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A 2x8 floor joist’s maximum span depends on species, grade, spacing, and live load, and the top figure in this table is 16’-6” for Douglas Fir-Larch or Southern Pine at Select/Dense Select Structural grade, 12 inches on-center, under a 30 psf sleeping-area load. Spans shrink as spacing widens, as grade drops, and as the live load moves from 30 psf (bedrooms and attics) to 40 psf (living areas). The table below covers all 128 combinations across Douglas Fir-Larch, Hem-Fir, Southern Pine, and Spruce-Pine-Fir.
Pick your configuration. Choose species, grade, live load and spacing to see the matching span and its assumptions. Open the full table to compare or sort all 128 setups.
Find Your 2×8 Joist Span
Choose species, grade, live load and spacing to get one span. All rows assume 10 psf dead load and L/360 live-load deflection.
Open This Row’s Source TableReference spans for sawn-lumber floor joists, measured between bearing faces. Confirm the adopted code and your actual loads before using a span for construction.
View Matching Rows In The Full Table
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| Species | Grade | Spacing (o.c.) | Live Load | Dead Load | Max Span |
|---|---|---|---|---|---|
| Douglas Fir-Larch | Select Structural | 12 | 30 | 10 | 16'-6" |
| Douglas Fir-Larch | Select Structural | 16 | 30 | 10 | 15'-0" |
| Douglas Fir-Larch | Select Structural | 19.2 | 30 | 10 | 14'-1" |
| Douglas Fir-Larch | Select Structural | 24 | 30 | 10 | 13'-1" |
| Douglas Fir-Larch | Select Structural | 12 | 40 | 10 | 15'-0" |
| Douglas Fir-Larch | Select Structural | 16 | 40 | 10 | 13'-7" |
| Douglas Fir-Larch | Select Structural | 19.2 | 40 | 10 | 12'-10" |
| Douglas Fir-Larch | Select Structural | 24 | 40 | 10 | 11'-11" |
| Douglas Fir-Larch | No.1 | 12 | 30 | 10 | 15'-10" |
| Douglas Fir-Larch | No.1 | 16 | 30 | 10 | 14'-5" |
| Douglas Fir-Larch | No.1 | 19.2 | 30 | 10 | 13'-7" |
| Douglas Fir-Larch | No.1 | 24 | 30 | 10 | 12'-4" |
| Douglas Fir-Larch | No.1 | 12 | 40 | 10 | 14'-5" |
| Douglas Fir-Larch | No.1 | 16 | 40 | 10 | 13'-1" |
| Douglas Fir-Larch | No.1 | 19.2 | 40 | 10 | 12'-4" |
| Douglas Fir-Larch | No.1 | 24 | 40 | 10 | 11'-0" |
| Douglas Fir-Larch | No.2 | 12 | 30 | 10 | 15'-7" |
| Douglas Fir-Larch | No.2 | 16 | 30 | 10 | 14'-2" |
| Douglas Fir-Larch | No.2 | 19.2 | 30 | 10 | 13'-0" |
| Douglas Fir-Larch | No.2 | 24 | 30 | 10 | 11'-8" |
| Douglas Fir-Larch | No.2 | 12 | 40 | 10 | 14'-2" |
| Douglas Fir-Larch | No.2 | 16 | 40 | 10 | 12'-9" |
| Douglas Fir-Larch | No.2 | 19.2 | 40 | 10 | 11'-8" |
| Douglas Fir-Larch | No.2 | 24 | 40 | 10 | 10'-5" |
| Douglas Fir-Larch | No.3 | 12 | 30 | 10 | 12'-7" |
| Douglas Fir-Larch | No.3 | 16 | 30 | 10 | 10'-11" |
| Douglas Fir-Larch | No.3 | 19.2 | 30 | 10 | 10'-0" |
| Douglas Fir-Larch | No.3 | 24 | 30 | 10 | 8'-11" |
| Douglas Fir-Larch | No.3 | 12 | 40 | 10 | 11'-3" |
| Douglas Fir-Larch | No.3 | 16 | 40 | 10 | 9'-9" |
| Douglas Fir-Larch | No.3 | 19.2 | 40 | 10 | 8'-11" |
| Douglas Fir-Larch | No.3 | 24 | 40 | 10 | 8'-0" |
| Hem-Fir | Select Structural | 12 | 30 | 10 | 15'-7" |
| Hem-Fir | Select Structural | 16 | 30 | 10 | 14'-2" |
