Flooring Installation Hazard Spectrum

Three primary installation methods for flooring are mechanical, such as  nails or tacks; interlocking tiles and click systems common in floating floors; and adhesive. The chemical content of materials used for flooring installation varies, but in general they can be grouped into several categories, and some of these categories tend to contain less hazardous chemicals than others. Below, HBN ranks different types of flooring installation options on a simplified spectrum.[1] Products in the green categories are typically better options than those in the orange or red, and products in the yellow categories are generally less preferable than those at the top, but are better choices than those at the bottom.

The best way to avoid the hazards associated with flooring installation products is not to use an adhesive. Look for products that can be installed with nails or other mechanical fasteners. Avoiding adhesives can keep hazardous chemicals out of interior spaces, and supports the future recycling of flooring because adhesives make some materials unrecyclable.[2] Interlocking tiles tend to have additional layers which can introduce additional hazards, but are still typically a better option than most adhesives.

As a category, adhesive manufacturers tend to reveal little about what’s inside, making it difficult to ascertain which products have hazards, and what their severity may be. Encourage manufacturers to fully disclose the content and associated health hazards of flooring adhesives through the industry’s collaborative, user-designed open standard, Health Product Declaration (HPD). 

Here are some general rules of thumb to use when choosing flooring installation materials:
  • When feasible, avoid using an adhesive altogether or prefer a peel and stick option. Several chemicals commonly found in adhesive formulations are hazardous, and the specific chemicals used are not often disclosed. The best option is to avoid using adhesives when possible or to use one that does not react on site, like a peel and stick adhesive.
  • Avoid epoxy and polyurethane adhesives. These adhesives are based on inherently hazardous chemicals including endocrine-disrupting bisphenol A (BPA) and asthmagenic isocyanates.  
  • If using a wet-applied adhesive, prefer those with both low VOC content and emissions.[3] South Coast Air Quality Management District (SCAQMD) Rule 1168 requires most indoor flooring adhesives to have ≤ 50 grams per liter of VOCs. In many cases, products with even lower levels of VOC content are available. For VOC emissions, look for products that meet the California Department of Public Health (CDPH) Standard Method for Testing and Evaluation of VOC Emissions. Considering both VOC content and VOC emissions can help reduce potentially hazardous exposures for occupants and residents, but keep in mind that these standards only capture a handful of hazardous chemicals. Use the rules of thumb and the hazard spectrum below to help avoid other chemicals of concern.

Mechanical fasteners, such as nails or staples, do not typically contain chemicals of concern. Purchase products that can be installed mechanically, such as wood flooring that is nailed in place.

Peel and stick adhesives are solid-state adhesive strips or squares that adhere some flooring materials to their substrates. They can be factory applied to some products or can be sold separately.  

Unlike wet-applied adhesives, peel and stick adhesives are fully reacted and no longer contain reactive substances that would otherwise be released upon application.[4] They may contain some chemicals of concern, like alkylphenol ethoxylates (APEs).[5] Many APEs have been shown to have endocrine-disrupting properties.[6]

By using interlocking tiles, flooring adhesives can often be avoided. In some cases, manufacturers may suggest the use of an adhesive on a portion of the tiles as part of the installation method. Be sure to review product literature for this information. Interlocking tiles often have one or more additional layers added to the floor to allow the tiles to lock together. The materials used for these backing layers can vary. Some, like linoleum, contain a combination of high density fiberboard (HDF) and cork.[7] As with other composite wood materials, HDF can be made using a variety of types of binders. Product literature suggests that linoleum floating floors use an HDF with no added formaldehyde (NAF), which is a preferred binder option.[7] See the Composite Woods Hazard Spectrum for more information. The cork backing may additionally contain a potential respiratory sensitizer.[8]

For other types of interlocking tiles, the backing is often polymer-based and contains fillers like wood dust or limestone and other additives.[9] The specific polymer is often not disclosed. Different polymer materials pose different concerns in terms of potentially hazardous residual catalysts or monomers in the finished product and in terms of life cycle impacts. Those that avoid vinyl are preferred - see Interlocking Tiles (vinyl) below. 

By using interlocking tiles, flooring adhesives can often be avoided. In some cases, manufacturers may suggest the use of an adhesive on a portion of the tiles as part of the installation method. Be sure to review product literature for this information. Interlocking tiles typically have one or more additional layers added to the floor to allow the tiles to lock together. 

