Which type of sealant is recommended around penetrations of masonry block or wood foundation walls?

Elastomeric sealants are recommended for use around penetrations of masonry block or wood foundation walls due to their unique properties that make them well-suited for such applications. These sealants are highly elastic, allowing them to accommodate movement and expansion in the materials they are sealing. This is particularly important around foundation penetrations, where temperature fluctuations, settling, and moisture changes can cause movement in the structure.

The flexibility and ability of elastomeric sealants to recover from deformation mean they can maintain a tight seal even as conditions around them change. This characteristic helps prevent the ingress of radon gas and moisture, ensuring a better seal for the integrity of the structure and maintaining indoor air quality.

In contrast, options like acrylic sealant may not provide the same level of elasticity and can become brittle over time, which may lead to cracking and failure of the seal. Silicone sealants, while flexible, may not adhere well to porous surfaces such as masonry block. Therefore, elastomeric sealants are considered the most effective choice for sealing around foundation penetrations in both wood and masonry walls.