The I–Joist
The I-Joist is an engineered wood product that comes in multiple lengths and heights. It has advantages over 2x boards, but is more costly.Â
Because I-Joists are manufactured, not sawed from a raw tree trunk, they are never warped or crowned.
Relative to weight, they have greater load-bearing capacity than a 2x.
In some cases, it is possible to use fewer of them, offsetting the higher per cost per unit.
The top section of the I-Joist can be 2 ½ to 3 ½ inches wide, providing a superior nailing and gluing surface.
This makes floor squeaks far less likely to occur.
Some I-Joists feature pre-cut openings to accommodate plumbing, wiring, and duct work.
Your lumber representative will have span tables which indicate requirements of joist size and spacing. A cost comparison versus 2x boards is then easy to figure.
 Â