What is Elastomeric Sealant?

Elastomeric sealant is a building material used to fill and seal up spaces. With a rubbery liquid texture that dries hard but retains flexibility, it can be easy to work with and is typically long lasting. When applied or inserted into a crack or space, the sealant expands and seals to the surface, creating a waterproof barrier. It is barely visible or invisible on most materials, and may be used indoors or out.

A chemical compound, or polymer, called elastomer makes up elastomeric sealant. It is strong and spongy-hard and rubbery, making it an elastic polymer. Typically it comes in a tube, tub or can and is semi-liquid and creamy, which makes it very malleable for application by hand or with a caulking gun. Hardware and specialty stores that carry building materials usually stock sealants.

Projects ranging from small, do-it-yourself varieties to large professional jobs can utilize elastomeric sealant. Sealing cracks in floor boards and around windows in homes may be useful for insulating against drafts or water seepage. Repaving driveways or sidewalks and curing the spaces between poured slabs is another use. It can be well suited for situations where a structure needs to retain its ability to expand and contract while still bearing heavy loads, such as in a floor or on a driveway.

Often elastomeric sealant is applied by squeezing it into a space until it fills up to the top or out of the edges. After being pressed in or left to settle, it actually fills in the small gaps and spaces within the crack or larger fissure itself. As the sealant dries, it can shrink some, but according to the American Society for Testing and Materials, which tests sealants and publishes product standards, it should not shrink more than 7 percent, and it should not crack or come apart from the edges when bearing weight. It also should be waterproof.

Caulking projects also may benefit from using elastomeric sealant because of its flexibility cosmetically. It can be left to dry in its clear or milky translucent form, or it can be painted to blend in with the bonded material, weather metal, concrete, glass, or wood. Due to its ability to flex with a material’s movement, elastomeric sealant also is effective in varying climates where expansion and shrinking can occur.