Floor Joist Span Table Explained — IBC 2024 Worked Example: Sizing a 14 ft Joist Step by Step
1:56Published July 8, 2026Narrated, with captions and a full transcriptAlso on YouTube
Size a residential floor joist in StructSuite straight off the 2024 IBC prescriptive span tables — member type, loads, spacing, species and grade, then a pass/fail verification that names the exact table it read. A 14 ft span on a 2x8 fails on screen, and the fix takes one click.
Transcript and details
About this video
What you will see
- Choosing the member type: Floor Joist, Ceiling Joist, or Roof Joist & Rafter, one module covers all three
- Choosing the design basis: common lumber species off the IBC tables, or a Trus Joist TJI product off the Weyerhaeuser TJ-4000 tables
- Entering the span in feet and inches, then collapsing a finished step so its inputs read back as a single blue summary line
- The live load options exactly as the code splits them: residential sleeping areas at 30 psf and residential living areas at 40 psf, both at a deflection limit of L/360
- Dead load of 10 psf or 20 psf, a separate column in the IBC table, not a multiplier
- Joist spacing at 12, 16, 19.2 or 24 in o.c.
- Species and grade: Douglas Fir-Larch, Hem-Fir, Southern Pine or Spruce-Pine-Fir, in Select Structural, #1, #2 or #3
- Sizes 2x6 through 2x12
- Step 3, an optional Simpson Strong-Tie hanger selector for the joist end connection, shown then left switched off
- Step 4 returning the maximum table span against the span you entered, with a plain PASS or FAIL verdict naming the table
- A failure fixed the honest way: go back, pick the next deeper joist, and re-read the verification
- The result naming the table it used, 2024 IBC Table 2308.8.2.1(2), with links to 2024 IBC Chapter 23 and to the matching 2024 IRC tables on ICC Digital Codes
The joist in this example
14 ft span, residential living area: live load 40 psf at L/360, dead load 10 psf, joists at 16 in o.c., Douglas Fir-Larch #2. The first try, a 2x8, allows only 12 ft 7 in, short of the 14 ft span, so the check comes back FAIL. A 2x10 in the same row allows 15 ft 5 in, and the 14 ft span passes. Both values are read from 2024 IBC Table 2308.8.2.1(2), the 40 psf living-area floor joist table.
Codes referenced: 2024 IBC Chapter 23, Section 2308.8.2, Tables 2308.8.2.1(1) and 2308.8.2.1(2) for floor joists; Section 2308.11.1 for ceiling joists; Section 2308.11.2 for rafters; 2024 IRC Tables R502.3.1(1) and R502.3.1(2); Weyerhaeuser TJ-4000 for the TJI path.
Transcript
The narration word for word, 290 words, from the video's own captions. Select a time to play from there.
Floor Joist — 2024 IBC span check
0:02In this tutorial we'll size a residential floor joist in StructSuite, using the 2024 IBC prescriptive span tables. The same module also handles ceiling joists and rafters.
Add the Joist & Rafter module
0:13From the dashboard, add the Floor, Ceiling Joist and Rafter module. It opens with empty fields, ready for input. Step one. First choose the member type: floor joist, ceiling joist, or rafter. We'll design a floor joist.
Pick the design basis
0:26Next, the design basis: standard common lumber species, or an engineered Trus-Joist TJI product. We'll use common lumber. Then enter the joist span: fourteen feet.
Completed steps collapse to a blue summary
0:39When a step is complete, collapse it — and its inputs are captured in a blue summary line. Step two sets the loads and the section, all from simple code-based options.
Live load — 40 psf living area
0:49Pick the live load. Sleeping rooms are thirty psf; general living areas are forty. We'll use forty. Set the dead load to ten psf. Choose the joist spacing: sixteen inches on center.
Species & grade — DF-L #2
1:02Then the species and grade: Douglas Fir-Larch, Number 2. Finally the size. Let's first try a two-by-eight. Collapse step two, and again the choices are summarized.
Step 3 — Hanger Selector (optional)
1:13Step three is optional: enable it to size a Simpson hanger for the joist end connection. We'll leave it off. Step four checks the span against the IBC table. The two-by-eight allows only twelve foot seven — short of our fourteen feet. It's not satisfactory.
Not satisfactory — go back to Step 2
1:29That's fine — we go back to step two and pick a deeper joist. Select a two-by-ten. Back to verification. The two-by-ten allows fifteen foot five, so our fourteen-foot span is now satisfactory.
Cites the exact IBC table & sources
1:42The result names the exact 2024 IBC table used, and links the code references, so it's ready to defend in plan check. And that's a complete floor-joist check, ready to add to your report.