Insulation Guide Hopes to Comfort Engineers and Occupants Alike

If you haven’t been on a construction site lately, the word “insulation” will bring to mind one thing: long rolls of paper-backed pink fiberglass. This decades-old mainstay of residential construction is used in over 90% of homes in the United States, but it is not the only, nor the most efficient, type of insulation.

As the demand for high-efficiency building materials increases, engineers and contractors are looking for new ways of keeping the occupants of tomorrow’s buildings comfortable, and the existing buildings of today compliant with increasingly demanding codes.

One possible solution? High-efficiency foam insulation and wood structural panels. The problem in implementing these new technologies? The unknown.

A computer illustration of a 2x6 wall framing package.

A computer illustration of a 2×6 wall framing package.

Changes in building codes mean that existing buildings looking to improve their R-Value (a measure of an insulation’s efficiency) are left with two options: increase the cavity insulation, or add exterior insulation. Despite its ease of use and high performance, only 10% of homes use exterior rigid foam and insulated wood structural panels. Implementation of these new materials are limited by a lack of specific performance details and concerns over long-term moisture performance and hazard resistance.

The Forest Products Laboratory (FPL) hopes to answer some of these questions, and help bring high R-Value exterior foam and insulated wood structural panels into the mainstream. In cooperation with the Department of Energy’s Building America program and Home Innovation Research Labs, FPL researchers are working to assemble a Builder’s Guide to support a wider adoption of energy-efficient wall systems in residential construction.

The first edition will focus on two primary wall systems: 2×6 walls with optimized framing and 2×4 walls with exterior foam insulation. These two wall systems represent the best of adaptable, mainstream, energy-efficient options that use standard materials and require a minimal learning curve.

The guide, geared toward industry professionals, should be available in early 2016, and will contain advice for builders that can be readily implemented in the field using available methods and materials. The publication will cover everything from minimum code requirements and best practices, to 3-D graphics showing various construction options.

With this new guide, builders and engineers will have peace of mind about the performance of these new technologies and be armed with the knowledge to make informed decisions about these new insulation systems. Together, they will keep us all warmer in the winter, cooler in the summer, and reduce our energy requirements for the decades ahead.

For more information, please see the FPL Research in Progress publication Builder’s Guide to Energy-Efficient and Durable Wood-Frame Walls.

Inside View House Teaches Energy-Efficient Construction Practices

The following is a press release from APA – The Engineered Wood Association:

A new home under construction in suburban Chicago has become a learning tool for builders, architects, and code officials to experience and observe how efficient framing practices can conserve energy, speed construction, and reduce utility bills. The Inside View Project, a demonstration house by Beechen & Dill Homes, provides a hands-on look at straightforward energy-efficient construction techniques that can be easily replicated in nearly any house around the country.

The Inside View Project provides a look at energy-efficient construction techniques. (Photo courtesy of APA.)

The Inside View Project provides a look at energy-efficient construction techniques. (Photo courtesy of APA.)

Co-sponsored by the USDA Forest Service, Forest Products Laboratory and APA – The Engineered Wood Association, the Inside View home features advanced framing practices such as 24-inch on-center spacing and corners and headers that provide more space for cavity insulation. The robust floor system also features 24-inch on-center spacing, allowing for ductwork runs while eliminating about one-third of the required joists and subsequently requiring one-third less labor and adhesive. Higher-series, deeper 14-inch I-joists allowed the builder to avoid double joists and, in combination with an upgraded 7/8-inch OSB subfloor, resulted in a stiff floor system despite the wider spacing.

“We’re always striving to be on the cutting edge. We were the first in the area to build energy-efficient homes and to guarantee energy bills; now it’s industry standard,” said Ed Kubiak, director of construction for Beechen & Dill. “With prices going up and labor harder to find, techniques such as these that reduce energy use while making more efficient use of materials and allowing for more efficient construction are the direction the industry needs to be going.”

Beechen & Dill opened up the Inside View house to building pros during a series of open houses July 28 and 30. Visitors had the opportunity to tour the house under construction, with walls and floors left exposed for easy access to viewing and learning about these framing techniques.

“It’s good to be in a house that’s not dry-walled, yet, to be able to see and learn more about the techniques that they’ve been talking about,” said Karen James, community development director for the Village of Shorewood, who attended with several code officials from the nearby town.

