Which glass, where
In some places a window’s glass is set by a rule rather than by taste. These are five edges a home’s windows can be glazed with, and the guide each one opens.
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Single, annealed
- Where the code asks for safety glassThe places the code asks for safety glazing: doors, the side panels beside them, panels low to the floor, panels that could be mistaken for an opening, and glass in kitchens and bathrooms.
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Laminated
- Where the code asks for safety glassThe places the code asks for safety glazing: doors, the side panels beside them, panels low to the floor, panels that could be mistaken for an opening, and glass in kitchens and bathrooms.
- Laminated or toughened glass: how each one breaksWhat each of the two safety glasses is made of, what the official pages say about how each one breaks, and how the code treats the pair.
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Toughened
- Laminated or toughened glass: how each one breaksWhat each of the two safety glasses is made of, what the official pages say about how each one breaks, and how the code treats the pair.
- Glass in a bushfire-prone areaWhat four states’ official pages say about glass at windows and doors on land mapped as bushfire prone, and how a Bushfire Attack Level is set.
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Double glazed
- What the gap in double glazing does between the panes of glassWhat the sealed gap in a double glazed unit is, what the U value measures, and what a window gains from the second pane and its frame.
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Coated
- Tinted, coated or clear: glass and the sunHow coatings, films and orientation change the solar heat gain coefficient of a window and the light that comes through it.
Glass words
The words the guides use, each in the words of the official page it comes from.
- Grade A safety glazing
- The code’s term for the safety glass it asks for at doors, side panels, low panels, panels that could be mistaken for an opening, and glazing in kitchens and bathrooms. In kitchens, bathrooms, ensuites, spa rooms or the like, shower and bath glass included, where the glass comes lower than 2.0 m above the floor, bath or shower base, it asks for Grade A in framed panels, and for toughened safety glass at least 6 mm thick where any edge is exposed. The NSW Government’s page says AS 1288 counts toughened and laminated safety glass as Grade A.
- Laminated glass
- Standard glass breaks into long shards and small sharp slivers; Your Home says laminated glass has a plastic glazing layer, called an interlayer, adhered permanently between two sheets of that glass.
- Toughened glass
- The NSW Government says it is made by heating glass to a molten state at about 600°C and then chilling it suddenly with compressed air, so its surface contracts and forms a rigid outer layer.
- Double glazing
- Your Home calls it the combination of two or more layers of glass sealed into a frame, with a gap between the layers; the trade name is an insulated glass unit.
- U value
- Your Home: the U value for windows describes the conduction of the whole window, glass and frame together; the lower it is, the greater the window’s resistance to heat flow.
- SHGC
- The solar heat gain coefficient measures how readily heat from direct sunlight flows through a whole window, on a scale from 0 to 1, Your Home says.
- VLT
- Visible light transmittance: the amount of light that passes through the glazing. Your Home notes a low VLT can cut heat gain from the sun, but too low and the room is too dark.
- BAL
- A Bushfire Attack Level, as the NSW Rural Fire Service defines it, measures how severely a building might be exposed to embers, radiant heat and direct contact with flame, in steps of radiant heat counted in kilowatts per square metre.