
How to work it out
- Table R507.6, 40 psf live load, Southern pine, 2×10 at 16 in on center → maximum span 14 ft (4.27 m)
- Margin = maximum − your span = 14 ft − 13 ft = 1 ft → span OK
- 16 ft = 192 in ÷ 16 in = 12 → 12 spaces + 1 = 13 joists
Two-by-tens at 16 in on center frame most decks that reach 12 to 14 ft out from the house. The species gap is narrower than with 2×8s — 14 ft for Southern pine against 13 ft for cedar — but under IRC Table R507.6 a 14 ft clear span at this spacing still only works in Southern pine.
Adjust for your project
More options: Load · Deck
- Joists along the deck
- 13 joists
- If your area’s ground snow load is over 40 psf, pick that load under More options — the spans get shorter.
Southern pine 2×10 at 16 in on center, by design load
| Design load | Maximum allowable span (IRC Table R507.6) | Will your joists work? |
|---|---|---|
| 40 psf live load | 14 ft | Yes — 1 ft to spare on the span |
| 50 psf ground snow | 13 ft 9 in | Yes — 9 in to spare on the span |
| 60 psf ground snow | 12 ft 9 in | No — the span is 3 in too long. Go up a size or close the spacing. |
| 70 psf ground snow | 11 ft 11 in | No — the span is 1 ft 1 in too long. Go up a size or close the spacing. |
What to know about 2x10 deck joists at 16 inches
- Fir and hem-fir run out before 14 ft. A Douglas fir-larch, hem-fir or SPF 2×10 at 16 in stops at 13 ft 7 in. For a full 14 ft clear span in that lumber, tighten the spacing to 12 in (15 ft 8 in) or switch to 2×12s (15 ft 9 in).
- Wider spacing is the usual trade. A 16 ft ledger takes 13 joists at 16 in but 17 at 12 in. If 2×8s at 12 in (13 ft 1 in in Southern pine) cover your span, compare the lumber bill against 2×10s at 16 in before you decide.
- Snow loads bite here too. Southern pine 2×10s at 16 in fall to 12 ft 9 in at a 60 psf ground snow load and 11 ft 11 in at 70 psf — see the table above.
- Room for an overhang. At the 13 ft span above, a Southern pine 2×10 may run up to 3 ft 2 in past the beam (between the table’s 3 ft at 12 ft and 3 ft 4 in at 14 ft). At a 16 ft back span only Southern pine still allows one (3 ft 4 in); the other groups are NP.
- The joists are only part of it. A 13 or 14 ft span puts a lot of load on the ledger bolts, the beam and its footings, and each has its own rules in Section R507.
One measuring habit to break: the span is ledger face to beam face, so a deck that is 14 ft deep overall with the beam set 2 ft back from the edge has a joist span of just under 12 ft, not 14. Measure the real clear distance before you buy longer, heavier joists than the deck needs. For a smaller deck, see How far can a 2x8 deck joist span.
Different size? Use the full Deck Joist Span Calculator.
What you’ll need
- 25 ft tape measureBudget price
A 25 ft tape with a stiff blade and a readable 1/16 in scale covers everything from cut lists to deck layout.
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Snaps long straight lines on sheathing, subfloor and decking — framing lines, cut lines and layout in seconds.
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Frequently asked questions
Can 2x10 deck joists span 16 feet?
Only in Southern pine at 12 in on center, which reaches 16 ft 2 in under a 40 psf live load; the fir group stops at 15 ft 8 in. At 16 in on center you need 2×12s, and only Southern pine (16 ft 6 in) gets there. Otherwise add a beam partway.
How far can a 2x10 deck joist span at 12 inches on center?
In Southern pine, 16 ft 2 in (16 feet 2 inches) under a 40 psf live load — 15 ft 8 in in the fir group and 14 ft 11 in in redwood or cedar.
How far can a 2x10 deck joist span at 24 inches on center?
In Southern pine, 11 ft 5 in (11 feet 5 inches) at a 40 psf live load. Joists at 24 in need 2 in thick wood decking under R507.7; 5/4 boards need 16 in or closer.
How far can a 2x10 deck joist overhang the beam with a 13 ft span?
Up to 3 ft 2 in for Southern pine at a 40 psf live load, interpolated between the 12 and 14 ft back-span columns — so a 3 ft overhang passes. In the fir group the limit is 3 ft 1-1/2 in, in redwood or cedar 2 ft 10-1/2 in.
How far can a 2x10 deck joist span with a 60 psf snow load?
12 ft 9 in (12 feet 9 inches) for Southern pine at 16 in on center — 12 ft 4 in in the fir group and 11 ft 9 in in redwood or cedar.
Other common sizes
- How far can a 2x8 deck joist span — 11 ft 10 in
Sources
- ICC — 2021 International Residential Code, Chapter 5 Floors (Table R507.6 deck joist spans and cantilevers, R507.7 decking) (opens in a new tab) — Allowable joist spans by species group, size, spacing and load (No. 2 grade, wet service, 10 psf dead load, L/Δ = 360), and maximum cantilevers by back span (L/Δ = 180 at the cantilever with a 220 lb point load on the end; interpolation allowed, extrapolation not). R507.7 limits joist spacing by decking thickness.
- ICC — 2024 International Residential Code, Chapter 5 Floors (opens in a new tab) — Table R507.6 carries the same span and cantilever values as the 2021 edition.
- American Wood Council — DCA 6, Prescriptive Residential Wood Deck Construction Guide (opens in a new tab) — Joist span table for a 40 psf live load (the same values as the IRC’s 40 psf rows) and how a joist span is measured.