Technical guide
Acoustic glazing and what it costs
A standard 4-16-4 double glazed unit gives roughly 30dB of sound reduction. An asymmetric acoustic laminate build-up reaches 38–42dB, and secondary glazing with a wide air gap can exceed 45dB.
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Why asymmetric works
Two panes of the same thickness resonate together at the same frequency and let that band through. Different thicknesses — say 6.8mm laminate against 4mm — move the resonance and close the gap.
The interlayer matters
An acoustic PVB interlayer damps vibration within the laminate itself. It typically adds 3–5dB over a standard laminate of the same thickness for a modest cost increase.
Air gap beats glass thickness
Beyond a point, adding glass gives diminishing returns while a wider cavity keeps improving low-frequency performance. This is why secondary glazing 100–200mm inboard outperforms almost any sealed unit.
Decibels are logarithmic
A 10dB improvement is perceived as roughly halving the loudness. Moving from 30dB to 40dB is a very large practical change; 40dB to 43dB is barely noticeable.
Seals decide the outcome
A 45dB unit in a frame with worn gaskets performs like a 32dB one. Perimeter sealing and frame condition are as important as the glass specification.
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Where this applies
Glass partitions
A glass partition is a non-loadbearing internal screen that divides a floor plate without blocking light.
Commercial aluminium windows and doors
Commercial aluminium windows and doors are thermally broken framed units built for heavy use — far higher cycle ratings, wider spans and stronger hardware than residential equivalents, with a polyamide break separating inner and outer frame.
Double glazed unit replacement
A double glazed unit, or IGU, is two panes bonded to a spacer bar with a sealed cavity between them.
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