The timber resource in the United States has changed in many ways during the last 50 years and continues to change. Much of the old-growth timber on public and private lands has been harvested, and harvesting on public lands has been greatly curtailed. with harvest levels in the West being well below one-third that of a decade ago. Available timber is now smaller in diameter and lower in quality than ever before. Many species that were deemed undesirable in the past are now being called upon to augment the reduced supplies of more desirable species. Despite these changes in the timber resource, demand for timber from the Nation's forests has increased. In 1996, an estimated 468 ˇÁ 10 6m3of roundwood were required to produce the wood and fiber products consumed in the United States (1). This is the highest consumption level reached so far in the 1990s and is just under the all time high of 488 ˇÁ 106m set in 1987 (1). Because of the high levels of demand and reduced timber supplies, the cost of timber has increased rapidly (2). One response todecreasing supplies of high quality timber, increasing demands for wood and fiber products, and rising timber costs has been a shift from solid sawn to EWP. EWP are designed to replace solid sawn products or other EWP, are more efficient for using the available timber resource, and are cost effective. In this article. the size, species and changes in timber currently being used to produce softwood plywood. oriented strandboard (OSB), laminated veneer lumber (LVL), glued-laminated lumber (glulam), and wood I-joists are examined.

• OSB - Oriented strandboard : OSB is one engineered wood product
• wood, lumber, timber : engineered wood product
• wood: engineered products : woop panels

1. Building codes obstacle or opportunity?
2. Review of wood-based panel sector in United States and Canada
3. Wood products used in new nonresidential building construction