Secondary Glazing for Railway & Tube Noise

Wheel-rail interaction produces a broadband rumble with substantial energy at 50-160Hz, which passes through lightweight construction almost unimpeded. On curved sections — common on the London Overground and District Line surface track — flange contact adds a 2-5kHz squeal that is far easier to block but psychologically very intrusive.

Rail is the application where we push cavity depth hardest — 200mm where the reveal allows. Combined with 10.8mm acoustic laminate, that resonates the mass-spring-mass system well below the dominant rumble band, so low-frequency energy is attenuated rather than transmitted.

Where reveal depth is limited, we compensate with heavier glass and, occasionally, an asymmetric pairing of 10.8mm secondary against the existing 4mm primary to avoid coincident resonance.

Very close to a track — within roughly 15 metres, or above a tunnel — some energy arrives through the ground rather than the air. Secondary glazing cannot address structure-borne vibration. Our survey identifies whether your problem is airborne, structural, or both, so expectations are set honestly before you order.

Living beside a surface line, a Tube cutting or an Overground viaduct is a different acoustic problem from living on a main road. Rail noise is intermittent and impulsive: long quiet periods broken by a 10-20 second event with a fast onset, wheel-flat clatter and, on older stock, brake squeal reaching well into the high frequencies. It is the suddenness that wakes people, not the average level, which is why average-based specifications underperform on rail corridors.

The specification therefore aims at peak reduction rather than a comfortable average. That means the heaviest laminate the frame will carry, the deepest achievable cavity, and absolute discipline on sealing — an impulsive event will find a 2mm gap that steady traffic noise would mask.

Secondary glazing treats airborne sound. Where a Tube line runs under or immediately beside the building, part of what you feel is structure-borne vibration transmitted through the ground and the building frame, and glazing cannot remove that — it arrives through the floor and the walls, not the window.

We are explicit about this at survey because it sets expectations correctly. In most London rail-adjacent properties the airborne component dominates and residents report the improvement they hoped for. Where vibration is significant we say so and, if needed, refer the structural element to a specialist rather than over-promising on glass.

The default for a bedroom facing a surface line is 10.8mm acoustic laminate, a 100-150mm cavity and a fixed or lift-out panel where the window is not a daily ventilation route, because a panel with no meeting stile seals hardest. In suitable configurations that reaches up to 54dB reduction; the practical outcome most residents describe is that trains become a soft presence rather than an event that interrupts sleep.

These build-ups are delivered by our acoustic glazing London service, and we recommend an overnight or peak-period survey rather than a daytime one so the measurement captures the actual event levels.