Wood Joist Span Table

Lookup typical residential wood joist spans by species group, nominal size, and on-center spacing.

Author

Woodworking editorial contributor

Polish biostatistician at the University of Warsaw, advancing Bayesian methods for clinical trial design

Reviewed by

Woodworking content reviewer

Nigerian legal scholar with an SJD from Yale, focused on international trade law and African continental free trade agreements

Last updatedFebruary 22, 2026

PublishedFebruary 22, 2026

Reference Values

Browse 45 reference values with individual detail pages for quick lookup.

Browse all reference values

Joist Span Lookup

Choose species group, joist size, and spacing to estimate maximum span.

Estimated Maximum Span

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Reference Table

Use this complete table for quick lookup and internal linking to specific value pages.

Wood Joist Span Table Reference
Species Group	Joist Size	Spacing (in o.c.)	Max Span
SPF No.2	2 × 6	12	12 ft 2 in
SPF No.2	2 × 6	16	10 ft 11 in
SPF No.2	2 × 6	24	8 ft 11 in
SPF No.2	2 × 8	12	15 ft 10 in
SPF No.2	2 × 8	16	14 ft 1 in
SPF No.2	2 × 8	24	11 ft 7 in
SPF No.2	2 × 10	12	19 ft 3 in
SPF No.2	2 × 10	16	17 ft 2 in
SPF No.2	2 × 10	24	14 ft 1 in
SPF No.2	2 × 12	12	22 ft 2 in
SPF No.2	2 × 12	16	19 ft 10 in
SPF No.2	2 × 12	24	16 ft 3 in
SPF No.2	2 × 14	12	24 ft 6 in
SPF No.2	2 × 14	16	21 ft 11 in
SPF No.2	2 × 14	24	17 ft 11 in
Douglas Fir-Larch No.2	2 × 6	12	12 ft 9 in
Douglas Fir-Larch No.2	2 × 6	16	11 ft 5 in
Douglas Fir-Larch No.2	2 × 6	24	9 ft 4 in
Douglas Fir-Larch No.2	2 × 8	12	16 ft 6 in
Douglas Fir-Larch No.2	2 × 8	16	14 ft 8 in
Douglas Fir-Larch No.2	2 × 8	24	12 ft 1 in
Douglas Fir-Larch No.2	2 × 10	12	20 ft 2 in
Douglas Fir-Larch No.2	2 × 10	16	18 ft 0 in
Douglas Fir-Larch No.2	2 × 10	24	14 ft 9 in
Douglas Fir-Larch No.2	2 × 12	12	23 ft 2 in
Douglas Fir-Larch No.2	2 × 12	16	20 ft 8 in
Douglas Fir-Larch No.2	2 × 12	24	17 ft 0 in
Douglas Fir-Larch No.2	2 × 14	12	25 ft 6 in
Douglas Fir-Larch No.2	2 × 14	16	22 ft 10 in
Douglas Fir-Larch No.2	2 × 14	24	18 ft 8 in
Southern Pine No.2	2 × 6	12	13 ft 3 in
Southern Pine No.2	2 × 6	16	11 ft 10 in
Southern Pine No.2	2 × 6	24	9 ft 8 in
Southern Pine No.2	2 × 8	12	16 ft 11 in
Southern Pine No.2	2 × 8	16	15 ft 1 in
Southern Pine No.2	2 × 8	24	12 ft 5 in
Southern Pine No.2	2 × 10	12	20 ft 9 in
Southern Pine No.2	2 × 10	16	18 ft 6 in
Southern Pine No.2	2 × 10	24	15 ft 2 in
Southern Pine No.2	2 × 12	12	23 ft 10 in
Southern Pine No.2	2 × 12	16	21 ft 4 in
Southern Pine No.2	2 × 12	24	17 ft 6 in
Southern Pine No.2	2 × 14	12	26 ft 2 in
Southern Pine No.2	2 × 14	16	23 ft 5 in
Southern Pine No.2	2 × 14	24	19 ft 2 in

Frequently Asked Questions

Common questions about Wood Joist Span Table, formulas, and typical use cases.

What loads are these span values based on?

These values are typical references based on common residential assumptions around 40 psf live load and 10 psf dead load.

Why does spacing change allowable span?

Wider on-center spacing means each joist supports more floor area, which reduces allowable span for a given size and species.

Can I use this instead of local building code tables?

Use this as a planning tool only. Final joist spans must follow your local code, species grade stamp, and project loading conditions.

Why are species groups separated?

Different wood species have different strength and stiffness properties, so allowable spans differ even with the same joist size.

Methodology and Review

This page combines a live calculator, precomputed reference values, and FAQ content from the same conversion definition to reduce mismatch between calculator output and lookup tables.

Editorial metadata (author, reviewer, and update date) is rendered on the page and in structured data. See our editorial policy, review process, and corrections policy.

For compliance-sensitive work, verify final values against project requirements, governing standards, and manufacturer documentation.