| Hem-Fir | Select Structural | 19.2 | 30 | 10 | 13'-4" |
| Hem-Fir | Select Structural | 24 | 30 | 10 | 12'-4" |
| Hem-Fir | Select Structural | 12 | 40 | 10 | 14'-2" |
| Hem-Fir | Select Structural | 16 | 40 | 10 | 12'-10" |
| Hem-Fir | Select Structural | 19.2 | 40 | 10 | 12'-1" |
| Hem-Fir | Select Structural | 24 | 40 | 10 | 11'-3" |
| Hem-Fir | No.1 | 12 | 30 | 10 | 15'-3" |
| Hem-Fir | No.1 | 16 | 30 | 10 | 13'-10" |
| Hem-Fir | No.1 | 19.2 | 30 | 10 | 13'-0" |
| Hem-Fir | No.1 | 24 | 30 | 10 | 12'-0" |
| Hem-Fir | No.1 | 12 | 40 | 10 | 13'-10" |
| Hem-Fir | No.1 | 16 | 40 | 10 | 12'-7" |
| Hem-Fir | No.1 | 19.2 | 40 | 10 | 11'-10" |
| Hem-Fir | No.1 | 24 | 40 | 10 | 10'-10" |
| Hem-Fir | No.2 | 12 | 30 | 10 | 14'-6" |
| Hem-Fir | No.2 | 16 | 30 | 10 | 13'-2" |
| Hem-Fir | No.2 | 19.2 | 30 | 10 | 12'-5" |
| Hem-Fir | No.2 | 24 | 30 | 10 | 11'-4" |
| Hem-Fir | No.2 | 12 | 40 | 10 | 13'-2" |
| Hem-Fir | No.2 | 16 | 40 | 10 | 12'-0" |
| Hem-Fir | No.2 | 19.2 | 40 | 10 | 11'-3" |
| Hem-Fir | No.2 | 24 | 40 | 10 | 10'-2" |
| Hem-Fir | No.3 | 12 | 30 | 10 | 12'-4" |
| Hem-Fir | No.3 | 16 | 30 | 10 | 10'-8" |
| Hem-Fir | No.3 | 19.2 | 30 | 10 | 9'-9" |
| Hem-Fir | No.3 | 24 | 30 | 10 | 8'-8" |
| Hem-Fir | No.3 | 12 | 40 | 10 | 11'-0" |
| Hem-Fir | No.3 | 16 | 40 | 10 | 9'-6" |
| Hem-Fir | No.3 | 19.2 | 40 | 10 | 8'-8" |
| Hem-Fir | No.3 | 24 | 40 | 10 | 7'-9" |
| Southern Pine | Dense Select Structural | 12 | 30 | 10 | 16'-6" |
| Southern Pine | Dense Select Structural | 16 | 30 | 10 | 15'-0" |
| Southern Pine | Dense Select Structural | 19.2 | 30 | 10 | 14'-1" |
| Southern Pine | Dense Select Structural | 24 | 30 | 10 | 13'-1" |
| Southern Pine | Dense Select Structural | 12 | 40 | 10 | 15'-0" |
| Southern Pine | Dense Select Structural | 16 | 40 | 10 | 13'-7" |
| Southern Pine | Dense Select Structural | 19.2 | 40 | 10 | 12'-10" |
| Southern Pine | Dense Select Structural | 24 | 40 | 10 | 11'-11" |
| Southern Pine | No.1 | 12 | 30 | 10 | 15'-7" |
| Southern Pine | No.1 | 16 | 30 | 10 | 14'-2" |
| Southern Pine | No.1 | 19.2 | 30 | 10 | 13'-4" |
| Southern Pine | No.1 | 24 | 30 | 10 | 12'-4" |
| Southern Pine | No.1 | 12 | 40 | 10 | 14'-2" |
| Southern Pine | No.1 | 16 | 40 | 10 | 12'-10" |
| Southern Pine | No.1 | 19.2 | 40 | 10 | 12'-1" |
| Southern Pine | No.1 | 24 | 40 | 10 | 11'-3" |
| Southern Pine | No.2 | 12 | 30 | 10 | 14'-11" |
| Southern Pine | No.2 | 16 | 30 | 10 | 13'-3" |
| Southern Pine | No.2 | 19.2 | 30 | 10 | 12'-1" |
| Southern Pine | No.2 | 24 | 30 | 10 | 10'-10" |
| Southern Pine | No.2 | 12 | 40 | 10 | 13'-6" |
| Southern Pine | No.2 | 16 | 40 | 10 | 11'-10" |
| Southern Pine | No.2 | 19.2 | 40 | 10 | 10'-10" |
| Southern Pine | No.2 | 24 | 40 | 10 | 9'-8" |
| Southern Pine | No.3 | 12 | 30 | 10 | 11'-6" |
| Southern Pine | No.3 | 16 | 30 | 10 | 10'-0" |
| Southern Pine | No.3 | 19.2 | 30 | 10 | 9'-1" |
| Southern Pine | No.3 | 24 | 30 | 10 | 8'-2" |
| Southern Pine | No.3 | 12 | 40 | 10 | 10'-3" |
| Southern Pine | No.3 | 16 | 40 | 10 | 8'-11" |
| Southern Pine | No.3 | 19.2 | 40 | 10 | 8'-2" |
| Southern Pine | No.3 | 24 | 40 | 10 | 7'-3" |
| Spruce-Pine-Fir | Select Structural | 12 | 30 | 10 | 15'-3" |
