Re-evaluating Evaluation : New Materials, New Methods

In today’s world of energy-efficient building requirements, structural insulated panels (SIPs) remain an attractive option. Modern SIPs combine the strength of wood with the energy-saving attributes of cutting-edge foam plastic insulation, to create a cost-effective solution for construction professionals. These sandwiched panels stand ready to meet the building codes of tomorrow, but many fear that the lack of adequate, systematic testing of these new materials may hinder their popularity and stifle their widespread implementation.

The Forest Products Laboratory (FPL), APA – The Engineered Wood Association, and the Structural Insulated Panel Association are on a mission to change this. Because of their unique construction, researchers believe SIP walls must be tested differently than more common light-frame walls. Unlike traditional walls, SIP walls are required to bear weight on their cap and sill plates, so that vertical loads from the story above are effectively transferred down to the foundation.

Creep test setup for a structural insulated panel.

A structural insulated panel undergoing performance testing at FPL.

This “restrained” method of evaluation yields the most accurate data for SIP performance.

Until recently however, SIP walls have been evaluated in the same way as their conventional light-frame counterparts, using an “unrestrained” configuration. Researchers fear that these tests may not realistically reflect the lateral load-bearing ability of the SIPs.

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A diagram illustrating how the 24 full-size SIPs will be tested.

Between May 2015 and August 2016, 24 full-size SIP walls will undergo a carefully monitored regime of restrained, lateral load performance tests, which represent the most common configurations used by industry professionals. Researchers will consider a wide range of variables — from the obvious, such as wall thickness and type — to the minute, such as nail size and nail spacing. The final report will be prepared by December 2016.

Results of this project will not only increase the accuracy SIP performance data, it may help guide further evaluations of similar building materials in the future. Most importantly, it will provide construction and design professionals with the data they need to make informed choices when considering these new building materials, so that they can keep tomorrow’s buildings efficient and safe.

For more information, please see this Research in Progress.

 

FPL Partner Procures Patent: Better Building With BioSIPS

Whether serving as a bookshelf, tabletop, or wall panel, the composite board is a ubiquitous construction material found in furniture and homes alike. Traditional composite boards use mankind’s most trusted building resource, wood, as a base — but a new patented process using waste products stands to revolutionize the familiar building material, making it even more sustainable and environmentally friendly.

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BioSIPS use low-value recycled material to make high-value structural materials.

Julee Herdt, a professor at the University of Colorado – Denver, and Kellen Schauermann, a former graduate student, were recently awarded a patent for their Bio-Structural Insulated Panels (BioSIPS) system. BioSIPS are structural boards comprised of waste material such as recycled paper, noxious weeds, industrial hemp, and forest debris.

Herdt, the CEO and president of BioSIPS Inc., hopes that her product will help ease the environmental and energy concerns of tomorrow.

Although wood-based Structural Insulated Panels (SIPS) have been around for some time, Herdt’s BioSIPS, made from 100% recycled material, could replace their conventional wood counterparts. BioSIPS wall, floor, and roof panels even surpass conventional SIPS in some strength-testing areas (especially compressive and transverse loading) as well as exhibit superior thermal characteristics — which is important, as thermally-efficient structures go hand-in-hand with decreased energy usage.

Herdt’s accomplishment comes on the heels of a long legacy of research and collaboration with the Forest Products Laboratory (FPL). In 1995, she was part of a project that researched and tested GRIDCORE (FPL’s Spaceboard) panels — three-dimensional, molded structural panels comprised of recycled corrugated containers, old newsprint, and kenaf, a plant native to southern Asia. The name “spaceboard” referred to the spaces afforded by the waffle-like design of the GRIDCORE panels, which allowed for increased strength and decreased weight and material usage.

Nearly 20 years later, BioSIPS, like GRIDCORE panels before them, carry on the tradition of turning society’s low-grade waste into high-value products that have proven utility in real-world construction projects. Along with her personal office, Herdt and her team built entire houses with BioSIPS, winning first prize at the U.S. Department of Energy’s Solar Decathlon in 2002 and 2005.

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Herdt, Schauermann and Hunt await another patent for new methods of creating complex three-dimensional shapes with fiber boards.

Herdt and Schauermann, along with FPL Research General Engineer John Hunt, are awaiting the award of a second patent, Cut-Fold Shape Technology for Engineered Molded Fiber Boards, which relates to a new process of folding fiber boards into three-dimensional shapes to maximize their utility and strength.

In a world of increased environmental awareness, BioSIPS promise to offer designers, engineers, and industry professionals new ways to build strong, energy-efficient structures and provide another avenue for society to make better use of its waste products. Through technologies like these, we will better be able to tackle the construction challenges of tomorrow in an environmentally responsible way.

 

 

Creep Performance of Structural Insulated Panels (SIPs)

Few places in the United States can understand cold like the Midwestern United States. In Wisconsin, where January’s low temperatures average around 13 degrees Fahrenheit and snowfall is typically measured in feet, a well insulated home can spell the difference between enjoying the winter and enduring the winter. At the Forest Products Laboratory (FPL) in Madison, Wisconsin, helping to evaluate effective yet structurally sound insulation methods for wooden construction is a small but important part of the laboratory’s vast repertoire.

Modern construction efforts have incorporated more and more structural insulated panels (SIPs) into designs—and with good reason. SIPs are a panel-shaped building material that consist of two wood-based composite boards with an insulating layer of foam plastic in between them. The end result is extremely strong, energy efficient and cost effective.

Creep test setup for a structural insulated panel.

Creep test setup for a structural insulated panel.

Although SIPS have been used in floor and roof applications for years, little is known about their long-term structural integrity. Recognizing this gap, researchers at FPL set to work investigating the “creep performance” of these systems, or the tendency of the panel to deform when subjected to a sustained load. The rate of creep deformation is a function of material, time, temperature, moisture, and applied load—and the right combination could spell structural failure.

The project, in cooperation with The Engineered Wood Association (APA) and the Structural Insulated Panel Association (SIPA), began in 2013 when 12-inch-wide panels were brought to FPL to be subjected to 90 days of shear and bending tests. The SIPs performed very well, and all of the 24-foot-long sections survived without any bending failure. In addition, after a recovery period, researchers retested the panels to determine the residual strength of each panel. Again, the SIPs remained strong, unfazed by the 90-day test.

Based off the positive results from the first test, the team launched into the next phase of the project. The second phase kicked off in 2014, and was much more comprehensive than 2013’s efforts. This round of tests involved as many as 28 specimens per test configuration, several different configurations, and lasted into spring of this year. Although the research is completed, the final report has yet to be released—but when it is, building professionals will have a new body of knowledge that will allow them to incorporate SIPS into designs with added peace of mind.

When the days get darker and the snow begins to pile up, SIPS have always been trusted to keep the cold air out. Now, consumers will be able to rest assured that bending, shearing and other deformation won’t be creeping in at night either.

Tales from the Test Floor

Structural insulated panels (SIPs) are the latest material being put to the test in FPL’s Engineering Mechanics and Remote Sensing Laboratory. SIPs are high performance building panels used in floors, walls, and roofs for residential and light commercial buildings.sips3

Engineering technician Dwight McDonald installs sensors to collect data during the test. The test will evaluate the mechanical properties of the SIPs.sips1

As the Instron machine applies force, the SIP flexes under the load until reaching its breaking point, literally.sips4Researchers will look at how and where the SIPs failed as part of the evaluation process. Understanding the mechanical properties of SIPs and other high performance building materials supports their efficiency and use in construction by improving design standards and building codes.

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