Quick span chart + selector
Floor Joist Span Chart
No. 2 solid-sawn lumber · 16 in. o.c. · L/360
Quick Answer: Maximum Floor Joist Spans
Default: 40 psf live + 10 psf dead load. Conservative values use the shortest span across the four listed species groups.
9 ft 1 in
maximum span 2×8
11 ft 10 in
maximum span 2×10
14 ft 0 in
maximum span 2×12
16 ft 6 in
maximum span
Need a size for a specific span? Enter the clear distance between support faces. The result updates instantly.
Your span result
2×10 is the smallest listed qualifying size
Recommended size 14 ft 0 in
Conservative max span 0 in
Span reserve 2
Qualifying sizes
For a 14 ft clear span, 2×10 is the smallest size that meets the default 40/10 psf condition across all four listed species groups at 16 in. o.c.
Use as a screening reference: verify the actual grade stamp, loads, bearing, restraint, holes/notches, adopted code, and project conditions before construction.
Measurement diagram
Measure Clear Span Face to Face
Do not enter overall board length or support centerline distance.
- Clear span
- 14 ft 0 in
- Listed depth
- 2×10
- Spacing
- 16 in. o.c.
- Grade
- No. 2
Bounded code excerpt
Floor Joist Span Reference Table
Showing 16 rows for 40/10 psf at 16 in. o.c., No. 2 grade.
Rows update with the selector. “Meets” compares each tabulated maximum span with your required clear span; equality passes. When all species are selected, the headline recommendation requires every listed species at that size to meet the span.
No verified joist in this bounded source scope meets the selected span. Use a deeper or engineered member, reduce spacing through a separately verified table, or obtain a structural design.
Scroll horizontally to view additional columns and vertically to view additional rows. Column headers remain visible while scrolling.
| Joist | Design condition | Span check | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Species group | Grade | Nominal size | Actual size | Spacing | Live/dead load | Deflection | Maximum clear span | Required span | Margin | Status |
| Douglas Fir–Larch | No. 2 | 2×6 | 1.5 × 5.5 in. | 16 in. | 40/10 psf | L/360 | 9 ft 9 in | 14 ft 0 in | −4 ft 3 in | Does not meet |
| Douglas Fir–Larch | No. 2 | 2×8 | 1.5 × 7.25 in. | 16 in. | 40/10 psf | L/360 | 12 ft 7 in | 14 ft 0 in | −1 ft 5 in | Does not meet |
| Douglas Fir–Larch | No. 2 | 2×10 | 1.5 × 9.25 in. | 16 in. | 40/10 psf | L/360 | 15 ft 5 in | 14 ft 0 in | 1 ft 5 in | Meets |
| Douglas Fir–Larch | No. 2 | 2×12 | 1.5 × 11.25 in. | 16 in. | 40/10 psf | L/360 | 17 ft 10 in | 14 ft 0 in | 3 ft 10 in | Meets |
| Hem–Fir | No. 2 | 2×6 | 1.5 × 5.5 in. | 16 in. | 40/10 psf | L/360 | 9 ft 1 in | 14 ft 0 in | −4 ft 11 in | Does not meet |
| Hem–Fir | No. 2 | 2×8 | 1.5 × 7.25 in. | 16 in. | 40/10 psf | L/360 | 12 ft 0 in | 14 ft 0 in | −2 ft 0 in | Does not meet |
| Hem–Fir | No. 2 | 2×10 | 1.5 × 9.25 in. | 16 in. | 40/10 psf | L/360 | 15 ft 2 in | 14 ft 0 in | 1 ft 2 in | Meets |
| Hem–Fir | No. 2 | 2×12 | 1.5 × 11.25 in. | 16 in. | 40/10 psf | L/360 | 17 ft 7 in | 14 ft 0 in | 3 ft 7 in | Meets |
| Southern Pine | No. 2 | 2×6 | 1.5 × 5.5 in. | 16 in. | 40/10 psf | L/360 | 9 ft 4 in | 14 ft 0 in | −4 ft 8 in | Does not meet |
| Southern Pine | No. 2 | 2×8 | 1.5 × 7.25 in. | 16 in. | 40/10 psf | L/360 | 11 ft 10 in | 14 ft 0 in | −2 ft 2 in | Does not meet |
| Southern Pine | No. 2 | 2×10 | 1.5 × 9.25 in. | 16 in. | 40/10 psf | L/360 | 14 ft 0 in | 14 ft 0 in | 0 in | Meets |
| Southern Pine | No. 2 | 2×12 | 1.5 × 11.25 in. | 16 in. | 40/10 psf | L/360 | 16 ft 6 in | 14 ft 0 in | 2 ft 6 in | Meets |
