Healthy Indoor Air with Mass Timber: Consider Your Adhesives

Photography Copywrite: Stephane Groleau

The decision to use mass timber reflects consumer demand for wood’s aesthetic: calm, organic, warm, well-being, and health-conscious luxury. It is also a reflection of market demand for its sustainability, ecological and human health benefits. Architects talk about “healthy interiors” when advocating beautiful wooden building designs.

So, health and safety are a high priority for both consumers and developers alike. It is not just the safety of the structures; it is emissions too. Safety includes interior air quality and indoor emissions.

There are invisible carbon-containing organic chemicals naturally present in indoor air. They come from many sources, such as flooring, furniture, fabric, and paints. Even trees, humans, and pets emit volatile organic compounds (VOC).

Developers are painstaking in choosing low-emission flooring, paint, and other building products. As a result, VOCs are not typically present at a considerable concentration in the air of today’s buildings to be harmful or to cause sensory irritation symptoms in occupants.

Regulations, naturally, also play a role in decisions about building products that affect health and wellbeing. However, there is no global regulation approach on indoor air concentrations of VOCs emitted by adhesive formulations, specifically formaldehyde concentrations. Multiples regulations were developed over the past decades at different scales, but none have been largely adopted nor have covered multiple engineered wood products. Until 2017 when the US Environmental Protection Agency (EPA) has issued the Formaldehyde Emission Standards for Composite Wood Products, based on the California Air Resources Board’s (CARB), covering the whole US territory. In comparison, the European Standard EN 13986 for E1 classification only covers wood-based panels and is mandatory required in 8 countries out of total 27, and no other regulation is widely applied.

Until a common regulation emerges, there are certifications that the industry can comply with, such as Greenguard (USA), Natureplus & M1 (Europe), JAIA F**** (Japan), which have clearly defined the limits in their programs.

Evolution of Adhesive Formulations

Adhesives have evolved from legacy resins, to synthetic resins that emit low concentrations of formaldehyde, and synthetic polymers that have zero added formaldehyde, and zero adhesive emissions in finished wood products.

To quickly get an idea of the range of emissions related to adhesives, imagine three mass timber rooms. All three are made with wood elements. All wood elements are bonded with approved structural adhesives. But their emission readings are not at all the same. One has a high level of adhesive-related formaldehyde concentration compared to the other examples, at 50 ppm. The second room has a lower level of adhesive-related formaldehyde concentration, at 7 ppm, and is passing Greenguard Gold®, but is still above the limits defined by EPA/CARB. The third has no adhesive-related formaldehyde concentration, at 0.001 ppm, complying with the most stringent indoor air quality standards, such as EPA/CARB and JAIA F****.

                                  Indoor Air Concentrations and Adhesive-
                                   Related Formaldehyde Emissions
Type of Adhesive ppm Comments
Loctite Engineered Wood Adhesives (HB S, HB X, GT20) 0.001 An adhesive with zero formaldehyde emissions, lower than a fir tree complying with the most stringent JAIA F**** and EPA/CARB
Ultra-Low Formaldehyde Adhesives 7.0 Emissions are still above the limit according to EPA/CARB
Conventional Formaldehyde Resin Adhesives 50.0 Greenguard Certified®
Source: VOC ‘s, adhesives and impacts on occupants, Presentation by Chris Whelan at Mass Timber Conference and internal research, March 2021


Formaldehyde is, of course, only a concern when human exposure to it is at elevated levels, but why use it all in mass timber adhesives when there are alternatives with zero potential for added emissions?

Mass timber is gaining ground. It is a renewable building material, outperforming legacy materials on key indicators, such as CO2 and life cycle impact. For many homeowners and investors, it is the most sustainable, environmentally conscious choice. For others, it is most desirable for aesthetic reasons. But all have in common a desire for healthy indoor living.

Developers and the mass timber industry as a whole can go beyond the regulations to not only meet but exceed the expectations of health-conscious consumers and investors by choosing mass timber bonding with zero or ultra-low adhesive emissions.


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