Glass Types Explained
A plain-English guide to the glass types we use in balustrades, staircases, and partitions — so you can choose with confidence.
Why Glass Type Matters in Balustrades
All glass used in balustrades, Juliet balconies, and guarding applications must be safety glass. This is a legal requirement under Approved Document N of the Building Regulations and BS 6262. We only ever supply toughened or laminated glass in safety barrier applications — no standard float glass, ever.
Beyond standard clear glass, we can supply grey tinted, satin, reeded, coloured interlayer, and specialist laminated options — all in toughened or laminated safety glass specification. The guide below explains the core glass types and thicknesses used across our systems.
Toughened (Tempered) Glass
Toughened glass is produced by heating standard float glass to around 620°C and then rapidly cooling it. This thermal process puts the outer surfaces into compression and the inner core into tension, making the finished pane approximately four times stronger than untreated glass of the same thickness.
If toughened glass is broken — which takes a significant impact — it shatters into small, rounded fragments rather than long, sharp shards. This characteristic is what qualifies it as safety glass.
- Approx. 4× stronger than standard float glass
- Breaks into small blunt fragments — no sharp shards
- Compliant with BS EN 12150
- Available in 8mm, 10mm, 12mm, and 15mm thicknesses
- Cost-effective choice for most residential installations
Toughened glass is used in framed post & rail systems, semi-frameless systems, and frameless channel systems where laminated is not a regulatory requirement. Because it is thermally processed as a finished pane, holes, notches, and cut-outs must be specified before toughening — they cannot be added afterwards.
Laminated Glass
Laminated glass is made from two or more glass plies permanently bonded together with an EVA (ethylene-vinyl acetate) interlayer. EVA offers superior clarity, moisture resistance, and long-term adhesion compared to PVB — and is the interlayer we specify across all our laminated glass. If a laminated panel is broken, the interlayer holds the fragments in place — the glass cracks but stays within the frame or channel rather than falling away.
This retained-glass-on-break characteristic is essential in elevated applications. If a toughened-only panel were to fail at height, the fragments would drop. Laminated glass stays put. This is why it is mandatory for Juliet balconies, exposed elevated balconies, and pool fencing.
- Glass stays in fixings if broken — no falling fragments
- Compliant with BS EN 14449
- Required on all Juliet balconies and elevated external use
- Required for pool fencing applications
- Standard thicknesses: 13.5mm (2×6.4mm), 17.5mm (2×8mm), 21.5mm (2×10mm)
Laminated glass is slightly more expensive than toughened glass of comparable thickness and is also slightly heavier. For most residential elevated applications we specify 17.5mm laminated as a minimum.
Low Iron (Extra-Clear / Optiwhite) Glass
Standard clear glass contains a small amount of iron oxide in its composition. This gives it a faint green tint, most visible when you look at the edge of a panel or view it against a white background. For most applications this tint is barely noticeable, but in premium installations — particularly against white or light-coloured walls — it can be aesthetically undesirable.
Low iron glass (sold under trade names such as Optiwhite, Starphire, and Diamant) has the iron content significantly reduced, resulting in a truly colourless, crystal-clear panel with no green cast whatsoever. Light transmission is marginally higher than standard glass.
- No green tint — truly colourless appearance
- Highly recommended for frameless frameless installations on light-coloured elevations
- Ideal for indoor glass partitions and wine rooms where clarity is paramount
- Marginally higher light transmission than standard clear
- More expensive than standard toughened or laminated glass
Low iron glass is available in both toughened and laminated specifications. If colour accuracy matters to your project, ask us about upgrading to low iron at the quotation stage.
Recommended Glass Thickness by System
The table below shows our standard glass specifications for each balustrade system. Actual specification is always confirmed during the survey, as span, loading, exposure, and height all influence the final selection.
