glazing
The term ‘glazing’ refers to the action of permanent glass placement in it’s frames. There are 4 primary types of glazing types dependent on the frame and the glass securing element:
Face Glazing – Form of wet glazing when the panes are set in a rabbeted wood frame, kept in place with glazier’s points, and sealed with a bead of putty or a glazing compound.
Glaziers putty is commonly composed of whiting and linseed oil with a ‘dough’ consistency which is used to secure window panes. Glazier’s compound is an adhesive material utilized as putty and produced specifically to reduce brittleness with age. Lites larger than 6 square foot typically cannot be Face Glazed.
Dry Glazing – Placing glass into a window frame with a compression gasket. Fast and less dependent on quality workmanship than wet glazing. Sometimes used in combination with wet glazing.
Structural Gasket Glazing – Placing glass into a window frame with preformed synthetic rubber or other elastomeric material. Gaskets are held by forcing a keyed locking strip into a gasket groove.
Polybutene glazing tapes (butyl, polyisobutylene) are commonly used in glazing and are made up of a sticky synthetic adhered by pressure to glass and mullions.
Wedge gaskets or Roll-in gaskets are also utilized and are an elastic material pushed into the glass/mullion gap from the interior which wedges/seals against leakage.
Wet and dry glazing requires that the glass unit to float in the planned opening and be cushioned with a resilient material on all sides of the lite, maintaining a minimum of 1/8″ clearance from the frame. Said resilient edge blocks are typically made up of resilient rubber and work to center the frame, maintain sealant uniform width, and restrict movement. Edge blocks are 4″ minimum length, minimum width of glass thickness, and placed at quarter points/sides/corners.
The ‘face clearance’ is the dimension between the pane face and the nearest face of it’s frame or stop. ‘Bite’ is the amount overlapped between glass edge and the frame, stop, or lock-strip gasket. ‘Edge Clearance’ is the dimension between the pane edge and window frame. Mullions are structural accents occuring at the joints of the panes meant to hold the glass in place and transfer wind loads down to the structure and away from the glass. Typically weep holes are placed in the sill frame to drain water.
Many stock frames have lites glazed right in at the factory. Specialty frames (especially steel frames) are typically glazed on the job. If the frame design permits, glazing will occur from the inside of the building eliminating the need for scaffolding, cranes, or lifts for upper stories or elevations. For larger glazing projects, the architect will design the glazing parameters to assure the following are being met:
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-Isolate the glass from frame/mullion deflection and permit expansion and contraction of glass and frame
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-Fully support the glass against wind load and suction
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-Fully support the weight of the glass