Balconies and terraces, in some cases high above the street, are commonly exposed to damaging conditions including extreme cold, wind, driving rain, snow, sleet and intense ultraviolet exposure. All of this exposure takes place within feet of living quarters. Battered by continual exposure, pollution, building movement and frequent use, attention to connections such as deck and door thresholds, deck and door jambs and other transitions between the balcony and wall is critical to seal out weather while sealing in comfort and energy savings. Premature failure at the interface of the deck coating and the adjacent door and/or window system on high-rise, cantilevered, cast-in-place concrete balconies and the resulting moisture penetration cause more extensive deck coating failures and subsequent deterioration to the underlying concrete substrate.
Even minor problems can escalate into major issues if not addressed. Spot repairs are only temporary repairs and may not address all the underlying conditions, but balcony repairs can be expensive as well as extremely inconvenient and disruptive to tenants.
New technologies are offering alternatives that help minimize disruption while providing tested, documented performance demonstrating their ability to provide sustained protection.
Creating a high-performance seal from door to wall, door thresholds
Weeps in frame systems allow water in the glazing pockets or balcony door to drain, and any conditions in the framing and interior glazing gaskets that have become unsealed provide an air path to the interior. As the elements take their toll, the building moves, and occupants step on the door threshold while stepping onto the balcony or back into the interior of the building. Seals are then broken, allowing air and moisture infiltration. Moisture migrating through or forming within the building envelope from condensation can damage interior components, lead to occupant discomfort and increase energy consumption for heating/cooling.
Restoring weatherproofing reliability and functionality can take many forms. Some may be short-term fixes that will lead to perpetual maintenance. More permanent fixes may be more disruptive or costly. The T3 Building Envelope Solutions provide a three-level, high performance sealing system for around windows and doors. This allows differential movement between dissimilar building materials while creating a connection that takes into consideration thermal insulation as well as protection from air and water infiltration. With the ability to stay flexible despite the abuse taken at the bottom of a balcony door and its unique ability to provide an airtight separation for the interior environment, the decision was made to test for performance when subjected to wind-driven rain and air leakage.
Minimizing disruption from balcony deck recoating
Even small, hairline cracks in the concrete of a balcony can be problematic. The most common place for deterioration to begin is at the connection details. All cracks, no matter how small, will allow water to penetrate the concrete. In colder climates, as the temperature drops, water that has penetrated the cracks freezes and expands to create more cracks. Over time, as the cycle continues, the water penetration can also affect the steel reinforcement frame of the balcony causing it to rust and also causing concrete spalling.
Traditional balcony recoating takes a minimum of three days - a day for application of base coat, another for application of top coat and a day to properly cure. At times, access from the building interior is not possible, requiring some form of lift equipment that adds cost. Technology developed by Tremco Commercial Sealants & Waterproofing in the form of a one-coat polyurethane coating for light pedestrian traffic combines the flexibility and adhesive properties of a base coat material and the UV protection and wear-resistance of a top coat material - all in one product - eliminating time, cost and disruption.
Since the connection details are critical to the success of the restoration, sealants used with the deck coating system must be not only be compatible, but also provide the same movement capability. With exceptional movement capability (+100/-50), Tremco's Dymonic® 100 Polyurethane Sealant is ideal for the demands of balconies and is compatible with Tremco air barrier products and deck coating systems.
When put to the test for wind-driven rain (ASTM E331) for a total of 67 minutes, stepping from a minimum pressure of 300 Pa to 2100 Pa, there was never any water leakage in this balcony assembly.
When tested for air leakage after wind conditioning in accordance with ASTM E2357 in high-wind geographic regions, air leakage was measured to be 0.021 cfm/ft², basically half of the allowable amount specified by the Air Barrier Association of America for an air barrier assembly (0.04 cfm/ft² or less). Having an assembly that meets these requirements and the criteria of the International Energy Conservation Code (IECC) provides confidence in the integrity of the resulting thermal.
Balcony-to-Wall and Wall-to-Balcony Door Connectivity Test Report
Contact your local Tremco sales representative to find out how to transform your built environment into a high-performance environment.