Red Seal Glazier key terms

Heat-treated float glass cooled rapidly so the outer surfaces compress and the core stays in tension. It breaks into small granular dice and is about four times stronger than annealed glass of the same thickness.

Glass heated and cooled under controlled conditions to roughly twice the strength of annealed glass. It fractures in larger, more radial pieces than tempered glass and is not classified as a safety glazing product.

Ordinary float glass cooled slowly under controlled conditions to relieve internal stress. It is the base product for most fabrication and breaks into large, sharp shards, so it cannot serve as safety glazing.

Two or more glass plies permanently bonded to a plastic interlayer, usually PVB or ionoplast. The interlayer holds fragments in place after breakage, so the unit stays in the opening and qualifies as safety glazing.

The thermoplastic sheet, commonly 0.38 mm or 0.76 mm thick, used to bond glass plies in laminated glass. It provides the post-breakage retention and sound-damping properties of the assembly.

A stiff, ionomer-based bonding sheet used in laminated glass. It offers higher stiffness and post-breakage strength than standard PVB and is often specified for structural or overhead laminated assemblies.

A factory-sealed assembly of two or more glass lites separated by a spacer and a dry-air or gas fill. The sealed cavity reduces heat transfer and condensation compared with a single pane.

A microscopically thin metallic or metal-oxide film applied to glass that reflects long-wave infrared radiation. It lowers the U-value and, depending on which surface it faces, controls solar heat gain.

A low-emissivity coating applied after the glass leaves the float bath, usually on a sputter coater. It performs better than hard coat but is delicate, so it normally sits on a protected cavity surface of an insulating unit.

A low-emissivity coating applied while the glass is still on the float line, giving it durability and handling resistance. Its emissivity is somewhat higher than soft coat, and it can be used on exposed surfaces.

The rate of heat flow through a glazing assembly per unit area per degree of temperature difference. Lower values mean better insulation; in metric practice it is expressed in W/m²·K.

The fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed then released inward. Values run from 0 to 1, with lower numbers meaning less solar heat gain.

The percentage of visible-spectrum light that passes through a glazing assembly. It is balanced against solar control and shading choices when selecting glass for daylighting and glare.

Glazing that meets the impact test requirements of the applicable building code, resisting breakage or breaking into patterns unlikely to cause serious injury. Tempered, laminated, and certain wired glasses qualify.

Opaque or back-coated glass used in the vision-free bands of a curtain wall to conceal floor slabs and structure. Ceramic frit or an opacifier is applied so the glass reads as a solid colour from outside.

The transparent portion of a curtain wall or window wall through which occupants see out. Its size and placement set daylighting, views, and the visual rhythm of the façade.

A non-load-bearing exterior wall, usually of aluminium framing and glass, that hangs from or is anchored to the building structure and carries only its own weight plus wind and seismic loads.

A curtain wall erected piece by piece on site: mullions and transoms are installed first, then glazing and infill panels. It suits smaller or irregular projects but demands more field labour and weather exposure.

A curtain wall assembled into large factory-built units, complete with framing and glazing, then lifted and interlocked on site. Factory control improves quality and speed and reduces scaffolding time.

The vertical framing member of a curtain wall, window wall, or storefront that divides glazed areas and carries wind load to the structure. Depth and reinforcement are set by structural calculation.

A horizontal framing member that divides a glazed opening, often separating a vision area from the panel above a door or below a head. It also stiffens the frame against wind load.

A low-rise, non-load-bearing glazed framing system, typically at ground-floor retail or entry, spanning between a base and a header. It is generally not designed for the inter-storey movement a curtain wall handles.

A system in which glass is bonded to the framing with a structural silicone sealant that transfers wind and other loads from the glass to the frame. It allows flush exterior façades with no visible exterior stops.

The width of the structural silicone contact area on the glass, measured from the glass edge inward. Bite width is determined by engineering calculation, not by the sealant bead's visible thickness.

