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Materials & Assemblies

Introduction to GUTEX Thermowall: External Insulation + Finish

September 5, 2017

GUTEX, our favorite wood fiber insulation provider, has a new system available in North America for the first time: GUTEX Thermowall. Thermowall is an external insulation finish system (EIFS) consisting of thick, continuous GUTEX wood fiber insulation board and a 3-layer stucco system. It is highly versatile and can be used over wood, metal and masonry constructions.


Download the Thermowall Install Guide to see the full installation instructions.

The installation steps are simple:

  1. The THERMOWALL fiber insulation boards are installed using thermally broken washers.
  2. A 2-ply layer of undercoat is applied directly to the board with a reinforcing mesh embedded while wet.
  3. This is followed by the 3-layer stucco system consisting of: primer, antifungal paint, and a finish plaster, available in a variety of colors.
  • Beautiful stucco finish on a Thermowall insulated home.


External Insulation
Insulating the exterior of your walls offers several unique advantages over an internal insulation. It decreases the chances of thermal bridging by wrapping the entire building in a thermal envelope. Any existing gaps in your exterior walls, whether they’re wood, metal or masonry construction, will be eliminated with the application of this system. With Thermowall, the energy used to condition living space is absorbed and retained in the high thermal mass of the assembly. GUTEX insulation buffers summer heat more effectively than other exterior board insulation, such as mineral wool and foam. reducing fluctuations in the indoor air temperature. Thermowall is an external insulation finish system, providing insulation and a new exterior finish in one.
Vapor Open
Like GUTEX’s other products (watch this Introduction to GUTEX video to learn more about those), all components of this system are vapor open. The specialized lime/silicone stucco is highly compatible with the insulation board and does not inhibit its vapor open properties; the entire system is rated at 44 perm/in, which allows the wall to dry out if any unforeseen moisture enters the assembly.

Indoor Comfort
Gutex Thermowall has exceptional specific heat capacity (2100 J/kg K) leading to maximum protection against heat in summer and cold in winter. The insulation and continuous weather resistive barrier reduces thermal bridging and making the structure wind tight.

Sound Attenuation
The thick, dense wood fiber insulation boards provide an effective sound barrier, making your home a comfortable, quiet place to be. Here’s a quick video we took on a tour of GUTEX facilities in Germany that demonstrates the point:

Stucco Render
The Thermowall finish render coat is a light dash coat available in various grain depths and colors. Color books are available upon request. GUTEX also supplies a full external insulation accessory system which includes base rails, angle beads, and fasteners.

Request a quote for your project on the GUTEX Thermowall product page.

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