People often look at ThermalBuck and ask, “How did you come up with this idea?”
Like any good idea, it starts with figuring out you’ve got a problem in the first place. And that’s exactly how this whole process began. John Brooks, developer of ThermalBuck, built his family an extremely energy-efficient, well-insulated house. And he was surprised with how frustrating and difficult it was to install the windows.
So you’ve added exterior insulation to a building, and the depth of the insulation extends past the rough opening, where the windows are installed. The question of “What do we do about the windows?” becomes an important consideration – and a real challenge to overcome.
Rough openings have always presented concerns for air & water sealing on any building, and changing the mounting point for the windows makes them even more vulnerable to moisture damage.
High-performance architects and builders have used exterior insulation for years, recognizing the importance of eliminating thermal bridges in the building envelope. Traditionally, most U.S. builders have insulated between the studs, if they decided to use insulation at all.
But the building practices of the past are giving way to innovation.
“If you see a failure on a building, you can pretty much bet that it started with water.”
John Brooks, president, BRINC Building Products, developer of ThermalBuck
More states are adopting IECC energy codes that require continuous insulation, and builders are striving to understand how building science impacts the energy efficiency and quality of their work. Use of exterior insulation in both new construction and renovations is growing significantly, so solving this challenge has become a priority.
Mounting Windows Directly Over Foam
Often builders choose to mount windows and doors right over the exterior insulation, particularly for depths in the .5″ and 1.0″ range. But the nail flange compresses the insulation, creating gaps for air and water to enter. There is also a lack of good support for wide, heavy windows, which can affect the long-term operation of the window. Martin Holliday of Green Building Advisor spoke with Cordell Burton, an installation engineer at Pella Windows, about the issue in 2011.
“You can’t screw through foam sheathing – the foam will compress. You have to have something solid to attach the window to.”
Cordell Burton, Pella, as quoted in Musings of an Energy Nerd, Green Building Advisor, May 2011
For insulation depths over 1.5″, builders generally built “wood bucks”, made of plywood or dimensional lumber, to extend the mounting point of the window.
The Traditional Wood Buck
While wood solves the problem of extending the mounting point, it creates some new problems of its own in that it often will warp, rot, and shrink.
Wood is a poor insulator, so wood bucks allow air to transfer around each window and door through the rough opening. Cold air is denser than warm air, so in the winter the heated indoor air heads outside, and in the summer, the hot, humid air outdoors moves into the cool air-conditioned interior. This transfer of energy is called thermal bridging, which is what continuous insulation is designed to eliminate in the first place.
The Problem with Thermal Bridging
Thermal bridging isn’t just about wasted energy – although a home that’s more expensive to heat and cool and isn’t comfortable is a legitimate problem. But it’s really about water. Builders know if bulk water isn’t managed properly, it can cause extensive damage to a building. But the moisture that forms from condensation also causes issues over time.
“Another hidden concern is condensation, which can be a consequence of thermal bridging. When warm air comes into contact with a cold spot on the floor or wall, water vapor in the air cools and collects as droplets on the colder surface. This can result in durability problems, as well as poor indoor air quality,” said Joanna Grab, Senior Sustainability Consultant, Steven Winter Associates.
The more we insulate our buildings, the more important it becomes to reduce the potential for condensation to form – good building sense in any climate.
“Another hidden concern is condensation, which can be a consequence of thermal bridging. This can result in durability problems, as well as poor indoor air quality.“
-Joanna Grab, Senior Sustainability Consultant, Steven Winter Associates, as written by Kate Danielsen, High Performance Walls on swinter.com, January 2017
Building a Better Mousetrap: The Process
John Brooks was very familiar with the problems associated with wood bucks. After losing his home in a fire, John built a new home for his family with his own hands. They settled in to make a new start, only to watch as condensation and mold formed around the new windows. Not only did the wood bucks he built cause condensation issues, the flashing process was so difficult that the whole installation process amounted to an exercise in frustration. He began to think there had to be a better way to install windows.
Using his background in construction and his experience in the insulation industry, John began to make prototypes for a product that would be better than a wood buck. It needed to solve multiple problems and still be cost-effective. Here’s the wishlist John had for his new product:
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- Extend the mounting point
- Prevent the compression of exterior insulation
- Insulate the rough opening
- Protect the rough opening from moisture damage
- Support the window
- Handle shear & wind loads
- Provide durability, strength & flexibility
- Install easily
- Simplify flashing & integrate with the WRB
- Maintain the long-term operation of the window.
Anyone who has ever come up with a great idea for a new product will agree that the “eureka” moment doesn’t happen without a long period of not-so-great ideas, that take you back to the drawing board time and time again, testing both your patience – and your determination.
This was no different for John, who spent all of his spare time and most of his money on this project, often struggling not to give up. A chance meeting with some strangers at a restaurant, the desire to build a strong business to help sustain their community, and shared Christian beliefs poured new life into his research. After 4 years of prototypes, trial & error, third-party testing, and an unwavering personal faith, John realized his vision for ThermalBuck as it exists today.
The Innovation: ThermalBuck
ThermalBuck is an L-shaped window buck that goes inside the rough opening, and extends outward to create a flush plane with exterior insulation and/or rainscreens.
ThermalBuck is made of a type XIV high-density EPS, and coated in a waterproof resin. Not only does it have the compressive and shear strength to handle the weight of large, high-performance windows, but it also insulates the rough opening with an R-value of 4.4 per inch to limit thermal bridging around the rough opening.
The High-Performance Future of Building
In 2016, Scott Gibson of Green Building Advisor presented ThermalBuck as “An Alternative to Wood Bucks”, and the building industry took notice.ThermalBuck began to receive widespread media recognition, and garnered a lot of attention at conferences and trade shows, because there was nothing like it – it’s simple to use, and solves a common problem.
“This is an impressive product. Once you see it, you really understand the problem this solves for builders like me.”
-Matt Risinger, Risinger Construction, The Build Show
John met Matt Risinger at the EEBA conference in Dallas, Texas, in 2016. Based in Austin but originally a Pittsburgh native, Matt had a western Pennsylvania connection with John.
Matt is a highly respected builder, educator, and self-proclaimed “building science geek” with over 300,000 followers on his popular YouTube channel, Build with Matt Risinger.
He’s well known for sharing solutions and new products to his thousands of followers – and appreciated for his candor. Risinger took home our tabletop displays to share with his building community and gave ThermalBuck great feedback. John was fortunate to film some videos with Risinger & Co. in Austin, and the building community took notice.
The rest, as they say, is building history.
Follow ThermalBuck’s path in the media here.
Want to learn more? We recommend these excellent building science resources: Heat Rises… and Falls – Stack Effect, Air Movement and Heat Flow, Allison Bales, Energy Vanguard. How it Works: Vapor Drive, Rob Yagid, Fine Homebuilding. Plan Ahead to Save Energy – Martin Holladay, Fine Homebuilding.
ThermalBuck and Alpen are an ideal fit for architects and builders looking for the optimal way to install high performance nail flange windows with continuous insulation.
For information regarding ThermalBuck distribution rights and purchasing in Canada, contact the high-performance team at 
A Passion for Sustainability
The Alpen HPP Zenith Series ZR-9/ 925 window features up to R-9.1 insulation, 99.5% UV protection, insulated frames, and Alpen Glass, Alpen’s renowned Suspended Film Technology. Every Alpen window has 9 key design features that make these highly engineered windows some of the best in the industry. Read more about the technology and craftsmanship of Alpen windows 