The non-structural silicone or gasket bead that keeps water and air out of a structural silicone joint. It protects the structural bite from moisture and UV but is not counted for load transfer.

Double-sided foam tape that sets and holds the precise structural silicone bite thickness and depth during cure. It also acts as a backer controlling sealant profile and tooling.

A laboratory test in which the structural silicone, spacer tape, gaskets, and glazing accessories are assembled and checked for adhesion and staining before production. It confirms the sealant will bond and cure correctly.

A field or shop check, often a peel or pull test on a cured sealant sample, confirming the silicone bonds to the glass and frame. It verifies surface preparation and cure before the joint is accepted.

A non-conductive separator, usually polyamide or urethane, placed between the inner and outer aluminium profiles of a frame. It interrupts heat flow and reduces condensation on cold frame surfaces.

The flexible gasket, pile, or bulb seal that closes the gap between a window or door sash and its frame. It blocks air and water infiltration and must compress evenly when the unit is closed.

A glazed roof opening that admits daylight into a space below. Because it is sloped or horizontal, it must shed water, resist snow and wind uplift, and use safety glazing where required.

Glazing installed at an angle from vertical, including skylights, canopies, and atrium roofs. It needs positive drainage, weep paths, and laminated or otherwise approved overhead safety glazing.

A channel in a skylight or sloped glazing frame that collects water condensing on the interior and drains it outside rather than letting it drip into the space.

A small opening in the sill or frame that lets trapped water drain to the exterior. It must stay clear of sealant and debris or the frame will hold water and leak.

A neutral-cure adhesive applied in beads to bond a mirror to a wall or backing. It must be non-staining and compatible with the mirror's backing so the reflective coating is not attacked.

The protective coating, paint, or laminated film on the rear of a mirror that shields the reflective layer from moisture and handling damage. Damaged backing leads to black-edge corrosion.

A pressure-sensitive film or fabric applied to the back of a mirror or glass panel so fragments stay attached if it breaks. It is used where the code does not accept ordinary annealed glass.

The top rail that ties the fixed and hinged panels of a shower enclosure together and anchors them to the walls. It carries the door's weight and keeps the enclosure square and rigid.

The hardware that pivots the shower door on the fixed panel or wall, often a glass-to-glass or glass-to-wall hinge. It must be rated for the door's weight and mounted with the correct clearance.

A process that holds tempered glass at about 290 °C for a set period to expose nickel sulphide inclusions, which can cause spontaneous breakage. Panels that fail are rejected before installation.

Failure of tempered glass without apparent impact, usually traced to a nickel sulphide inclusion or edge damage that releases stored tensile stress. It produces the characteristic dice pattern.

Glazing tested to resist windborne debris and, in some assemblies, forced entry or blast. It typically uses laminated glass with a stiff interlayer and a heavy anchoring system.

The pressure or suction exerted on glazing and framing by wind, calculated from building height, exposure, and local code. It sets mullion span, glass thickness, and anchor design.

The mating profiles at the edges of unitized curtain wall panels that engage as units are set, aligning and sealing the joints. Correct engagement controls air and water penetration between units.

A fired ceramic ink applied to glass, often as a dot pattern or full coat, for solar control, visual masking, or spandrel opacification. It is fused into the glass surface during heat treatment.

A drying agent, usually in the spacer of an insulating glass unit, that absorbs moisture inside the sealed cavity and prevents internal condensation and fogging.

A low-conductivity spacer, often a thin stainless or composite profile, that reduces heat flow at the edge of an insulating glass unit. It raises the edge temperature and limits condensation.

A spring-and-damper device that automatically shuts a door at a controlled speed. Its adjustment affects accessibility, latch engagement, and air infiltration at the door.

The fixed surround that receives a door, anchors it to the wall, and carries the hinges and strike. It must be plumb, square, and securely shimmed for the door to swing and latch correctly.