| Spruce–Pine–Fir | No. 2 | 2×6 | 1.5 × 5.5 in. | 16 in. | 40/10 psf | L/360 | 9 ft 4 in | 14 ft 0 in | −4 ft 8 in | Does not meet |
| Spruce–Pine–Fir | No. 2 | 2×8 | 1.5 × 7.25 in. | 16 in. | 40/10 psf | L/360 | 12 ft 3 in | 14 ft 0 in | −1 ft 9 in | Does not meet |
| Spruce–Pine–Fir | No. 2 | 2×10 | 1.5 × 9.25 in. | 16 in. | 40/10 psf | L/360 | 15 ft 5 in | 14 ft 0 in | 1 ft 5 in | Meets |
| Spruce–Pine–Fir | No. 2 | 2×12 | 1.5 × 11.25 in. | 16 in. | 40/10 psf | L/360 | 17 ft 10 in | 14 ft 0 in | 3 ft 10 in | Meets |
| Douglas Fir–Larch | No. 2 | 2×6 | 1.5 × 5.5 in. | 16 in. | 40/20 psf | L/360 | 9 ft 1 in | 14 ft 0 in | −4 ft 11 in | Does not meet |
| Douglas Fir–Larch | No. 2 | 2×8 | 1.5 × 7.25 in. | 16 in. | 40/20 psf | L/360 | 11 ft 6 in | 14 ft 0 in | −2 ft 6 in | Does not meet |
| Douglas Fir–Larch | No. 2 | 2×10 | 1.5 × 9.25 in. | 16 in. | 40/20 psf | L/360 | 14 ft 1 in | 14 ft 0 in | 1 in | Meets |
| Douglas Fir–Larch | No. 2 | 2×12 | 1.5 × 11.25 in. | 16 in. | 40/20 psf | L/360 | 16 ft 3 in | 14 ft 0 in | 2 ft 3 in | Meets |
| Hem–Fir | No. 2 | 2×6 | 1.5 × 5.5 in. | 16 in. | 40/20 psf | L/360 | 8 ft 11 in | 14 ft 0 in | −5 ft 1 in | Does not meet |
| Hem–Fir | No. 2 | 2×8 | 1.5 × 7.25 in. | 16 in. | 40/20 psf | L/360 | 11 ft 4 in | 14 ft 0 in | −2 ft 8 in | Does not meet |
| Hem–Fir | No. 2 | 2×10 | 1.5 × 9.25 in. | 16 in. | 40/20 psf | L/360 | 13 ft 10 in | 14 ft 0 in | −2 in | Does not meet |
| Hem–Fir | No. 2 | 2×12 | 1.5 × 11.25 in. | 16 in. | 40/20 psf | L/360 | 16 ft 1 in | 14 ft 0 in | 2 ft 1 in | Meets |
| Southern Pine | No. 2 | 2×6 | 1.5 × 5.5 in. | 16 in. | 40/20 psf | L/360 | 8 ft 6 in | 14 ft 0 in | −5 ft 6 in | Does not meet |
| Southern Pine | No. 2 | 2×8 | 1.5 × 7.25 in. | 16 in. | 40/20 psf | L/360 | 10 ft 10 in | 14 ft 0 in | −3 ft 2 in | Does not meet |
| Southern Pine | No. 2 | 2×10 | 1.5 × 9.25 in. | 16 in. | 40/20 psf | L/360 | 12 ft 10 in | 14 ft 0 in | −1 ft 2 in | Does not meet |
| Southern Pine | No. 2 | 2×12 | 1.5 × 11.25 in. | 16 in. | 40/20 psf | L/360 | 15 ft 1 in | 14 ft 0 in | 1 ft 1 in | Meets |
| Spruce–Pine–Fir | No. 2 | 2×6 | 1.5 × 5.5 in. | 16 in. | 40/20 psf | L/360 | 9 ft 1 in | 14 ft 0 in | −4 ft 11 in | Does not meet |
| Spruce–Pine–Fir | No. 2 | 2×8 | 1.5 × 7.25 in. | 16 in. | 40/20 psf | L/360 | 11 ft 6 in | 14 ft 0 in | −2 ft 6 in | Does not meet |
| Spruce–Pine–Fir | No. 2 | 2×10 | 1.5 × 9.25 in. | 16 in. | 40/20 psf | L/360 | 14 ft 1 in | 14 ft 0 in | 1 in | Meets |
| Spruce–Pine–Fir | No. 2 | 2×12 | 1.5 × 11.25 in. | 16 in. | 40/20 psf | L/360 | 16 ft 3 in | 14 ft 0 in | 2 ft 3 in | Meets |
Clear span is face-to-face between supports. This bounded table excludes other spacings and grades, sleeping-area loading, engineered products, cantilevers, multiple spans, concentrated loads, wet or treated lumber, damaged members, and local amendments.
Same-condition comparison
Maximum Span by Joist Size
Conservative maximum span by size for the active species scope.
When all species are selected, each bar uses the shortest listed maximum for that nominal size so the comparison does not overstate the weakest visible option.
How to Use the Floor Joist Span Chart
Reference basis: bounded 2024 model-code/AWC span data for No. 2 solid-sawn joists at 16 in. o.c. Verify the locally adopted code, lumber stamp, and project conditions before construction.
- Measure the clear distance from the inside face of one adequate support to the inside face of the other.
- Choose 10 psf dead load for a typical light floor assembly or 20 psf only when that verified preset represents the permanent assembly weight.