Vinyl interlocking tiles typically use a large amount of polyvinyl chloride (PVC) in the click component, so there is more PVC than in a standard vinyl floor. The backing also contains fillers like wood dust or limestone and other additives.[10] The toxic processes required to make PVC and the toxic pollution created when it is disposed of prevent vinyl from being a preferred material. However, because of the hazardous content common to wet-applied flooring adhesives and the fact that they are reacting when applied, an interlocking tile is still preferable to wet-applied adhesives if you must use a vinyl flooring product.

Glue-down carpet, resilient flooring, and engineered wood flooring manufacturers commonly recommend or require the use of acrylic adhesives. These products are typically water-based, 1-part formulations that react on site after they are applied. Adhesives described as acrylic can vary significantly in their formulations. They tend to be low in VOCs, but may contain other hazards including small quantities of asthmagenic isocyanates. Hazardous phthalates may be used in some acrylic flooring adhesives, so make sure to prefer those that are phthalate-free.

Specialty acrylic adhesives can contain hazardous flame retardants or additives to make them more resistant to freezing and thawing cycles. When specifying acrylic adhesives be alert to advertisement of performance attributes beyond what is typical in a more universal product.

Epoxy flooring adhesives are often used to adhere linoleum, vinyl tiles, rubber tiles, or rubber sheets to a variety of flooring substrates. Epoxy chemistries require the use of high hazard substances, including a resin based on bisphenol-A (BPA), nonylphenols , and chemicals known as amines, many of which may contribute to respiratory effects including the onset of asthma. BPA is a developmental toxicant and endocrine disruptor that has been targeted for removal from children’s products.[11] Nonylphenols, part of the larger chemical group of alkylphenols, are endocrine disruptors that have been a focus for priority action by EPA for their health effects.[12]

These adhesives come as a two-part system that must be mixed and reacted on-site. Once applied, the adhesive must set for 12-72 hours after flooring is installed before it can withstand heavy foot-traffic.

Polyurethane flooring adhesives are often used to install solid or engineered wood, bamboo, parquet, and some rubber and vinyl flooring. These flooring types must be adhered to a concrete substrate in many cases. Polyurethane adhesives are available in both a one-part moisture cure adhesive or a two-part adhesive that must be mixed together on site. Single component polyurethane adhesives cure using moisture in the ambient air and therefore set more slowly than 2-part adhesives.  

Polyurethane adhesives are solvent-based and can contain toxic organotin catalysts that can be reproductive toxicants. In addition, polyurethanes contain isocyanates which are potent asthmagens. By touch and through the air, installers and residents may be exposed to these substances as the adhesive is installed and reacts.[13]

Endnotes
[1] Unless otherwise noted, product content and health hazard information is based on research done by Healthy Building Network for Common Product profiles, reports, and blogs. Links to the appropriate resources are provided.

[2] Tarkett. “Can Linoleum Be Recycled?” Accessed August 14, 2019. https://professionals.tarkett.com/en_EU/node/can-linoleum-be-recycled-3466.;  Beth Miller. “CARE Report: Carpet Reclamation Is a Challenge, but Recycle Rates Are Expected to Climb - June 2018.” Accessed August 14, 2019. https://www.floordaily.net/floorfocus/care-report-carpet-reclamation-is-a-challenge-but-recycle-rates-are-expected-to-climb-june-2018.

[3] SCAQMD Rule 1168 (used in many green building standards) requires most indoor flooring adhesives to have ≤ 50 grams per liter of VOCs. Products with ≤ 25 g/L VOC typically qualify as "super-compliant" within the SCAQMD rule. 
The standard most often used to set limits on VOC emissions is the California Department of Public Health (CDPH) Standard Method for Testing and Evaluation of VOC Emissions (formerly called California 01350). The standard uses a small scale chamber test to determine emission of VOCs from products, with measurements taken at 14 days after adhesive application. Results of the small scale testing are modeled to represent different real world scenarios. The most protective is the residential scenario, and this should be preferred if available. Most certifications now available are for the less protective school or private office scenarios. Programs that certify the CDPH Standard Method or a variation of the standard include the industry certifications, Resilient Floor Covering Institute FloorScore and Carpet & Rug Institute Green Label Plus, and independent certifications GreenGuard Gold, SCS Indoor Advantage Gold, and Berkeley Analytical Clear Chem.

