Damp proofing spray is a protective, tar-based coating applied directly to concrete foundation walls to help prevent ground moisture from penetrating the foundation. It is typically applied to the exterior of the foundation once the concrete forms have been removed and the wall surface has been properly prepared.

Building code requirements specify that a minimum of one coat of exterior damp proofing spray must be applied to foundation walls. This coating acts as a basic moisture barrier, reducing the amount of dampness that can migrate through the concrete and into the foundation structure. While damp proofing is not a waterproofing system, it plays an important role in limiting moisture absorption and protecting the foundation from long-term exposure to soil moisture.

In addition to exterior application, damp proofing spray can also be applied to the interior foundation walls. Interior damp proofing provides an added layer of moisture protection and can be especially beneficial in basements prone to damp conditions or minor seepage.

One key advantage of interior application is its ability to help seal the joint where the foundation wall meets the basement floor. This joint is a common entry point for moisture, and sealing it can significantly reduce dampness and minor water intrusion.