Feature
A 2x8 Douglas Fir-Larch or Southern Pine joist at Select Structural grade and 12-inch spacing tops out at 16'-6" under a 30 psf live load.
This sortable, filterable table lists max 2x8 joist spans for four species and every grade at 12, 16, 19.2, and 24 inches on-center, at 30 and 40 psf live load.
By Errol Nakamura · filed · revised — · 1 min
Codes are local and manufacturers publish their own limits. Confirm any figure here against your local authority and the printed instructions on the bag, box or panel before you buy or build.
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. Filter by species, grade, and live load, or sort any column, to find the exact span for your job.
| 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" |
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.
Ran 10+ searches (AWC/Southern Pine Council span tables, IRC Table R502.3.1(1) and (2) by keyword and by edition year, site-restricted searches for government PDF reproductions). WebFetch's built-in AI summarizer could not reliably read table data straight out of PDF binaries (it either refused or returned numbers with rows/columns visibly scrambled, e.g. non-monotonic spans as spacing widened) — confirmed this by having it AI-summarize the Southern Pine Council PDF via the r.jina.ai reader proxy and finding scrambled, physically-impossible values (spans increasing at wider spacing), which were discarded. The reliable path was: WebFetch a PDF, note when it says the binary was saved locally, then Read that saved PDF directly, which correctly parsed every table (verified internally for monotonicity and against a second document). Mid-research, cross-checking a 2012-vintage city reproduction (Republic, MO) against a current up.codes display surfaced a real conflict for Southern Pine; this led to discovering and confirming, via ICC's own April 2013 legislative amendment document, that Southern Pine reference design values were reduced industry-wide in 2013 (Southern Pine Inspection Bureau re-testing), while a separate, smaller Douglas Fir-Larch revision happened later. Both changes were confirmed against multiple independent, dated, government-published PDFs before being used, rather than trusting any single source or AI table summary.
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.