Glass Types Overview
The choice of glass significantly impacts the acoustic performance of your secondary glazing. Here's a comparison of the main options:
| Glass Type | Thickness | Rw (dB) | Best For |
|---|---|---|---|
| Float Glass | 4mm | 28-30 | Thermal only |
| Float Glass | 6mm | 31-33 | Light noise reduction |
| Float Glass | 10mm | 34-36 | Moderate noise |
| Laminated Acoustic | 6.4mm | 35-38 | Most applications |
| Laminated Acoustic | 8.8mm | 37-40 | Heavy traffic |
| Laminated Acoustic | 10.8mm | 39-42 | Railways, aircraft |
*Rw = Weighted Sound Reduction Index. Higher is better. These values are for the glass alone; complete system performance depends on air gap and sealing.
Float Glass (Standard)
Standard float glass is the most economical option. It's a single pane of annealed glass made by floating molten glass on molten tin.
Advantages
- • Most cost-effective option
- • Good optical clarity
- • Suitable for thermal improvement
- • Lighter weight
Limitations
- • Lower acoustic performance
- • Less effective for low frequencies
- • Shatters on impact (less safe)
- • No security benefit
When to Choose Float Glass
Float glass is suitable when thermal insulation is your primary goal, or for rooms not affected by significant noise (e.g., rear-facing windows in quiet areas).
Laminated Acoustic Glass
Laminated acoustic glass consists of two or more glass layers bonded with a special acoustic PVB (polyvinyl butyral) interlayer that absorbs sound vibrations.
How It Works
The acoustic interlayer is viscoelastic - it has both viscous and elastic properties. When sound waves hit the glass, the interlayer absorbs and dampens the vibrations, particularly in the critical frequency range of 1000-4000Hz where human hearing is most sensitive.
Glass Composition Options
6.4mm (3/3/0.4)
Most PopularTwo 3mm glass panes with 0.4mm acoustic PVB interlayer
Rw: 35-38 dB | Weight: 16kg/m²
8.8mm (4/4/0.8)
Two 4mm glass panes with 0.8mm acoustic PVB interlayer
Rw: 37-40 dB | Weight: 22kg/m²
10.8mm (5/5/0.8)
Maximum PerformanceTwo 5mm glass panes with 0.8mm acoustic PVB interlayer
Rw: 39-42 dB | Weight: 27kg/m²
Additional Benefits of Laminated Glass
Enhanced Security
The PVB interlayer holds the glass together if broken, making it much harder to break through. Provides a significant deterrent against burglary.
UV Protection
Laminated glass blocks 99% of UV radiation, protecting furniture, artwork, and fabrics from fading and sun damage.
Recommendations by Noise Source
Light Traffic / General Urban Noise
Residential streets, general city background noise
Recommendation: 6mm float glass or 6.4mm laminated
Heavy Traffic / Busy Roads
Main roads, A-roads, urban high streets
Recommendation: 6.4mm or 8.8mm laminated acoustic
Railways / Aircraft / Industrial
Near railway lines, under flight paths, next to factories
Recommendation: 10.8mm laminated acoustic + 150mm gap
Full Specification Summary
| Property | 6mm Float | 6.4mm Lam. | 10.8mm Lam. |
|---|---|---|---|
| Rw (dB) | 31-33 | 35-38 | 39-42 |
| Weight (kg/m²) | 15 | 16 | 27 |
| U-value (W/m²K) | 5.7 | 5.6 | 5.4 |
| Light transmission | 89% | 87% | 84% |
| UV blocking | ~25% | 99% | 99% |
| Safety rating | - | BS EN 12600 | BS EN 12600 |
Related Resources
Noise Reduction Technical Guide
Understanding decibel reduction and how to achieve optimal soundproofing.
Understanding Decibel Reduction
What does dB reduction actually mean? A guide to acoustic performance.
Low Frequency Noise Reduction
Why bass from traffic and trains needs specialised glass solutions.
Railway Noise Reduction
Expert solutions for reducing railway noise in your home.
Get Expert Glass Recommendations
Our acoustic specialists can assess your noise sources and recommend the optimal glass specification.