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Performance. This is what matters.  


While ThermalBuck is easier to install and flash than a wood buck, it’s the performance that interests most architects and builders. ThermalBuck is made of a type XIV EPS with a density of 3 pcf, and coated in a waterproof resin. It’s lightweight and flexible, yet surprisingly strong and durable.

ThermalBuck handles loads of 70 lbs. per linear inch, and has a compressive strength of 52 psi. ThermalBuck supports the weight of heavy, triple-pane insulated frame windows, and prevents compression of the exterior 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. It prevents condensation by limiting thermal bridging in the building envelope. Both the waterproof coating and Dow-Corning 758 or DAP Dynaflex 800 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 Silicone Sealant, or DAP Dynaflex 800 Premium Polymer Sealant, then fasten into the framed wall with 2″ nails or screws every 10″ – 12″.




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Installation Challenge: ThermalBuck vs. Wood Buck

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