Triple glazing, acoustic glass and traffic noise
For noise, acoustic laminate usually beats triple glazing per pound; for the best possible figure, triple wins. Triple reaches 44 dB, a 6.8 mm acoustic laminate double unit reaches 41 dB in a casement. On a 70 dB kerbside street that is about 26 dB inside against 29 dB — a difference you can hear but not a different room.
Which applies to you
- A main road, front rooms
Triple glazing at 44 dB, and check the sash weight. Triple is heavier, so aluminium at 130 kg per sash takes sizes uPVC at 80 kg will not.
- Traffic noise on a budget
6.8 mm acoustic laminate in a standard double unit. 41 dB, no weight problem, and it is also the laminated pane that improves ground-floor security.
- A sash window on a busy street
Accept 39 dB. A sash seals with brushes, not compression, so the glass is not the limiting factor: the meeting rail is. Secondary glazing is the honest answer if you need more.
- Aircraft or low-frequency noise
Asymmetric glazing, different pane thicknesses either side of the cavity. Two panes of the same thickness resonate together; that is what makes a symmetric unit underperform its rating.
The figures behind it
- Triple glazed
- 44 dB, Ug 0.6
- Acoustic laminate double
- 41 dB casement, 39 dB sash
- Standard 4/20/4
- 32 dB, Ug 1.1
- Maximum sash weight
- Aluminium 130 kg · uPVC 80 kg
- Typical kerbside
- About 70 dB