“It was a great idea to do this, especially to this extent,” said architect Bruce Obora of Chicago-based Obora & Associates, noting that his firm has designed one home using some advanced framing techniques but is continuing to research the methods in anticipation of additional projects in the future.

The Inside View home, located at 15328 S. Oak Run Ct. in Lockport, is one of 16 houses in the final phase of Beechen & Dill’s Creekside Estates development. The two-story, 2,880-square-foot house includes four bedrooms and two-and-a-half baths, along with a two-story family room, full basement, and three-car garage. As part of a partnership with the Environments for Living program, all of Beechen & Dill’s homes carry an energy bill guarantee, assuring potential buyers of long-term operational costs.

“Energy-efficient 2×6 framing can reap significant monetary savings for homeowners throughout the life of their home, while also helping the builder save on installation time and save costs in meeting the energy code. It’s a win-win,” said Tom Kositzky, director of field services for APA. “What’s more, these techniques are not difficult to implement or understand; once designers, builders, and code officials get familiar with the practices, they can easily become a regular part of their routine.”

“Education is key to furthering the adoption of energy-efficient building techniques. The Inside View Project gives us an excellent learning lab where Beechen & Dill can share ideas and techniques with other design/build professionals in the Chicago area,” added Mike Ritter, assistant director of the USDA Forest Service, Forest Products Laboratory.

For more details on the project, visit


Fastener Follies: Avoiding the Complications of Corrosion

A creak here, a groan there—the familiar orchestra of an aging deck. Though in most cases these noises are innocent, some may betray a deeper problem. Beneath your feet could be impending disaster, a backyard platform poised to plummet to the ground below—even if the wood comprising it is completely sound.

Corroded metal fasteners have been responsible for several deck collapses across the country, and tragically, decks seldom fail when they are unoccupied. Researchers at the Forest Products Laboratory (FPL), in cooperation with the United States Department of Transportation and the Federal Highway Administration, have been investigating metal fasteners, and their corrosion problems, for years. They found that although wood is generally not corrosive, copper-based wood preservatives can react with the metal components of the deck, and lead to compromised structural integrity.

Corrosion of a galvanized joist hanger and nails supporting a wood deck treated with a copper-containing wood preservative. This deterioration would be easily spotted during a visual inspection.

In 2004, changes in regulations saw an influx of wood treatments with increased copper content. Although effective at preserving the wooden components of external structures, they increase the incidence of corrosion.

When two dissimilar metals (for example, the nails in a deck and the wood’s copper coating) come into contact with one another, the electron exchange between the two materials begins the corrosion process. In addition to producing unsightly rust, this significantly weakens the metal.

Fortunately, there are several steps you can take to mitigate these hazards. Because dry materials do not react with one another, FPL stresses that, “proper moisture management is the most important thing one can do to reduce corrosion of metals in treated wood.” This includes preventing moisture from seeping in through the ends of wooden components (where it moves into the timber up to 10 times faster than from other directions) and designing roofs and overhangs so that they do not drain onto lower structures. Researchers maintain that, “if the wood is kept dry, both the wood and fasteners can last for centuries.”

Illustration of the importance of roof overhangs for protecting wood from biodeterioration and corrosion. The right side of the beam is protected by the large roof overhang, whereas the left side is exposed to rain.

Illustration of the importance of roof overhangs for protecting wood from biodeterioration and corrosion. The right side of the beam is protected by the large roof overhang, whereas the left side is exposed to rain.

Isolating the metals from one another is another step one can take. The most common way of doing this is through non-metallic coatings, such as those found on some screws or bolts designed for exterior use. Extreme care must be taken however when using coated metals in construction, as the coatings can be easily damaged during the installation process.

Finally, avoiding metal-on-metal contact altogether is a surefire method to prevent corrosion, but the hardest to implement. Although copper preservatives and metal nails are sometimes unavoidable neighbors in deck construction, being aware of metallic washers used on dissimilar metal bolts, or metal signs hung by metallic screws, can help put a damper on the corrosion process. Using non-conductive washers with metal signs or joist hangers, for example, can significantly decrease the speed of the corrosion and extend the life of the metal by decades.

Preventing corrosion is a multi-billion dollar industry in the United States, with over $100 billion spent in protective coatings alone. It is a problem as old as the material itself and wherever moisture and metal are found, corrosion is sure to follow. By utilizing proper construction techniques, moisture management, and, of course, regular inspections of your deck or home, your fasteners can last a lifetime—and your deck and family can be spared the tragic results of corroded metal fasteners.

