Types of Glass for Windows and Doors: A Homeowner's Guide

Walk into a builders' merchant and ask for 'a pane of glass' and you'll get a blank look — there are dozens of types, each suited to a different job. This guide runs through the glass you're most likely to come across in a home, what it's for, and how to know which one you actually need when replacing a window or door pane.

Float glass — the everyday standard

Float glass is ordinary, untreated glass, made by floating molten glass on a bed of liquid tin to give a flat, clear finish. It's the cheapest option and perfectly fine for most upstairs windows that aren't near a door or at low level.

The downside is that when it breaks, it can shatter into large, sharp shards — which is exactly why Building Regulations restrict where it can be used.

Toughened (tempered) safety glass

Toughened glass is heat-treated so it's around four to five times stronger than float glass of the same thickness, and crucially, if it does break, it crumbles into small, relatively blunt granules rather than dangerous shards.

This is the glass required by Part K in doors, side panels next to doors, and windows below 800mm from floor level. If you've had a cracked window repair and the pane was in one of these locations, you'll have had toughened glass fitted as standard.

Laminated glass — for security and noise

Laminated glass is two (or more) layers of glass bonded together with a tough plastic interlayer. If it's struck hard enough to crack, the interlayer holds the pieces in place rather than letting them fall away — which is why it's popular for ground-floor windows, French doors and shopfronts where security matters.

It also does a noticeably better job of cutting down external noise than a single sheet of the same thickness, which is worth knowing if you're near a busy road.

Low-E glass and gas-filled units

Low-emissivity (Low-E) glass has a microscopically thin metallic coating that reflects heat back into the room while still letting light through. It's now the default inner pane in most new double glazed units because of the difference it makes to heat retention — we cover this in detail in our guide to Low-E and argon-filled units.

Obscure and patterned glass

Obscure glass — the textured or frosted glass typically seen in bathrooms and front doors — comes in various patterns and privacy levels. It's covered fully in our separate guide on obscure and privacy glass options, but the short version is that it's usually toughened as well as textured, since it's often within reach of a door or at low level.

Georgian bar and decorative glazing

Georgian bar glass has thin lead or plastic bars either bonded to the surface or sandwiched inside the unit, giving the look of traditional small panes without the draughts of the real thing. It's a popular choice for period-style properties and sash window replacements.

How to know which glass you need

If you're replacing like-for-like — a misted unit, a cracked pane, or a damaged obscure panel — we always match the existing spec so the replacement performs (and looks) the same as the rest of the window.

If you're upgrading, it's worth thinking about location (does it need to be safety glass?), noise, privacy, and heat retention together, since a single unit can combine toughened, laminated, Low-E and obscure properties in one build-up.

• Near a door or below 800mm — must be toughened or laminated safety glass
• Bathroom, en-suite or street-facing ground floor — consider obscure glass
• Facing a busy road — laminated glass cuts noise noticeably
• Any room you want warmer in winter — Low-E glass and argon fill

Call Mark on 07535 916982 or request a callback.