Date: September 1993

Rising lumber costs and labor rates, along with the competitive struggle to provide higher quality and more efficient building packages, have stimulated development of alternative framing systems for residential and light commercial construction. At the present time softwoods are the predominant species used in structural framing systems. This situation may change, however, as lumber prices increase, softwood lumber supplies decline and as hardwood species continue to dominate the northeastern region.

The objectives of this research were: 1) to identify alternative structural building components using northeastern hardwoods; 2) to document a case study leading to the development of a design manual for structural insulated panels as an alternative to stick frame construction; and 3) to define the state-of-the-art of the development of structural insulated panel systems as an alternative structural system for houses.

A review of the literature has shown that northeastern hardwoods (yellow poplar, red maple, and red oak) are nailable and treatable and have allowable design values comparable to the commonly used softwoods. The research has also shown that structural insulated panels are emerging as an alternative structural framing system but that there is much work to be completed in documenting their structural performance.

Designers, architects and engineers should be aware of the fact, after reading this report, that they can now apply allowable design values when specifying hardwood materials in solid sawn, glulam, LVL, diaphragm, nail-laminated structural framing systems.

The second year of this research project will focus on the lamination processes, building code specifications and physical testing protocol issues with the goal of establishing criteria for the structural evaluation of a panel configuration under a critical loading condition such as creep and/or combined loading. This evaluation will then be used to develop predictive models for panel structural performance.