- Choose the species group printed on the lumber grade stamp, or leave “All species — conservative” selected so a recommended size must pass across every listed species group.
- Read the smallest listed qualifying depth, then verify every project condition excluded by this bounded chart.
Interpret the margin: A zero-inch margin passes the table boundary, but it provides no tabulated span reserve and does not address floor vibration, bearing, connections, or local amendments.
What Changes a Floor Joist’s Maximum Span
- Joist depth
- Deeper members are generally stiffer and can span farther under otherwise identical conditions.
- Spacing
- Wider on-center spacing assigns more tributary floor load to each joist and usually reduces allowable span.
- Species and grade
- Bending strength and modulus of elasticity vary with the species group, grade, and member size.
- Dead load
- Heavier finishes and assemblies reduce span when total-load strength or other checks govern.
Worked Floor Joist Selection Examples
14 ft living-area span
Use 40/10 psf, 16 in. o.c., No. 2 grade, and all species. The bounded rows show 2×10 as the smallest listed qualifying depth. Southern Pine reaches exactly 14 ft 0 in; the other listed species have larger margins. Final selection still depends on the actual stamp and project details.
14 ft with heavier dead load
Change the preset to 40/20 psf. Douglas Fir–Larch and Spruce–Pine–Fir 2×10 rows remain one inch above the requirement, while Hem–Fir and Southern Pine require a listed 2×12 in this bounded scope. This demonstrates why dead load cannot be assumed away.
Strength, Deflection, and Floor Stiffness
Allowable span is controlled by the most restrictive applicable check, not by nominal depth alone. The L/360 live-load deflection limit means the permitted live-load movement is the clear span divided by 360. At a 14 ft span, that ratio corresponds to 168/360 = 0.467 in. maximum live-load deflection under the table assumptions.
A joist can satisfy a strength and code deflection screen yet still feel bouncy to occupants. Vibration sensitivity, brittle finishes, partitions, concentrated loads, and owner performance expectations may justify a stiffer design.
When This Chart Does Not Apply
- Engineered I-joists, LVL or PSL members, open-web floor trusses, or steel joists
- Cantilevers, multiple spans, bearing partitions, point loads, unusual vibration criteria, or members supporting masonry
- Wet service, fire-retardant treatment, pressure treatment or incising, damaged lumber, or unverified grade stamps
- Joists with excessive holes or notches, inadequate bearing, missing lateral restraint, or connection deficiencies
- Any project whose adopted code, amendments, loads, or approved documents differ from this bounded source scope
Engineering References and Data Scope
Bounded 2024 code-table excerpt: No. 2 solid-sawn lumber, 16 in. o.c., 40 psf live load, 10 or 20 psf dead load, L/360.
The released rows are intentionally limited to common residential living-area conditions. Turn2Engineering calculates only the required-span comparison, margin, unit conversion, conservative all-species chart values, and first qualifying depth.
- 2024 International Building Code, Chapter 23—WoodTable 2308.8.2.1(2) context for conventional floor-joist spans; local residential adoption and amendments still control.
- AWC Tutorial for Understanding Loads and Using Span TablesSupports clear-span measurement, L/360 interpretation, strength and stiffness concepts, and the selection workflow.
- AWC STJR 2024 Span Tables for Joists and RaftersControlling expanded reference for species, grades, spacings, and load cases outside this bounded excerpt.
- 2024 International Residential Code, Chapter 5—FloorsResidential floor-framing context, limitations, and model-code provisions.
Dataset and Source-Check Details
- Dataset label
- 2024 bounded No. 2 floor-joist screening excerpt
- Canonical units
- Integer inches; exact 25.4 mm per inch conversion
- Source-controlled fields
- Species, grade, size, spacing, loads, maximum span
- Calculated fields
- Required span, margin, pass/fail, first qualifying depth
- Rights decision
- Limited transformed excerpt; no CSV or complete standards-table reproduction
- Publisher
- Turn2Engineering
Floor Joist Span FAQs
Under this page’s 40/10 psf, 16 in. o.c., No. 2 scope, the listed 2×8 maximum spans range from 11 ft 10 in to 12 ft 7 in depending on species. Other grades, spacings, loads, and service conditions require the corresponding verified table.
Not under this page’s 40/10 psf, 16 in. o.c., No. 2 rows: the longest listed 2×10 maximum is 15 ft 5 in. Different spacing, grade, species, or load conditions must be checked in the corresponding verified span table.
Measure the clear distance face to face between adequate supports. Do not use overall joist length, building width, or support centerline distance.
No. Exterior moisture exposure, treatment and incising, loads, cantilevers, connections, and governing deck provisions require separate data.
No. Engineered products require manufacturer-specific span tables, installation details, hole rules, and sometimes project-specific engineering.
Use the Result as a Screening Check
Match the grade stamp and species, use the correct clear span and loads, and treat the displayed size as the smallest listed option within this bounded table—not as a universal construction approval. Move to the expanded AWC tables or a structural design whenever the project falls outside the stated scope.