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Detailing and integration of the vertical building façade system and the below-grade waterproofing system is of critical importance to the overall performance of the building enclosure. The majority of building enclosure failures can be related back to an interface that was either poorly or not appropriately detailed, or not detailed at all. There are numerous details that must be addressed, but there are some that can be extremely damaging, yet do not receive the same attention including:
Façade terminations often produce the accumulation of moisture at or near the grade line of the building with the surrounding area. At the connection from the above-grade to the below-grade walls, the connection detail needs to be addressed and this may include a ledge. A special flashing and treatment of the exterior slab edge where it is adjacent to grade line or ground features is required. While there is limited movement at these joints, the compatibility/adhesion and the ability of overlapping layers to provide a durable weather barrier despite surface water, runoff and cavity wall drainage is essential to the control of moisture, air and thermal performance.
A fully integrated and effective air barrier system should include details for each unique interface, penetration or transition. Inside and outside corners present challenges that may be just as critical to the ultimate longevity and success of the enclosure as other more commonly acknowledged transitions. For inside corners, tenting of sheet-applied membranes or gaps with spray-applied membranes leave a natural path for water infiltration. With outside corners where two walls come together, the connection needs to be durable and proper mil thickness needs to be maintained.
Putting Performance to the TestTo determine connectivity solutions that would perform long-term, a wall assembly was put together containing seven different connections. These included:
Testing was then conducted at the Tremco Sustainable Building Solutions Test Facility and pushed until failure:
When tested in accordance with ASTM E2357, no damage was witnessed during the duration of the testing and air leakage was at 0.0026 cfm/ft² at 75 Pa. When testing was conducted for ASTM E331, water leakage did not occur until 1750 Pa, or a simulated 121 mph wind load equivalent to a Category 3 hurricane, had been maintained for 4 minutes and 30 seconds. This was far beyond the standard test requirements at 300 Pa (6.24 psf).