Trus Joist Corporation (TJ) invented the wood I-joist industry. "The year was 1969. Apollo 11 lands on the moon and Trus Joist Corporation makes the first wood I-beam." TJ not only pioneered the development of this industry, but has maintained a clear leadership role in a hotly contested market. Stiff competition and rapid technological advancement has been good for builders. At one time there was one product and one price --- TJ's. Builders now have a list of brands, prices, service levels, and product lines to choose from.

Cost and performance drove the development of wood I-joists. Contemporary designs, first made popular in the 1970's, were inspired by homeowners who wanted open floorplans. Open layouts require long clearspans. You could buy lumber joists that were longer than 20-feet, but they were expensive, hard to find, and lacked the adequate load-carrying ability required for long spans. Enter I-joists: products made with deep plywood webs edged by strong lumber flanges. Designers now had a free hand to fashion less restrictive load-bearing strategies. Early versions of I-joists were not cheap. But they were straight, lightweight and did the job without breaking a sweat. More recently, the "timber crisis" of the 1990's has made prices of engineered wood more stable than lumber. This is a very attractive feature for builders quoting bids.

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• wood: engineered products : history of I-joist

1. Choosing between oriented strandboard and plywood
2. Common failures in wood structures
3. Decision making in the purchase of siding: a survey of architects, contractors, and homeowners in the U.S. Northeast
4. Decoding building codes
5. Details that keep walls watertight
6. Housewraps, felt paper and weather penetration barriers