[4] Hoff, Susanne Marie, and Leo Ternorutsky. Plasticizer resistant emulsion acrylic pressure sensitive adhesive. US6066394A, issued May 23, 2000. https://patents.google.com/patent/US6066394.;;  3M Industrial Assembly & Design. 3MTM Pressure Sensitive Adhesives Overview. Accessed July 8, 2019. https://www.youtube.com/watch?v=eXysfAhYdOQ.

[5] Hoff, Susanne Marie, and Leo Ternorutsky. Plasticizer resistant emulsion acrylic pressure sensitive adhesive. US6066394A, issued May 23, 2000. https://patents.google.com/patent/US6066394.; “ABEX EP 120 Product Data Sheet.” Rhodia, March 2010. https://www.pharosproject.net/sources/viewFile/31596.

[6] The APE chemical group includes nonylphenol ethoxylates (NPEs) and octylphenol ethoxylates (OPEs). Nonylphenol ethoxylates and their degradation products, nonylphenols, are on the EU Candidate List of Substances of Very High Concern due to endocrine-disrupting properties. https://echa.europa.eu/candidate-list-table. Nonylphenol ethoxylates and octylphenol ethoxylates and their degradation products, nonylphenols and octylphenols, are on the ChemSec SIN List for endocrine disruption (https://sinlist.chemsec.org/) and on The Endocrine Disruption Exchange for potential endocrine disruption (https://endocrinedisruption.org/interactive-tools/tedx-list-of-potential-endocrine-disruptors/search-the-tedx-list).

[7] “Marmoleum Click Cinch LOC.” Forbo Flooring Systems, 2017. https://forbo.blob.core.windows.net/forbodocuments/36550/Click_2017_Brochure_web.pdf.

[8] Forbo Flooring Systems. “Corkment Declare Label.” International Living Future Institute. Accessed June 10, 2019. https://living-future.org/declare-products/corkment/.; Gum rosin is a respiratory sensitizer per Japan GHS and Collaborative on Health and the Environment.

[9] Chen, Hao A., John M. Whispell, and Ji-Min Wan. Floor covering with interlocking design. US8006460B2, issued August 30, 2011. https://patents.google.com/patent/US8006460B2/.; Tucker, Reginald. “Inhaus Looks to Break New Ground with Sono Launch.” Floor Covering News, January 9, 2017. https://fcnews.net/2017/01/inhaus-looks-to-break-new-ground-with-sono-launch/.; “Good to Know.” wineo. Accessed October 4, 2019. https://en.wineo.de/products/purline-organic-flooring/knowledgebase/.

[10] “Wood-Plastic Composites - an Overview | ScienceDirect Topics.” Accessed July 8, 2019. https://www.sciencedirect.com/topics/materials-science/wood-plastic-composites.;  “Rigid Core Vinyl Flooring: SPC vs. WPC.” Parterre Flooring Systems, July 30, 2018. https://parterreflooring.com/spc-wpc-commercial-flooring/.;  “Frequently Asked Questions.” NovaFloor Luxury Vinyl Tile (blog). Accessed July 8, 2019. https://novafloor.us/frequently-asked-questions/.; Chen, Hao A., John M. Whispell, and Ji-Min Wan. Floor covering with interlocking design. US8006460B2, issued August 30, 2011. https://patents.google.com/patent/US8006460B2/.

[11] Nutrition, Center for Food Safety and Applied. “Bisphenol A (BPA): Use in Food Contact Application.” FDA, April 26, 2019. http://www.fda.gov/food/food-additives-petitions/bisphenol-bpa-use-food-contact-application.

[12] “Risk Management for Nonylphenol and Nonylphenol Ethoxylates | Assessing and Managing Chemicals under TSCA | US EPA.” Accessed June 25, 2019. https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/risk-management-nonylphenol-and-nonylphenol-ethoxylates.

[13]  Lott, Sarah, and Jim Vallette. “Full Disclosure Required: A Strategy to Prevent Asthma Through Building Product Selection,” December 2013. http://healthybuilding.net/uploads/files/full-disclosure-required-a-strategy-to-prevent-asthma-through-building-product-selection.pdf.

Last updated: October 10, 2019