Glazing
Summary
Glazing is the glass or plastic infill of an opening, specified by strength treatment, lamination, insulating construction, and coatings. Choose glass for wind load, safety, thermal and solar performance, and appearance together, since one product setting heat gain, strength, and breakage behavior must satisfy the glazing rules in the parent note.
Cols
Terminology
- Annealed glass: standard float glass with no strengthening, the most common architectural glass
- Heat-strengthened (HS): heat-treated glass at least twice as strong as annealed; breaks into large shards; not safety glazing by itself
- Fully tempered (FT): heat-treated glass about four times as strong as annealed; breaks into small pieces
- Laminated glass: two or more glass layers bonded with an interlayer
- Insulating glass unit (IGU): sealed assembly of two or more panes with a gas or air space
- Low-e coating: thin coating that reduces heat transfer and solar gain; hard-coat (pyrolytic) or soft-coat (sputtered)
- U-factor, SHGC, visible transmittance: heat transfer, solar gain, and daylight ratings
- Spandrel glass: opaque glass that covers floor edges and structure
Standards
Product standards
- ASTM C1036: annealed flat glass
- ASTM C1048: heat-strengthened and fully tempered flat glass
- ASTM C1172: laminated architectural flat glass
- ASTM E2190: insulating glass unit performance and evaluation
- ASTM E1300: glass load resistance
- NFRC 100 and 200: U-factor and SHGC ratings
Selection
- Safety glazing must pass ANSI Z97.1 or CPSC 16 CFR 1201; heat-strengthened glass alone does not
- Laminated glass behavior after breakage depends on construction, not only the interlayer
- "Low-e" alone does not set performance; compare U-factor, SHGC, and visible transmittance of the whole unit
Materials
- Annealed, HS, and FT glass: monolithic panes by strength and safety need
- Laminated glass: safety, security, and sound control
- Insulating units with low-e coatings: energy and comfort
- Spandrel and tinted glass: appearance and solar control
Detailing
- Specify glass type, thickness, coatings, and edge treatment in the glazing schedule
- Size glass for wind load per ASTM E1300 and the code reference in the parent
- Follow the framing manufacturer's glazing instructions for pockets and seals
- Check coating durability and exposed edges, and identify each pane as the code requires
Uses
Specific uses
- Windows, storefronts, and curtain walls
- Glass doors and sidelights
- Skylights and sloped glazing
- Railings, balustrades, and partitions
- Spandrel panels
Pros and cons
Pros
- Daylight and views
- Wide range of strength, safety, and thermal options
- Coatings tune solar gain and reflectance
Cons
- Heat treatment and lamination add cost and lead time
- Spontaneous or thermal breakage needs design attention
- Low-e and tint choices change color and daylight
Manufacturing and cost
Construction
- Float glass is cut, edge-worked, heat-treated, laminated, or sealed into insulating units, then coated and glazed into frames
Main manufacturers and suppliers
Trade association: Fenestration and Glazing Industry Alliance.
Sources
- Buildipedia: 08 80 00 glazing, https://buildipedia.com/component/k2/item/267-08-80-00-glazing
- FGIA: glass standards and guidelines, https://fgiaonline.org/pages/glass-standards-and-guidelines
- Umbrex: glass and glazing lingo, https://umbrex.com/resources/industry-lingo/building-products-construction-materials-lingo/glass-glazing-lingo/
- Viracon: glossary, https://www.viracon.com/?p=109
- Oldcastle BuildingEnvelope: architectural glass product categories, https://obe.com/product-category/architectural-glass/