| Spruce-Pine-Fir | Select Structural | 16 | 30 | 10 | 13'-10" |
| Spruce-Pine-Fir | Select Structural | 19.2 | 30 | 10 | 13'-0" |
| Spruce-Pine-Fir | Select Structural | 24 | 30 | 10 | 12'-1" |
| Spruce-Pine-Fir | Select Structural | 12 | 40 | 10 | 13'-10" |
| Spruce-Pine-Fir | Select Structural | 16 | 40 | 10 | 12'-7" |
| Spruce-Pine-Fir | Select Structural | 19.2 | 40 | 10 | 11'-10" |
| Spruce-Pine-Fir | Select Structural | 24 | 40 | 10 | 11'-0" |
| Spruce-Pine-Fir | No.1 | 12 | 30 | 10 | 14'-11" |
| Spruce-Pine-Fir | No.1 | 16 | 30 | 10 | 13'-6" |
| Spruce-Pine-Fir | No.1 | 19.2 | 30 | 10 | 12'-9" |
| Spruce-Pine-Fir | No.1 | 24 | 30 | 10 | 11'-6" |
| Spruce-Pine-Fir | No.1 | 12 | 40 | 10 | 13'-6" |
| Spruce-Pine-Fir | No.1 | 16 | 40 | 10 | 12'-3" |
| Spruce-Pine-Fir | No.1 | 19.2 | 40 | 10 | 11'-6" |
| Spruce-Pine-Fir | No.1 | 24 | 40 | 10 | 10'-3" |
| Spruce-Pine-Fir | No.2 | 12 | 30 | 10 | 14'-11" |
| Spruce-Pine-Fir | No.2 | 16 | 30 | 10 | 13'-6" |
| Spruce-Pine-Fir | No.2 | 19.2 | 30 | 10 | 12'-9" |
| Spruce-Pine-Fir | No.2 | 24 | 30 | 10 | 11'-6" |
| Spruce-Pine-Fir | No.2 | 12 | 40 | 10 | 13'-6" |
| Spruce-Pine-Fir | No.2 | 16 | 40 | 10 | 12'-3" |
| Spruce-Pine-Fir | No.2 | 19.2 | 40 | 10 | 11'-6" |
| Spruce-Pine-Fir | No.2 | 24 | 40 | 10 | 10'-3" |
| Spruce-Pine-Fir | No.3 | 12 | 30 | 10 | 12'-4" |
| Spruce-Pine-Fir | No.3 | 16 | 30 | 10 | 10'-8" |
| Spruce-Pine-Fir | No.3 | 19.2 | 30 | 10 | 9'-9" |
| Spruce-Pine-Fir | No.3 | 24 | 30 | 10 | 8'-8" |
| Spruce-Pine-Fir | No.3 | 12 | 40 | 10 | 11'-0" |
| Spruce-Pine-Fir | No.3 | 16 | 40 | 10 | 9'-6" |
| Spruce-Pine-Fir | No.3 | 19.2 | 40 | 10 | 8'-8" |
| Spruce-Pine-Fir | No.3 | 24 | 40 | 10 | 7'-9" |
See How Spacing Changes The Span
No. 2 grade · 40 psf live load · 10 psf dead load
Assumptions, Sources And Gaps
Maximum clear spans (inside face of bearing to inside face of bearing) for nominal 2x8 (actual 1-1/2 x 7-1/4 in.) sawn-lumber floor joists, repetitive-member use (3+ joists spaced not more than 24 in. o.c.), Allowable Stress Design. 30 psf live load = residential sleeping rooms/habitable attics per IRC Table R502.3.1(1); 40 psf live load = residential living areas per IRC Table R502.3.1(2). Dead load = 10 psf in all rows (the tables also publish a 20 psf dead-load column, not reproduced here). Deflection limit = L/360 (live load only), the standard IRC/AWC floor-joist limit. Southern Pine values reflect the reference design values effective June 1, 2013 (a ~5-10% span reduction from the pre-2013 IRC table for this species only, following updated full-size lumber testing by the Southern Pine Inspection Bureau); Douglas Fir-Larch values reflect a later, smaller upward revision that current (2022-2024-era) code reproductions show but the original 2012 IRC printing does not. Hem-Fir and Spruce-Pine-Fir values are unchanged from the original 2012 IRC table and were confirmed identical in a current (2024) government reproduction. 'Select Structural'/'Dense Select Structural' is the top visual grade; No.1/No.2/No.3 are progressively lower visual grades. No.2 is the grade most commonly stocked and used for general residential framing when a grade stamp isn't specified.
