Writing by Peter White
Structural insulated panels (SIPs) are not a new building system.
In the 1930s and 1940s well known American architect, Frank Lloyd Wright, used some of the earliest examples of sandwich-panel technology in the Usonian houses.
In these innovative structures Wright endeavoured to incorporate beauty and simplicity into relatively low cost houses. Some of the walls were built using three layers of plywood as structural elements together with two layers of tar paper but lacked any insulation and were never produced on a large scale. There were about 60 Usonian houses built; typically small, single storey dwellings without a garage or much storage.
The concept of a structural insulated panel began in 1935 at the Forest Products Laboratory in Wisconsin, USA looking for products from the abundant forests of North America. Forest Products Laboratory engineers speculated that plywood and hardboard sheathing could take a portion of the structural load in wall applications. Their prototype structural insulated panels were constructed using timber framing within the panel combined with structural sheathing and insulation. The panels were used to build test homes which were continually monitored for over thirty years, then disassembled and re-examined. During this time FPL engineers continued to experiment with new designs and materials.
Alden B. Dow , an architectural student of Frank Lloyd Wright and son of the founder of the Dow Chemical Company, continued to experiment with Wright’s panel design concept. Dow was concerned by the lack of insulation in the Usonian houses and created the first foam core SIP in 1952. Alden B. Dow is generally credited with producing the first structural insulation panels.
By the 1960s rigid foam insulated products became readily available, resulting in the production of structural insulated panels as we know them today.
In the 1990s SIPs saw the development of advanced computer added manufacturing (CAM) technology. Using these systems, computer aided drawings (CAD) can be converted to provide automated cutting machines to fabricate SIPs to the specific design of a building. CAD to CAM has streamlined the manufacturing process bringing further savings to home builders.
Today, SIPs offer a high tech solution for residential and low rise non-residential buildings. Advances in computer aided design and manufacturing allow SIPs to be produced to a high degree of accuracy to deliver flat, straight and true walls and roofs with a structural skin predominately of oriented strand board (OSB). SIPs are available in 5 thicknesses ranging from 115mm to 315mm depending on design requirements.
The design capabilities, exception strength and energy saving insulation make SIPs a twenty first century building material for high performance buildings.
Builders Guide to Structural Insulated Panels (SIPs) Joseph Lstiburek
Building with Structural Insulated Panels. Michael Morley
Prefab Architecture. Ryan E. Smith
Structural Insulated Panel Association