VOCs and Roof Membrane Bonding Adhesives

Volatile Organic Compounds (VOCs), along with Nitrous Oxide (NOx), are compounds which react with UV rays from the sun to produce ozone. Increased levels of ground-level ozone can affect overall air quality. Restrictions began in 1970s California due to Los Angeles' increasing smog problem and were followed by the development of the Ozone Transport Commission (OTC) in the 1990s. The OTC is an organization made up of northeastern states: Connecticut, Delaware, the District of Columbia, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Virginia. Both California and the OTC set limits for the overall content of NOx and various VOCs in products such as cleaners, paints, adhesives, and aerosol products. Often, this content is expressed as a number of grams per liter (g/l) or a percentage of VOCs by weight of product.

There are adhesives being made today with VOCs, and others that are low-VOC, water-based, or VOC-free. The differences in these adhesives depend on their formulations and dispensing methods. The most important thing to keep in mind is that low-VOC or water-based adhesives are different from standard bonding adhesives and will react differently during application.

Generally, low-VOC or water-based bonding adhesives will take longer to dry due to the higher water content (depending on the outdoor temperature and humidity level). Also, low-VOC and water-based adhesives may have cold weather restrictions and be more prone to freezing. Refer to the product data sheets for each bonding adhesive to determine any installation precautions for the adhesive you choose.

Keep in mind, not all low-VOC adhesives have application temperature restrictions. CAV-GRIP® III, a low-VOC adhesive, is dispensed using a spray gun attached to a portable cylinder and can be dispensed in temperatures as low as 25°F (-4°C).

VOC-free or no-VOC bonding adhesives may not have the same restrictions as low-VOC or water-based adhesives, as they are dispensed or used in a way that does not involve a medium which needs to “flash-off” before the adhesive becomes tacky.

As an example, Flexible FAST Adhesive is a low-rise polyurethane adhesive with two parts. Part A and Part B are catalyzed together in the dispensing equipment to create a chemical reaction and "create" the bonding adhesive as needed in the field. This method produces heat as a byproduct and does not have the same low-temperature restrictions as most water-based adhesives and also contains no VOCs.

Always select the bonding adhesive designed specifically for the membrane or insulation you're using, then select the adhesive that meets your project's goals for VOC thresholds. There is an adhesive for every membrane and every project that will deliver the performance and VOC levels you need.

Consult the Product Reference Guide on the Carlisle SynTec website or contact Craig Tyler at [email protected] with questions.