Guide To Avoiding Glass Failure
Glazing Materials
Glazing materials such as gaskets, sealants and tapes are used to
provide a seal, glass cushion and thermal isolation between the glazing material and the
framing system. The function of the glazing material is to keep air, water and other items
from entering the frame/sash area that can cause deterioration of the insulating glass,
the building interior along with other parts of the building wall system.
Three common
glazing materials are discussed.
- Gaskets can be made of solid or foam sections and be of
neoprene, EPDM, vinyl silicone, and other rubber type materials. Gaskets will need to be
resistant to the elements and be able to maintain their elastic and hardness properties to
properly seal and cushion the glass used in the system. Gaskets can be keyed or wedge type
depending on the system and design requirements. Many systems use an interior and exterior
gasket with the thickness, hardness and profile engineered to apply a proper pressure on
the glass with consideration given to tolerance of the glass, frame material, and gasket
dimensions.
- Sealants can be used individually or in combination
with gaskets or tapes. Materials commonly used are silicones, polysulfides,
polyurethanes,
butyls, acrylics and other materials that are gunnable and can be tooled to provide a
designed shape. The proper choice of sealant will depend on such items as the joint size,
expansion/contraction expectations , materials joined/sealed, and the environmental
conditions that the material may encounter. Many sealant types come with various
capabilities that require careful consideration to make certain that breakdown, loss of
adhesion, improper support or lack of proper isolation do not occur.
Close attention to
the performance characteristics and material compatibilities with various surfaces such as
metal finishes, painted substrates, and other gasket/tapes must be considered for proper
design of sealants used in a building wall system.
- Tapes are commonly used in the design of a window system and
provide similar functions as sealants and gaskets. Tapes are provided in solid and foam
materials usually having a rectangular cross section. Tapes can be supplied with adhesive
backing on one or two faces and can also be obtained in a butyl form with or without a
sham. The design of a window system using tapes will require the tape to meet the pressure
conditions expected as well as environmental and compatibility requirements of the
building. Many designs utilize tapes as a back-up to a sealant application, a temporary
cushioning material while sealants are curing or to provide a holding method prior to
applying a final gasket.
Guide
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