For more information, please see the FPL’s Guide for Materials Selection and Design for Metals Used in Contact with Copper-Treated Wood.

Solid Research on Shaky Science: Building with Wood in Earthquake-Prone Regions

Nepal 2015—Japan 2011—Chile 2010.

In the past decade, these nations, and many others, have been host to some of the most destructive earthquakes in recent memory. Along with the inestimable human and emotional toll these events take on communities around the globe, the costs associated with reconstruction efforts are equally astronomical, often edging into the billions of dollars. Although we can’t effectively predict or stop earthquakes from occurring, we can be ready, and minimize the impacts of these damaging seismic events.

CLT concept and use in a nine-story mid-rise building in London.

CLT concept and use in a nine-story mid-rise building in London.

From relatively stable ground in Madison, Wisconsin, researchers at the Forest Products Laboratory (FPL) are searching for better ways to build more resilient, taller, safer, and cost effective wooden structures for use in earthquake-prone areas of the nation. For the wood building community, the most viable tall building construction solution incorporates the use of cross-laminated timber (CLT).

A CLT panel consists of multiple layers of kiln-dried lumber boards stacked in alternating directions, and bonded together with structural adhesives. The end result is an inexpensive, strong, solid, rectangular panel that can be used for building walls, floors or roofs.

CLT has already established itself as an important building material in Europe, but is relatively new to North America. Wooden buildings over eight stories tall, which incorporate CLT into their design, have sprung up in areas of low seismic activity to include Sweden, Australia, and the United Kingdom. Experts believe that CLT could also be a cost-effective and environmentally friendly alternative to traditional construction materials for buildings up to 125 feet tall.

FPL, along with the Coalition for Advanced Wood Structures, is developing seismic design perimeters for CLT use that will meet or exceed both design and safety codes. The team hopes that the project will lead to the development of a performance-based seismic design (PBSD) methodology to investigate the feasibility of three prototype systems. This PBSD would allow for the construction of buildings in earthquake-prone areas up to 14 stories tall using CLT components.

Researchers believe that this project will lay the ground work for buildings with elongated natural periods, near elastic behavior, and an increased resiliency to the high forces and accelerations of seismic events.

The growing trend of urbanization has increased the need for taller buildings across the country, including in areas that are crisscrossed by tectonic boundaries like California’s San Andreas Fault or the Cascadia Subduction Zone of the Pacific Northwest. At the same time, more emphasis has been placed on environmentally and fiscally responsible construction. Properly rated CLT construction holds great potential for cities like Los Angeles or Seatte—urban areas that have already witnessed tragedy in the past, but hopefully, when and if the next disaster occurs, can be headline-making cities for their successful implementation of safer building techniques.

For more information on, see this Research In Progress report.


Home Wreckers in Search of Moisture: Tips for the Homeowner

The work of FPL’s Durability and Wood Protection Research Unit is broad in scope and includes studies into damage and contamination by decay fungi, mold, and termites. All these household pests are attracted to excess moisture, which can result from inadequate surface drying of condensation, leaks in pipes and foundations, poor ventilation, or flooding.

Homeowners are increasingly concerned about moisture management and indoor air quality. However, chronic moisture problems in a home can lead to more than poor indoor air quality—persistent high moisture can lead to a cascading biological succession from mold to decay to termite damage.


Blue-black color on walls shows evidence of mold growth. (Photo used with permission from A&J Specialty Services, Inc.)


Contamination with mold can render a home unlivable, and cleanup may require gutting the entire structure. In some cases, cleanup costs for toxic molds can equal the value of the home!

  • Mold occurs on the surface of wood exposed to excessive humidity or wet/dry cycling.
  • Visible mold growth is a good indicator of damp conditions or excess moisture.
  • Water vapor in humid air will not wet wood sufficiently to support decay fungi, but it will permit mold growth.
  • Mold, though unsightly, causes insignificant strength loss to structural wood components.
  • Common mold fungi can cause allergic symptoms; however, some molds (Stachybotrys sp.) produce mycotoxins, which cause illness and make homes uninhabitable.
  • New York City Department of Health and the U.S. Environmental Protection Agency have established guidelines for the assessment and remediation of mold fungi in indoor environments.