Understanding the cause (e.g., poor ventilation) is the first step toward preventing condensation. Listed below are a number of steps that can be taken to reduce the potential for moisture buildup.
1. Always make sure round holes are cut in the roof deck, whether using the self-flashing or the curb-mounted cap. Square holes cut in the roof deck will let too much warm, moist air into the flashing or curb cavity.
2. Install a flashing insulator or curb insulator. These reduce the amount of warm air from the building’s interior that contacts the cold, metal interior of the flashing. On a curb-mounted unit, attach the curb insulator to the interior base of the curb, centering it over the round hole in the roof deck.
3. For self-flashing units, pack insulation material into the space between the flashing and the tubing to reduce the volume of warm, interior air that contacts the cold metal of the flashing. With curb-mounted units, push insulation into the curb cavity. Filling the curb cavity’s air space will equalize the temperature and reduce the occurrence of condensation. The Solatube® Curb Cap Insulation Kit is also recommended and provides R-6 rigid insulation at the underside of the curb cap. For the Solatube SkyVault® Series, rigid insulation is pre-installed in the roof assembly.
4. If a curb or flashing insulator is not used, another option is to seal the penetration where the tubing comes through the roof deck with an expanding foam sealant, insulation, or other similar product. This will reduce the chances of warm, moist air making contact with the interior of the flashing or curb cavity.
5. Ensure the dome is correctly attached to the flashing or curb cap, including dome seals in certain models. Solatube Daylighting Systems are designed to allow some air transfer from the interior of the system to the exterior. This allows moist air to vent, while enabling any droplets of water that may form on the dome to escape
6. In extreme cold climates, wrap the tubing in insulation. For best results, use foil-faced insulation. Be sure to insulate the entire tube run from the roof deck to the ceiling plane, leaving no gaps in the insulation. You can also use this method in extremely moist environments in an open ceiling application.
7. If a vapor barrier is present when penetrating the roof deck, ensure that it is maintained and sealed off once the Solatube Daylighting System has been installed.
For more details on how to address condensation, please contact your Solatube daylighting expert.