Considerations for Choosing Flooring Adhesive

Glued down hardwood floor: Thinset mortar and trowel
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Flooring adhesive is any type of strong, permanent glue for adhering flooring materials to a subfloor or underlayment. Different types of adhesive are recommended for different types of flooring, although some multi-purpose solutions can be used effectively with multiple materials. There are several factors to consider when choosing a flooring adhesive for your project. For detailed product information, refer to the product's specification sheet.

Substrate

The substrate is the structure or material directly below the finish flooring. Certain adhesives will bond better to different types of subflooring. Damp below-grade concrete requires a different bonding material than flooring installed on dry at- or above-grade concrete. Some adhesives also can be used to install flooring over plywood subflooring, and there are specific hardwood bonding agents as well. You may also need a specialty adhesive if radiant heating is being installed.

Location

Interior installations are generally not subject to large amounts of weathering and water damage. If you are going to be installing in an exterior environment, you will need a flooring adhesive that can handle the stress of rain, sun, snow, and cold. Climate also plays a role, as some adhesives do better in warm, humid areas, while others are formulated to withstand freezing temperatures.

"Recommend For"

"Recommended for..." is a term that you will often find on adhesive packaging and instructions. It refers to what the product is specifically designed to be used for as far as material, substrate, and environment. In some cases, this will be followed by the term “but can be used for,” which refers to situations where the product can work but might not be as effective as other solutions. It's best to use an adhesive specifically designed for your type of application.

Toxicity

Volatile organic compounds (VOCs) are toxic materials that are sometimes off-gassed from certain chemical flooring adhesives. These particles can be harmful to the indoor air quality of a space and can exacerbate asthma and other respiratory problems. Many types of adhesive are available with differing levels of VOCs. If this is an important consideration for you, compare similar products, and choose the one with the lowest VOC content.

Self-Adhesive Tiles

Some types of resilient flooring, including vinyl, cork, and linoleum tiles, are available with self-adhesive backing. That means that installation simply requires peeling off a protective paper layer to reveal adhesive already in place. The tile is then pressed into place without the requirement of any additional adhesive.

Drying or Curing Time

How fast an adhesive dries or cures will determine how much time you have to install the flooring and, if the adhesive requires mixing, the amount of adhesive you will have to prepare at each stage. It also determines how long you will have to wait before you can actually walk on the surface of the floor without having to worry about the materials moving.

Consistency

Consistency refers to how well the adhesive grips to the trowel or other application tool and how easy it is to spread it out across the substrate. Too thin, and the material will wash out, making it difficult to work with. Conversely, an overly thick adhesive can be very hard to spread.

Coverage

When deciding how much adhesive you will need for a flooring installation project, you should consider the size of the space and then add 10 percent to that for waste. Most adhesive packaging will clearly state how large an area it is estimated to be able to cover.

Shelf Life

Depending on when the project takes place, you may have to consider shelf life. Some adhesives can be stored for years and used without any degradation of quality. These can be kept in stock in case you need to perform repairs. Some chemical adhesives will have a relatively short shelf life with their ability to bond diminishing over time.

Cleanup

The adhesives used in a flooring installation project can be some of the most difficult things to clean up and remove from surfaces. In general, water-based glues are easier to clean up than solvent-based adhesives, but water-based materials may be more susceptible to moisture damage.

Flooring Adhesive Precautions

Always follow all of the manufacturer's instructions when using a flooring adhesive. The adhesive used should be specifically noted as being appropriate for the material, substrate, and environment of the project at hand. Make sure the installation area is well-ventilated. When using toxic materials, run fans and wear a mask or respirator to improve air quality and protect your lungs. Goggles and gloves are also recommended to protect your skin and eyes.