Aluminum skylights and curtain wall notes
Last updated October 11, 2024
By Emma Howland
Curtain Wall: thin, usually aluminum-framed wall, containing in-fills of glass, metal panels, or thin stone. The framing is attached to the building structure and does not carry the floor or roof loads of the building.
Curtain wall systems
- Stick systems: curtain wall frame and glass are installed and connected piece by piece
- Unitized (or modular) systems: curtain wall is composed of large units that are assembled and glazed in the factory, typically one story tall by one module wide.
- Face sealed: Depend on continuous and perfect seals between glass units and the frame between all frame members. Long-term reliability of such seals is extremely suspect and should be avoided.
- Water-managed: the second most resistant to air and water infiltration
- pressure-equalized rain screen: the most resistant to air and water infiltration. block all forces that can drive water across a barrier-This is done by making the inside face of the glazing pocket and the interconnecting gasket an airtight barrier. The outside face of glass, exterior glazing materials and exposed aluminum function as a rain screen. The glazing pocket acts as a a pressure-equalization chamber. small amounts of water that may penetrate the system weep to the exterior. The glazing pocket around each individual unit of glass is isolated air tight from adjacent units, most obviously with plugs or seals at the gaps in between screw splines at mullion intersections.
- Water Managed systems: incorporate drains and weeps from the glazing pocket. No air barrier exists, so the pressure differential between the glazing pocket and the interior may create a strong enough pressure to force water vertically higher than the interior gaskets resulting in leaks.
Thermal Performance:
- Proper placement of insulation at the curtain wall perimeter reduces energy loss and potential condensation issues. Insulating the mullions in a spandrel area may lead to excessive condensation in cold climates. Do not insulate between the interior portion of mullions and adjacent wall construction.
Moisture Protection
- Mitigating water infiltration must account for 5 different forces: gravity, kinetic energy, air pressure difference, surface tension, and capillary action
- The key is watertight frame corner construction and good glazing pocket drainage
Back Pans: aluminum or galvanized steel sheets attached and sealed to the curtain wall framing around the perimeter behind opaque areas of a curtain wall. Provide a second layer or protection against water infiltration that are not visible from the interior and are difficult to access.
