What is the minimum membrane thickness required for waterproofing a masonry foundation wall with polymer-modified asphalt?

The minimum membrane thickness required for waterproofing a masonry foundation wall using polymer-modified asphalt is indeed 40 mil. This thickness is necessary to ensure adequate protection against water infiltration and damage to the foundation structure. Polymer-modified asphalt provides improved adhesion and flexibility compared to traditional asphalt, which makes it particularly effective for waterproofing applications.

A thickness of 40 mil is significant because it offers the durability needed to withstand various environmental conditions and stresses that a foundation wall may encounter, such as soil pressure and potential hydrostatic pressure from water. This standard helps ensure that the waterproofing layer will be effective over time, preventing leaks and maintaining the structural integrity of the building.

Thinner membranes may not provide sufficient protection, as they could be more susceptible to punctures, tears, or degradation over time. Consequently, adhering to the 40 mil requirement helps ensure that the waterproofing system performs as intended and lasts for the expected lifespan of the building.