Cutting traffic and aircraft noise with better glazing
What the acoustic ratings mean, why two panes of different thickness beat one thick pane, and why the gaps around the frame often matter more than the glass.
- Acoustic laminated glass and airtight frames do most of the work.
- Different pane thicknesses with a decent cavity beat simply thicker glass.
- Trickle vents need to be acoustic, or they undo the glazing they sit in.
Sound is easier to keep out than most people expect, provided you work on the whole assembly rather than just the glass. Traffic, aircraft and neighbours reach a room through the glazing, but also through every gap around it.
What the ratings mean
Rw is the single figure acoustic rating of a glazing unit. For traffic noise, look for Rw plus Ctr, which accounts for the low frequencies of engines and tyres and is usually several decibels lower than Rw on its own. A product sold on Rw alone can disappoint on a main road.
Why two panes of different thickness
Sound passes less easily through two panes of different thicknesses with a decent air gap between them, because the two sheets resonate at different frequencies. A typical build-up is 6.8mm laminated glass on the outer pane, 4mm or 6mm on the inner, and a 12mm to 16mm cavity.
Laminated glass with a dedicated acoustic interlayer adds damping that plain glass of the same thickness cannot match.
The gaps matter most
A 5mm gap around a door lets in more noise than the glass keeps out. Check the gaskets, the threshold sealing, the joint at the reveal and, above all, the trickle vent, which is a deliberate hole in the wall.
Where ventilation is required but noise is a problem, acoustic trickle vents or a mechanical ventilation system with heat recovery solve both at once.
What to expect
A well specified acoustic door or window takes the worst edge off a busy road and makes a bedroom usable. Absolute silence is not a realistic target on an urban site, and no glazing system will deliver it.
Written by the Minimal Frame Projects UK team. If you would like advice on a specific opening, send us the dimensions and a few photographs and we will come back with a specification.
