Foundation waterproofing and above-grade air/moisture barriers both form critical pieces of the building envelope. The at-grade transition where they meet is an often-overlooked detail susceptible to air and moisture infiltration.
This detail addresses sealing the interface between the foundation and wall. It is not an alternate to, or option to eliminate, the Code-required flashing at the foundation (IBC 1404.11.1.3). That flashing must be integrated as part of the wall assembly and can function as the transition material between the waterproofing and air-barrier.
- Floor Line Gaps
- Below grade Waterproofing
- Air Moisture Barriers
- Above Grade Waterproofing
- Landscaping Coverings
How to Properly Seal the Gap Between Foundation and Walls
Wall to Floor Line Gaps Must Be Sealed
The transition between foundation and wall often presents a gap susceptible to air and water infiltration. Gaps and out of plane transitions often require specific details to support the air barrier membrane.
Below Grade Waterproofing Transition Materials Must Be Chemically Compatible
Air barrier and waterproofing systems are comprised of proprietary primers, adhesives and solvents that may not be chemically compatible. If the products have not been tested for compatibility, an inert transition material such stainless flashing membrane should be provided between the systems.
Air Moisture Barriers Must Terminate Above Grade
Air barriers installed on vertical walls are not typically rated to resist ponding water, frequent wetting, and capillary moisture found at-grade conditions. The air barrier to waterproofing transition should be held 6-8” above finished grade.
Above Grade Waterproofing Should Be Protected from UV Exposure
While effective at resisting moisture and hydrostatic head, waterproofing systems typically require protection from UV exposure. Above-grade waterproofing should be protected by using masonry base-cladding, stainless steel cover-flashing, or a sacrificial and replaceable cover material.
Waterproofing Termination Should Extend Above the Final Landscaping Coverings
Landscape coverings may retain water or inhibit drainage away from the foundation. The height of these materials should be considered when determining the elevation of the waterproofing transition.
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To learn more about the importance of transitioning air barriers, contact us and one of our consultants will be happy to talk with you. We’re here to help you avoid risks and achieve a high preforming facade.