I-joist

I-joists
An I-joist
A partially constructed floor built with I-joists

An engineered wood joist, more commonly known as an I-joist, is a product designed to eliminate problems that occur with conventional wood joists. Invented in 1969, the I-joist is an engineered wood product that has great strength in relation to its size and weight. The biggest notable difference from dimensional lumber is that the I-joist carries heavy loads with less lumber than a dimensional solid wood joist.[1] As of 2005, approximately 50% of all wood light framed floors used I-joists.[2][clarification needed] I-joists were designed to help eliminate typical problems that come with using solid lumber as joists.

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. I-joists' dimensional soundness and little or no shrinkage help eliminate squeaky floors.

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.

  1. ^ Vogt, Floyd. Carpentry. 4th ed. Clifton Park, NY: Thompson Delmar Learning, 2001
  2. ^ Allen, Edward, and Joseph Iano. Fundamentals of Building Construction. Vol. 4th. Hoboken, NJ: John Wiley & Sons Inc, 2004