The Energy-Efficient Window Installation
Window installation with exterior insulation is a challenge. ThermalBuck solves the problems presented by “outsulation” by extending the mounting point for windows & doors to create a flush plane for cladding, and allows for structural attachment of the window. It insulates the mounting points with an R-value of 4.4 – 17.6, and acts as an air & water barrier, preventing moisture around windows and doors.
Dimensionally stable, ThermalBuck won’t warp, shrink, or expand like a wooden buck. It prevents compression of rigid insulation, and helps to maintain the integrity of the window installation. Simple to install and easier to flash than a wood buck, ThermalBuck high-performance ROESE saves both time and money – and limits thermal transfer 2:1 over wood bucks.
Simple Installation Guide
Detailed Installation: WRB Interior to Continuous Insulation
These images provide a brief overview of the steps of the most common ThermalBuck installation, which places the WRB against the sheathing and the continuous insulation (or rainscreen) as the final layer of the wall assembly. Download the complete photo guide to show every step along the way, and how to integrate the WRB with ThermalBuck for a high-performance building envelope.
When installing the WRB interior to the CI, first install the WRB, then tape back the head flap and jambs. Cut the WRB flush with RO at sill, and seal the WRB to sheathing at sill. This is the only place where the WRB will go between the ThermalBuck and the sheathing. Next, install ThermalBuck, then let cure for 24 hours. Install the window according to the manufacturer’s instructions. Seal the transition of ThermalBuck to the sheathing at the jambs and head with DAP Dynaflex 800 or Dow Corning 758, then press WRB into the wet sealant. To complete flashing, tape across the jambs and head of WRB across nail flange of window. Install continuous insulation according to manufacturer’s instructions.
Note: consider WRB manufacturer’s recommendation for flashing tape. Download the full set of installation instructions with detailed photo steps.
Detailed Installation: WRB Exterior to Continuous Insulation
These images provide a brief overview of the steps – which start with the Simple ThermalBuck Installation Guide. The continuous insulation is next, followed by the WRB. Download the complete photo guide to show every step along the way, and how to integrate the WRB with ThermalBuck for a high-performance building envelope.
When installing the WRB exterior to the exterior insulation, ThermalBuck is installed first using DAP Dynaflex 800 or Dow Corning 758 Sealant & nailed into the structure. (Note: sealant must cure for 24 hours before the window can be installed.) The exterior insulation is next, followed by the beginning of the WRB installation. Until the window is installed, the WRB can be completed only at the sill. Once the window installation is complete, then the head and jamb flaps of the WRB may be trimmed, sealed, and taped. Complete the flashing with tape across the nail flange of each jamb, and head flap of the WRB.
NOTE: Consider the WRB manufacturer’s recommendations for flashing tape. Download the full set of installation instructions with detailed photo steps.
Preparing the Rough Opening
The most critical point to remember when planning your ThermalBuck installation, is to oversize the rough opening on all 4 sides to accommodate the 1/2″ tongue of ThermalBuck.
The unique “L” shape is an important design element that helps handle the compressive and shear loads, and support the weight of the window.
Review the rough opening preparation from the window manufacturer, then add an additional 1″ overall to their rough opening recommendation to accommodate ThermalBuck.
|Window Width||Rough Opening Width
per Window Manufacturer
|NEW Rough Opening Width
with ThermalBuck Installation
|Window Height||Rough Opening Height
per Window Manufacturer
|NEW Rough Opening Height
with ThermalBuck Installation
Choosing a Sealant
The right sealant is essential in achieving a good air & water seal with ThermalBuck.
You’ll use three 3/8″ beads on every piece of ThermalBuck, on the mitered ends, and around the perimeter where it meets the sheathing. Also, on the nail flange of the window. In the interior, sealant is needed at the transition of ThermalBuck to the window, and where ThermalBuck meets the framing.
We recommend installing ThermalBuck with sealants specifically designed for window flashing and fenestration materials. They’re durable, flexible, UV resistant, and adhere without priming.
To estimate how much sealant you’ll need to install ThermalBuck (including the window), we recommend planning 1.75 oz of sealant per linear foot of ThermalBuck.
Dow Corning 758 Silicone Sealant
This is a commercial grade sealant, packaged in sausage tubes to minimize waste. It requires a sausage sealant gun for use. For more information, please visit dow.com.
DAP Dynaflex 800 Premium Polymer Sealant
This is a residential grade sealant. Packaged in traditional sealant tubes, it requires a standard sealant gun for use. For more information, please visit dapspecline.com.
- Available at Home Depot & other retail locations across the U.S. Check with your local building materials supplier.
ThermalBuck is installed not only with sealant, but secured through the 1/2″ tongue into the structure with 2″ galvanized roofing nails, in order to exceed the minimum 1-1/4″ structural penetration requirement
Use nail gun, or hand nail.
Screws are recommended for installing the window. They must penetrate into the structure a minimum of 1-1/4″. #10 diameter are preferred.
If you’re using a thicker depth of ThermalBuck, and want to use a low profile screw, you might need to order ahead. Helpful links:
Integrating the WRB & Continuous Insulation
ThermalBuck easily integrates with different wall assembly components, and each type of continuous insulation: Mineral Wool, EPS, XPS, and Polyiso. Take into consideration each of the product manufacturers’ installation instructions, and use best building practices for an air & water tight assembly. Here are just a few examples of the most common wall assemblies, and detailed installation instructions of how to integrate the WRB.
Watch our Installation Videos for “on-site” help with each installation step