Water intrusion at wall-to-foundation intersections is the movement of water into the interior where the exterior framed wall and foundation meet.
The wall-to-foundation intersection is vulnerable to water intrusion, because it's a location where two different materials meet; water can enter the home through the gap between them. Wind-driven rain can be forced under or through the exterior finish at the intersection. And water moving down the drainage plane can wick under the sill plate if the housewrap is cut too short. Water that enters where the wall meets the foundation can contribute to structural issues with the wall assembly and cause damage to interior floor finishes. To prevent water from entering the wall-to-foundation intersection, the housewrap must bridge the gap.
Weep screed for stucco
If the exterior finish is stucco, water can enter at the intersection if the weep screed is missing or improperly integrated with the drainage plane. The weep screed is installed at the bottom of the stucco finish, allowing any water saturating the stucco to drain to the outside. Without this protection, water may build up and wick into the wall.
Cause 1:
Improper layering of housewrap over the foundation
Water intrusion at the wall-to-foundation intersection can happen if the housewrap doesn't layer over the foundation by the correct amount. Housewrap that's cut short will allow water to enter under the sill plate. Wind-driven rain can be forced under or through the exterior finish at the intersection.
Solution
To keep water from moving into the intersection, make sure the housewrap layers over the foundation by at least 1".
Cause 2:
Improper integration of weep screed with the housewrap
Water won't drain freely to the exterior if the housewrap is layered behind the weep screed or if the housewrap is cut too short to properly layer over the weep screed.
Solution
The housewrap should layer over the foundation by at least 1". Cut the housewrap, and fold it up and out of the way. Install the weep screed, layering over the foundation wall by at least 1" as well; then, fold the housewrap down, layering it over the weep screed.
