Nature Does it Best: Gutex Wood Fiberboard Insulation

Nature Does it Best: Gutex Wood Fiberboard Insulation

Gutex, based in the Black Forest of Germany, has produced insulation from wood for over 85 years. Today, Gutex is a leader in innovative, environmentally-friendly manufacturing. Gutex uses a mixture of post-industrial, recycled wood chips and shavings and milled wood that has been harvested and grown using sustainable forestry management practices.

Why Wood?

Wood fiber insulation is a safe, natural, and high performing alternative to many synthetic insulation options currently on the market. Wood is a renewable resource and a natural carbon sink. There are many different varieties and uses for Gutex products, but the general recipe for a Gutex board is 95% spruce/fir wood, 1% paraffin, and 4% PU resin – making it a carbon negative material made from renewable resources that is a great alternative to mineral wool and foam insulation.

As Gutex says, “nature knows best”, wood has natural vapour open and thermal retention properties that make it the ideal insulation material.

Varieties of Gutex Insulation

Multitherm and Ultratherm are the most accessible varieties of Gutex available. All other products seen below require custom ordering and delivery. Reach out to 475 to quote your project and find out more.
Moisture-resistant wood fiberboard insulation and weather resistive barrier in one, for exterior walls under rain screens. High R-value rigid insulation board and roof underlayment in one, made from moisture resistant wood fibers. High quality single-ply construction. Wood fiber batt, produced from all renewable resource wood fiber. Homogenous fiber structure make this the best friction-fitting batts in North America.
Highly compression-resistant wood fiberboard insulation for floors, walls, ceilings and roofs. Use exterior when protected by Pro Clima WRB. Rigid insulation board and roof underlayment in one, made from moisture resistant wood fibers. High quality single-ply construction. Loose wood fibers for blown-in installation – both dense and loose fill. For walls, ceilings and roofs.

Continuous Insulation + Weather Resistant Barrier

The biggest benefit of using Gutex’s ULTRATHERM and MULTITHERM boards is that you can insulate and weather-proof your assembly in one simple step, cutting labor costs in half. These boards are applied at the exterior, and tongue and groove edges make installation very fast. Because you do not need to line the vertical edges of the boards up with the studs/joists below, you minimize cutting, reduce waste and maximize application speed.

“By adding this board on the exterior, the building is clad, weather and wind protected in one step”

This assembly is watertight thanks to two properties of these boards. The ULTRATHERM and MULTITHERM boards achieve moisture resistance through a hydrophobic treatment of 0.5% paraffin. The tongue and groove assembly also ensures that the boards are immediately waterproof and wind-tight. The building is now protected from the elements during the interior construction phase. The final cladding/roofing should be added within three months.

There are a few remaining details such as valleys, outside corners, dormers, chimneys and windows that need to be additionally waterproofed with tape connections. Simply prime these areas with TESCON Primer RP, and use TESCON VANA 150 to make these connections waterproof and windtight.

vapour Open

GUTEX boards are waterproof and vapour open. The paraffin treated boards stop liquid water infiltration, water droplets roll off the boards. The vapour open wood fiber allows the passage of water vapour through the boards, preventing condensation formation in the assembly. Gutex wood fiberboards are very vapour open, with 44 perm/in, to ensure that your walls can dry out if unforeseen humidity or vapour does enter the assembly. They provide a high drying capability to insulated enclosures, something that is not possible with foam boards. These boards can hold up to 15% of their weight in moisture without losing their insulation capacity, then, when the air is dry, the moisture diffuses out of the assembly. By allowing moisture to escape from and pass through the assembly, you create a safer, more resilient wall assembly that is much less susceptible to mold formation.

Superior Thermal Insulation

Wood has a very low thermal conductivity and a high specific heat capacity, resulting in a material that resists temperature fluctuations. This principle applies in both hot and cold conditions, keeping the assembly warm in cold weather and cool in hot weather. The boards can delay internal temperature rise by 10 or more hours (in combination with dense pack insulation), as shown in this test performed by GUTEX. In contrast, low density materials like foam, mineral wool or fiberglass will heat up rapidly and cannot offer this benefit. this test performed by Gutex. In contrast, low density materials like foam, mineral wool or fiberglass will heat up rapidly and cannot offer this benefit.

The time lag- time it takes for heat to reach the interior of the building through the insulation- is 10 hours for Gutex Thermosafe. On a day where the outside temperature fluctuates by 70 degrees, the indoor air temperature only changes by 5.5 degrees.

Sound Insulation

High densities (from 8.75lbs/CF to 12.5lbs/CF) and tight tongue and groove joints give the boards ideal acoustic properties. Wood fiber can effectively dampen not only airborne sounds from traffic or loud music, but also impact sound caused by construction equipment or heavy footsteps. When installed properly, GUTEX boards can reduce sound levels by 50 dB. Wood fiber is a more effective sound barrier than foam, mineral wool or fiberglass because of its higher density and open porosity.

How To Start Using Gutex Now

Transitioning to new materials can be a difficult process when accustomed to a certain way of doing things. We’re here to help with the first two steps to making Gutex a reality in your next project.


First off, understand how Gutex wood fiber insulation will fit in to your design with our Smart Enclosure assembly guidance. The Smart Enclosure is a free downloadable toolkit that can help you maximize the positive impact of your building projects, and relies heavily on the Gutex benefits described above to provide optimized comfort, safety, energy efficiency, and negative carbon emissions.

Second, get the ball rolling by quoting your project. We’re here to help specify which Gutex varieties will work best for your chosen assembly, and help calculate the amount you’ll need to do the job. Whatever stage of the project you’re in, 475 is here to help.