Window installation with exterior insulation is a challenge. Solve the problem with ThermalBuck.

How it Works

ThermalBuck extends the mounting point for windows & doors, and insulates the rough opening to limit thermal bridging. 

Product Sizes 

ThermalBuck outperforms a traditional wood buck, and protects the integrity of your window installation. 

Testing & Technical

PHIUS Verified Psi-Install Data:
Alpen 925 Zenith Nail Fin Installation
with ThermalBuck.

Thermal Bridge Coefficients

News & Events

You Could Win the Most Energy Efficient House in VT! March 26, 2018

Ready for a major life change? Then this contest is definitely worth a look. Green Mountain Power is giving away the most energy-efficient house in Vermont. Sharpen up your keyboard, and submit a 500 word essay detailing why you want to live in the Rutland Innovation House, and how you would contribute… Read more

It’s time for JLC LIVE – Get Your Free Pass February 28, 2018

ThermalBuck is headed to JLC Live 2018 on March 23rd & 24th at the Rhode Island Convention Center, in downtown Providence. And we’d like you to be there. JLC Live New England is widely known as the best hands-on construction show in the business. Focused on live product demonstrations and popular… Read more

If a window isn’t installed properly, it won’t matter how energy efficient it is.

High performance wall assemblies are becoming more common as builders work to make homes more energy-efficient, and meet energy code requirements. But builders know attaching windows with rigid foam or mineral wool isn’t easy. Traditionally a wood buck is built to extend the mounting point, but wood can rot, warp, and shrink over time. It’s not easy to flash wood bucks, and be confident that you’ve got a good air & water seal to prevent moisture intrusion. Wood is a poor insulator, and allows thermal bridging around the rough openings, reducing the impact of the exterior insulation.  


ThermalBuck solves the challenge of installing nail flange windows & doors with exterior insulation by extending the mounting point to create a flush plane for cladding. It also insulates the rough opening, limiting thermal bridging around windows & doors. Coated with a waterproof resin and secured to the rough opening with an air & water barrier sealant* and nails, it’s simple to install and easier to flash than a wood buck. ThermalBuck outperforms a traditional wood buck, and protects the integrity of your window & door installation.


The continuous insulation solution for the high-performance building envelope.

*We recommend ThermalBuck installation with DAP Dynaflex 800 Modified Polymer Sealant or Dow Corning 758 Silicone Sealant 

ThermalBuck in Three Minutes

Watch this quick overview to show you how simple the ThermalBuck installation really is. It takes you through the basic steps from the Simple Installation Guide to install ThermalBuck. You’ll see how easy it is to get ThermalBuck installation right, window after window.

For more detailed versions of each step, watch the complete Step-by-Step Installation Series, including tips on cutting and how to integrate the WRB here.