| System / Application | Recommended Thickness | Glass Type |
|---|---|---|
| Post & rail framed (indoor) | 10mm | Toughened |
| Post & rail framed (outdoor) | 10mm | Toughened |
| Semi-frameless | 10mm or 11.5mm | Toughened or Laminated |
| Frameless channel (residential) | 17.5mm | Laminated |
| Frameless channel (elevated / exposed) | 17.5mm | Laminated (minimum) |
| Frameless spigot | 17.5mm or 21.5mm | Laminated |
| Juliet balcony | 17.5mm or 21.5mm | Laminated |
| Pool fencing | 17.5mm | Laminated (minimum) |
| Staircase panels (grooved channel) | 8–10mm | Toughened |
| Staircase panels (clamped) | 10mm | Toughened |
More Than Just Clear Glass
While clear toughened and laminated glass is the most common choice, we can supply a range of glass types and finishes to suit your project. Options include:
- Clear toughened or laminated — the standard for most installations
- Grey tinted — a subtle tint that can complement darker frames and contemporary schemes
- Satin / acid-etched — a frosted finish for privacy without blocking light
- Reeded — textured patterned glass for decorative applications
- Coloured interlayer — laminated glass with a coloured EVA interlayer for a bold, bespoke look
- Specialist interlayers — including acoustic, UV-filtering, and privacy interlayers on request
- Low iron (Optiwhite) — crystal clear with no green tint, ideal for premium frameless installations
If you have a specific requirement, mention it at the quotation stage and we will advise on what is achievable within your system type and budget.
BS EN 12150 — Toughened Glass
The British and European Standard governing thermally toughened soda lime silicate safety glass. Sets requirements for dimensional tolerances, fragmentation behaviour, and bow and warp limits. All toughened glass we supply meets this standard.
BS EN 14449 — Laminated Glass
The British and European Standard covering laminated safety glass and laminated glass. Specifies the test methods for interlayer adhesion, resistance to humidity, and retained glass performance after breakage. All laminated glass we supply meets this standard.
Acoustic Interlayer — How It Works and When You Need It
Standard laminated glass uses an EVA interlayer primarily for safety — to hold the glass together if it breaks. Acoustic laminated glass uses a specialist interlayer, typically a visco-elastic PVB compound, that is specifically engineered to absorb and dampen sound energy as it passes through the glass. The interlayer converts acoustic vibration into a small amount of heat rather than allowing it to pass through as sound.
How Standard vs Acoustic Interlayer Compare
Standard laminated glass (EVA interlayer) achieves a sound reduction index (Rw) of approximately 35–38 dB for a 6.4mm unit. Acoustic laminated glass using a specialist interlayer can achieve Rw 38–42 dB or higher at the same thickness — the difference is entirely in the interlayer composition, not the glass thickness. For double-glazed partition units using acoustic glass, Rw values of 44–50 dB are achievable.
Where Acoustic Glass Is Used
Acoustic interlayer glass is most commonly specified in glass partitions — meeting rooms, private offices, HR suites, and any space where speech privacy matters. It is also used in external glazing near roads or railways where noise ingress is a concern, and in internal screens between areas with significantly different noise levels, such as server rooms or production areas adjoining offices.
Glass Alone Is Not Enough
Acoustic glass improves the sound reduction of the glazed panel itself — but the weakest point in any glass partition or screen is almost always the door and its seals, not the glass. A high-specification acoustic panel fitted next to a poorly sealed door will perform no better than standard glass. Acoustic performance is a system result, not a glass specification in isolation.
Thickness and Unit Construction
Common acoustic laminated units: 6.4mm (3mm + 0.4mm interlayer + 3mm), 6.8mm, and 8.8mm. In double-glazed partition units, an acoustic laminated inner pane combined with an air or argon cavity gives the best overall performance. The cavity width and any asymmetry in pane thickness (e.g. 6mm outer / 4mm inner) further reduce coincidence effects — the frequency at which glass becomes acoustically transparent.
Acoustic Glass in Partitions — The Door Is the Critical Detail
When acoustic laminated glass is specified in a glass partition system, the door is where most of the acoustic performance is won or lost. We use two approaches depending on the system and performance requirement:
- Framed door with perimeter acoustic seals — an aluminium-framed door leaf with compression seals fitted to all four sides of the door frame. When the door closes, the seals compress against the frame and glass, blocking the air path that sound travels through. This is the standard approach in aluminium-framed partition systems and gives the best acoustic result.
- Flexible perimeter brush and blade seals — where a rigid compression seal isn't suited to the door configuration, we use high-density brush or flexible blade seals fitted to the door frame perimeter. These maintain continuous contact with the door leaf as it closes, blocking the air gaps through which sound travels without requiring the precise mechanical engagement of a compression seal. A practical and effective solution for frameless or pivot door configurations where standard framed seals cannot be fitted.
For meeting rooms and private offices, we always recommend a framed door with perimeter compression seals as the default — it delivers the most consistent acoustic result. Brush and blade seals are well suited to frameless and pivot door configurations where the frame geometry makes compression seals impractical, and perform well across a broad frequency range when correctly specified.
Ready to Discuss Your Glass Balustrade?
We will advise on the correct glass type and thickness for your application, provide a detailed specification, and give you a fast, no-obligation quotation.