I-joist

The advantage of I-joists is they are less likely to bow, crown, twist, cup, check, or split as would a piece of dimensional lumber.

The disadvantage of I-joists is very rapid structural failure when directly exposed to fire (much like trusses), reducing the time available for residents to escape and increasing the danger to firefighters.

The web is typically made from plywood, laminated veneer lumber, or oriented strand board.

After assembly, the I-joist is end-trimmed and heat-cured or left at room temperature to reach approximately equilibrium moisture content.

The most common mistake is misplacing or improperly sizing holes in the web, which can compromise the joist's strength, potentially leading to structural failure.

[6] In order to use i-joists in a fire-rated assembly, additional detailing is required to ensure building safety.