Performance. This is what matters.  

Dimensionally stable with a compressive strength of 52 psi, ThermalBuck™ prevents the compression of rigid insulation. The unique “L” shape is designed to transfer both wind & shear loads to the structure itself. Unlike a traditional wood buck, ThermalBuck™ will not warp or shrink over time, and helps to maintain the integrity of the window installation. 


ThermalBuck™ insulates the mounting points of windows & doors with an R-value of 4.4 per inch, lowering the U-value of the wall assembly. It prevents condensation by limiting the thermal bridge in the building envelope. Both the waterproof coating and Dow-Corning 758 sealant help to create an additional air & water barrier in the building envelope.

Technical Downloads

Testing Reports

The testing environment for ThermalBuck™ simulated a 600 lb. window, and ThermalBuck™ was installed with only the Dow Corning 758 Sealant, and nails. ThermalBuck™ didn’t fail. The wall failed. ThermalBuck™ outperformed the wall structure itself.

To qualify as a flashing agent, we recommend installation of ThermalBuck™ with Dow Corning 758 Sealant, then fasten into the framed wall with 2″ nails or screws every 10″ – 12″.  


What is ThermalBuck™ made of?

ThermalBuck™ is made up of a type XIV EPS coated in a polyurethane/polyurea blend resin. It is 100% solids, and does not contain vinyl or phthalates. ThermalBuck™ does not emit VOC’s.

These two elements combined have a compressive strength of 52 psi. Extremely lightweight, strong & durable, ThermalBuck™ is easy to handle, and withstand loads of 70 lbs. per linear inch.

ThermalBuck™ not only meets the definition of a ROESE, but exceeds it.  

ThermalBuck™ Outperforms Wood Bucks 2:1 – Thermal Transfer Testing

Improving the energy-efficiency of new and existing construction has long been a focus of building science. When it comes to insulation, exterior rigid foam is the choice of many builders, because it stops the thermal bridge through the studs.

As effective as rigid foam is as a continuous insulation solution, it presents its own unique challenges with installing windows and flashing the rough openings. Until ThermalBuck™ launched in 2015, there really wasn’t a good way to insulate and create a thermal break around the mounting points of windows & doors.

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Installation Challenge: ThermalBuck™ vs. Wood Buck

    There is no question that ThermalBuck™ outperforms a wood window buck, insulating the mounting points of windows & doors, and acting as a flashing agent. But what’s it going to cost?  We figured no one would believe that using ThermalBuck™ would actually save time and money on the… Read more