First time framing a floor with TJI I-joists instead of sawn lumber.

When framing a floor with TJI I-joists instead of sawn lumber, there are several key differences and important safety considerations to address:

Support and Handling:

• TJI I-joists are lighter but more susceptible to damage. Always support them every 4 feet during installation to prevent web buckling or flange damage.
• Never let I-joists span unsupported between walls or floors—they can sag or twist.

Installation Differences:

• No notching or drilling in the web except as specified by the manufacturer. The structural integrity depends on the engineered design.
• Use approved hangers rated for I-joists—sawn lumber hangers won’t work. Install according to the hanger manufacturer’s specs (typically requires 10d or 16d nails in specific patterns).
• Leveling is critical—shim between the hanger and joist if needed. Uneven bearing can cause twisting.

Blocking and Bracing:

• Install solid blocking at bearing points and mid-span where required by local code or engineering plans.
• Use lateral bridging (often sold as TJI brand bridging) every 8–10 feet to prevent twisting.

Safety and Code Compliance:

• Always refer to the manufacturer’s installation guide (e.g., Weyerhaeuser, Georgia-Pacific). These are code-referenced documents.
• Check local building codes—some jurisdictions require a registered design professional to approve I-joist floor systems.
• Avoid exposing TJI edges to moisture—swelling of the OSB web can compromise strength.

Bottom Line: If you're unfamiliar with I-joist installation, consider having an experienced framer or engineer review your plans. Improper installation can lead to floor bounce, structural failure, or code violations.

Let me know the brand and span you're working with—I can help you find the specific installation requirements.

Key Differences for TJI I-Joist Floor Framing:

1. Hangers & Connections (Critical)

• Use specific I-joist hangers (face-mount or top-flange) rated for the flange width. Never use standard sawn lumber hangers—they crush the thin flanges.
• Fill all nail holes (round and triangle/diamond) unless manufacturer specs say otherwise. Use specified nails (typically 10d x 1.5" or 16d sinkers); gun nails often too short.
• Web stiffeners required at:
• All bearing locations (walls, beams, hangers) per mfr specs.
• Concentrated loads.
• Hangers without top-flange bearing.
• Cut stiffeners from OSB/plywood per mfr depth/width table; nail per schedule.

2. Handling & Cutting

• Never cut, notch, or drill flanges. Period.
• Web holes only: Follow manufacturer’s hole chart (distance from bearing, max diameter, spacing). Typically no holes in first/last 12" of span.
• Protect from weather: Store flat, covered, off ground. Wet OSB webs swell/delaminate.

3. Bearing & Rim Board

• Min. bearing: 1¾" on wood/metal, 3" on concrete/masonry (IRC R502.1.2 / mfr specs).
• Rim Board: Must use structural rim board (1¼" min. OSB/ LVL/ LSL) matching joist depth. Sawn lumber rim shrinks → squeaks/gaps. Nail rim to joist webs per mfr schedule (typically 8d/10d @ 6" OC).

4. Bracing (IRC R502.1.2 / Mfr Specs)

• Blocking panels or x-bracing at max 8' OC along span.
• Rim board acts as end blocking.
• Squash blocks under point loads (posts, bearing walls) – 2x4/2x6 vertical blocks beside joist, tight to subfloor & plate.

5. Subfloor Attachment

• Glue & nail/screw (per APA/IBC). Prevents squeaks from flange shrinkage.
• Use ¾" T&G rated sheathing (24" OC span rating min).

6. Engineering

• Follow supplied layout plan. TJI spacing/depth ≠ sawn lumber spans. Do not "eyeball" substitutions.

*Read the manufacturer’s Installation Guide (Weyerhaeuser, Boise, LP, etc.) before starting. It is the code (IRC R502.1.4).*