Floor framing guide

TJI, LVL or Open-Web Floor Trusses?

These products do different jobs. A useful floor-framing decision considers span, load, depth, vibration, openings and the mechanical routes that must fit inside the structure.

I-joists (often called TJI)

Engineered wood I-joists provide consistent depth, straightness and predictable capacity across residential floor systems. They are light to handle and arrive with manufacturer rules for holes, blocking, rim details and bearing. The main coordination risk is treating the web as if it can be cut anywhere. Hole size and location must follow the selected product literature and the project design.

LVL and other engineered beams

Laminated veneer lumber is commonly used where concentrated loads or larger openings require a beam or header. It may support I-joists, conventional joists or trusses; it is not an interchangeable substitute for them. Beam width, depth, plies, fastening, bearing posts and the load path below all matter. Plumbing or duct openings through a beam require specific approval—never an improvised site cut.

Open-web floor trusses

Open-web trusses create generous service routes for ducts, pipes and wiring. They can reduce drilling and make trade coordination cleaner, especially where a dense mechanical layout is expected. The tradeoff is that truss depth, bearing, bracing and openings are established by the supplier’s engineered layout. Late changes can be difficult, so the mechanical design should be coordinated before release.

Comfort is more than allowable span

A floor can satisfy structural capacity and still feel lively. Joist or truss spacing, depth, span, subfloor thickness, fastening and partitions all affect vibration. Discuss performance expectations early, particularly for long open rooms, tile finishes or spaces where occupants may notice movement.

Coordinate before ordering

• Confirm all point loads, stairs, openings and bearing lines.
• Overlay plumbing, heating and ventilation routes.
• Resolve floor depth at stairs, doors and exterior transitions.
• Confirm hangers, rim boards, squash blocks and temporary bracing.
• Use the supplier layout and project drawings at installation.

No single system is automatically best. The efficient choice is the one that meets the design while allowing every trade to complete its work without unapproved alterations.