The five things glass can be
Float (annealed). Ordinary glass. Cheap, clear, and breaks into sharp shards. Fine for a high fixed light, wrong anywhere it could be walked into or fall on someone.
Toughened (tempered). Heat-treated to several times the strength, and it granulates rather than shattering. The choice for impact safety in large or low panes. Once broken, it clears the opening completely.
Laminated. Panes bonded to a polymer interlayer. Stays in the frame when broken, blocks almost all UV, and damps sound. See laminated glass windows.
Coated. A microscopically thin metallic layer — low-E or solar-control — that reflects radiant heat while letting visible light through. This is the single most useful thing on a sun-facing Mumbai elevation.
Sealed unit (double or triple glazed). Two or three panes with sealed cavities between them. Usually combines the above: a coated outer pane, a laminated inner one. See double glazed windows.
Matching glass to the room
A bedroom on a main road
Noise is the problem. Asymmetric sealed unit, laminated inner pane. Combine with a casement rather than a slider if you have the swing space, because the frame seal matters as much as the glass.
A west-facing living room
Heat is the problem. Coated sealed unit — the coating is doing most of the work, not the second pane. Add laminated for the UV if there is good flooring or art.
A balcony door or full-height window
Safety is the problem. Laminated or laminated-toughened, because the glass is at body height and a break would leave an opening.
A bathroom or a window facing a neighbour
Privacy is the problem. Frosted, acid-etched or patterned glass, which passes light without a clear view. Obscure glass can be laminated too.
A kitchen window over a counter
Ventilation is the problem more than glass. A top-hung opener with ordinary toughened glass is usually the right answer.
Anything overhead
Laminated, always. No exceptions. See skylight windows.
What glass does not fix
Glass cannot compensate for a frame that does not seal. A high-specification unit in a window whose gaskets have hardened, or whose sash is not pulling tight, will underperform a cheaper unit in a well-sealed frame.
So if an existing window is noisy or draughty, check the seals before assuming you need better glass. Sometimes you do; often you do not.
See glass options for the full range we supply, or tell us the room, the elevation and the complaint, and we will specify it.