- Maximum Spans: Southern Pine Joists & Rafters (2013 Edition)Southern Forest Products Association / Southern Pine Council · primaryTables 1 (30 psf) and 2 (40 psf) floor joists, 10 psf dead load, L/360, read directly from the PDF (page images), giving Dense Select Structural/No.1/No.2/No.3 2x8 spans for Southern Pine. States these reflect design values effective June 1, 2013. Cross-verified cell-for-cell against the ICC's own April 2013 legislative amendment (below).
- April 2013 Amendments – Legislative Format, Floors (Tables R502.3.1(1) and R502.3.1(2))North Carolina Office of State Fire Marshal (hosting the official ICC/IRC amendment redline) · primaryShows the original 2003/2006/2009 IRC Table R502.3.1(1) and (2) with the April 2013 Southern-Pine-only redline (strikethrough = old value, underline = new/current value). Confirms Douglas Fir-Larch, Hem-Fir and Spruce-Pine-Fir rows were NOT changed by this amendment – only Southern Pine values were reduced. This resolved a discrepancy between an older reproduction (Republic, MO) and current sources.
- Span Table: Floor Joist Spans for Common Lumber Species, R502.3.1(2), Live Load = 40 lbsPacific County, WA Department of Community Development · secondaryCurrent (dated 7/23/2024) literal reproduction of the 40 psf living-area table for Douglas Fir-Larch and Hem-Fir, all 4 grades, 10 psf dead load, all spacings. Used to establish the current (post-2015) Douglas Fir-Larch values, which are slightly higher than the original 2012 IRC printing; confirmed Hem-Fir is unchanged.
- Residential Span Tables – Floor Joists, 2022 CRC Table R502.3.1(2), Douglas Fir Larch #2 or BetterCity of Sacramento Community Development Department · secondaryIndependent current (rev. 1-01-2023) reproduction that matches Pacific County's Douglas Fir-Larch No.2 40-psf spans exactly (e.g. 2x8 @16" o.c. = 12'-9" in both), corroborating the current DF-L values against a second independent government source.
- Floor Joist Spans – Residential Sleeping Areas / Residential Living Areas (2012 IRC Table R502.3.1(1) and (2))City of Republic, MO Community Development · secondaryFull literal reproduction of the original 2012 IRC tables for all four species/all four grades/all spacings/10 & 20 psf dead load. Used for Hem-Fir and Spruce-Pine-Fir (confirmed by the ICC amendment document and Pacific County cross-check to be unchanged from 2012 to today). NOT used for Southern Pine (superseded by the 2013 design-value reduction) or for Douglas Fir-Larch (superseded by a later revision). Companion living-areas table: https://www.republicmo.com/DocumentCenter/View/138/Floor-Joist---Living-Areas
- R502.3.1 Sleeping Areas and Attic Joists (current IRC, Table R502.3.1(1))UpCodes (current-edition IRC viewer, spot-checked against 2024 IRC text) · secondaryUsed for current Douglas Fir-Larch 30-psf sleeping-area spans (SS/No.1/No.2/No.3, all spacings). WebFetch's AI extraction of this page was cross-validated: its Southern Pine No.2 figures matched the SFPA 2013 PDF exactly cell-for-cell, and its Douglas Fir-Larch shift vs. the 2012 baseline matches the same direction/magnitude confirmed by the literal Pacific County 40-psf table.
Spans are transcribed from the cited code tables and dated reproductions. Southern Pine uses the revised 2013 design values; Douglas Fir-Larch uses later reproductions. The source notes identify the edition and checks for each species.
Spruce-Pine-Fir 40 psf (living-area) values are sourced from the original 2012 IRC table only; we found no independent, dated post-2015 government reproduction to literally re-confirm them (unlike Douglas Fir-Larch and Hem-Fir, which were each cross-checked against a currently-dated source). They are used because the ICC's own 2013 amendment document explicitly shows Spruce-Pine-Fir as unmodified, and no other revision to this species was found in searches — but this is one level less directly verified than the other three species. We did not find span data for grades finer than No.1/No.2/No.3/Select Structural (e.g. Southern Pine's MSR/MEL machine-graded classes, or wet-service/pressure-treated conditions) since the task scope was the standard IRC common-species table; those exist in the Southern Pine Council PDF (Tables 8-14) if needed later. The 20 psf dead-load column (also published in every source table) was intentionally omitted to keep the table to the single 10 psf assumption the task specified.