A wood I-beam, properly called an I-joist, is an engineered joist with an OSB web glued between two flanges of laminated veneer lumber or solid sawn lumber. It spans further than dimensional lumber of the same depth, weighs less and stays straight. Sizes are set by the manufacturer, not by a general standard, so this chart uses the most widely stocked series in North America.
Wood I-Beam (I-Joist) Sizes
Depths, flange widths, web thicknesses and weights for Trus Joist TJI joists. A 16 ft joist weight is included so you can plan handling.
| Depth | Series | Flange width | Web thickness | Weight (lb/ft) | 16 ft piece (lb) |
|---|---|---|---|---|---|
| 9 1/2″ | TJI 110 | 1-3/4″ | 3/8″ | 2.3 | 37 |
| 9 1/2″ | TJI 210 | 2-1/16″ | 3/8″ | 2.6 | 42 |
| 9 1/2″ | TJI 230 | 2-5/16″ | 3/8″ | 2.7 | 43 |
| 11 7/8″ | TJI 110 | 1-3/4″ | 3/8″ | 2.5 | 40 |
| 11 7/8″ | TJI 210 | 2-1/16″ | 3/8″ | 2.8 | 45 |
| 11 7/8″ | TJI 230 | 2-5/16″ | 3/8″ | 3 | 48 |
| 11 7/8″ | TJI 360 | 2-5/16″ | 3/8″ | 3 | 48 |
| 11 7/8″ | TJI 560 | 3-1/2″ | 7/16″ | 4 | 64 |
| 14″ | TJI 110 | 1-3/4″ | 3/8″ | 2.8 | 45 |
| 14″ | TJI 210 | 2-1/16″ | 3/8″ | 3.1 | 50 |
| 14″ | TJI 230 | 2-5/16″ | 3/8″ | 3.3 | 53 |
| 14″ | TJI 360 | 2-5/16″ | 3/8″ | 3.3 | 53 |
| 14″ | TJI 560 | 3-1/2″ | 7/16″ | 4.2 | 67 |
| 16″ | TJI 110 | 1-3/4″ | 3/8″ | 3 | 48 |
| 16″ | TJI 210 | 2-1/16″ | 3/8″ | 3.3 | 53 |
| 16″ | TJI 230 | 2-5/16″ | 3/8″ | 3.5 | 56 |
| 16″ | TJI 360 | 2-5/16″ | 3/8″ | 3.5 | 56 |
| 16″ | TJI 560 | 3-1/2″ | 7/16″ | 4.5 | 72 |
| 18″ | TJI 360 | 2-5/16″ | 3/8″ | 3.7 | 59 |
| 18″ | TJI 560 | 3-1/2″ | 7/16″ | 4.8 | 77 |
| 18″ | TJI 560D | 3-1/2″ | 7/16″ | 5 | 80 |
| 20″ | TJI 360 | 2-5/16″ | 3/8″ | 4 | 64 |
| 20″ | TJI 560 | 3-1/2″ | 7/16″ | 5.1 | 82 |
| 20″ | TJI 560D | 3-1/2″ | 7/16″ | 5.3 | 85 |
| 22″ | TJI 560D | 3-1/2″ | 7/16″ | 5.6 | 90 |
| 24″ | TJI 560D | 3-1/2″ | 7/16″ | 5.8 | 93 |
Source: Weyerhaeuser Trus Joist TJI Joist Specifier’s Guide TJ-4000, July 2025 (weyerhaeuser.com). Flange thickness varies by series, from 1-1/4 in on the lighter joists to 1-1/2 in on the 560 series. 22 in and 24 in depths are only available in some regions.
How I-Joist Sizes Are Written
A size such as TJI 210 11-7/8 gives the series and the depth. The series number tells you the flange size and strength: 110 has a 1-3/4 in flange, 210 has 2-1/16 in, 230 and 360 have 2-5/16 in, and 560 has 3-1/2 in. Deeper and wider means longer spans and heavier loads. Common depths are 9-1/2, 11-7/8, 14 and 16 in, which match standard floor framing.
Spans
Span depends on depth, series, joist spacing, the loads and the deflection limit you design to, so there is no single span number for a size. Manufacturers publish span tables in their specifier guides, and those tables are what the building department will expect to see. As a rough orientation only, 11-7/8 in joists at 16 in on center commonly carry residential floors in the high teens of feet, but check the actual table for your series, spacing and load before you order anything.
Other Brands
Trus Joist TJI is the best known name, but Boise Cascade BCI and AJS, LP SolidStart, Nordic and Pacific Woodtech all make equivalent I-joists. Depths match across brands, and flange widths are similar, but the allowable spans, hole charts and hangers are brand specific. Never substitute one brand’s joist into another brand’s span table.
Holes and Notches
The web can be drilled, but only in the sizes and locations the manufacturer’s hole chart allows, and the flanges must never be cut, notched or drilled. Cutting a flange destroys the joist. Factory knockouts in the web are provided for small wiring runs.
Wood I-Beam Cost
I-joists are priced per linear foot and sit between dimensional lumber and LVL. Published 2026 US figures put engineered beams generally at about $3 to $34 per linear foot depending on type and size, with LVL around $3 to $12 per foot; I-joists normally fall at the lower end because they use less material than a solid LVL of the same depth. Price moves with depth, series and length, and lumber yards quote by the job.
Cost ranges are from HomeGuide’s 2026 beam cost guide (homeguide.com), checked September 2026. Get a local quote for your depth, series and quantity.
Wood I-Beam vs Steel
I-joists are for repetitive framing: floors and roofs at 12 to 24 in on center. Where a single member has to carry a wall or a long clear span, the choice is usually LVL, glulam or steel. Steel is heavier to handle but much shallower for the same job, which matters when headroom is tight. Steel sizes and prices are in the steel I-beam cost guide and the wide flange beam sizes chart.
Wood I-Beam FAQ
What sizes do wood I-beams come in?
Standard depths are 9-1/2, 11-7/8, 14 and 16 in, with 18, 20, 22 and 24 in available in the deeper series. Flange widths run from 1-3/4 to 3-1/2 in. Lengths are made up to 60 ft in 1 ft increments.
How much does an I-joist weigh?
From about 2.3 lb/ft for a 9-1/2 in TJI 110 to about 5.8 lb/ft for a 24 in TJI 560D. A 16 ft length of the lightest joist weighs under 40 lb, which is why one person can carry them.
Can I use an I-joist outdoors?
No. These joists are for dry-use applications. Exposure to weather during construction should be limited, and permanent wet or exposed locations need a different product.
Are wood I-beams stronger than solid lumber?
For the same depth they usually span further and carry more, because the flanges are engineered lumber and the material is placed where it works hardest. They are also far more consistent than sawn lumber.
This page is reference information only and is not engineering advice. Sizing, rigging and load capacity decisions need a qualified engineer. Full disclaimer.