Acoustic Glazing in Wellington

Two situations drive most of this work in Wellington. The first is the airport flight path, which runs over Miramar, Strathmore Park, Rongotai and Lyall Bay. The second is arterial road frontage, which affects a lot of Newtown, Kilbirnie, Adelaide Road and the Hutt Road corridor. In both cases owners often buy standard double glazing expecting a big drop in noise and end up disappointed, because a plain unit was never designed for it.

Why a standard double glazed unit disappoints on noise

A standard unit uses two panes of the same thickness with a narrow air gap. Two identical panes resonate at the same frequency, so sound passes through both of them fairly happily. The gain over single glazing is real but modest.

Acoustic units break that symmetry. A 6.38mm laminated pane on the outside and a 4mm pane on the inside resonate at different frequencies, and the interlayer in the laminate damps vibration instead of transmitting it.

What makes the difference

Laminated glass first, because the plastic interlayer is the single biggest contributor. Then unequal glass thicknesses. Then a wider cavity, which helps low frequency noise, and that is the range aircraft and heavy traffic sit in.

Seals matter as much as glass. A perfect acoustic unit in a sash with perished weather seals leaks noise straight around the edge, so we re rubber at the same time.

Realistic expectations

Acoustic glazing reduces noise. It does not eliminate it, and it does nothing about sound coming through walls, roofs or under doors. In a lightweight timber villa the glass is often no longer the weakest link once it has been upgraded.

We will tell you what the glass can and cannot do before you spend the money, and where the remaining noise is likely to be coming from.

What actually reduces noise

Mass, damping and asymmetry

Three things reduce sound through glass. Mass, which means thicker glass. Damping, which is what the plastic interlayer in laminated glass provides. And asymmetry, meaning two panes of different thickness so they do not resonate together.

A standard double glazed unit has none of the three: two equal panes with a narrow air gap. That is why people who buy it expecting quiet are disappointed.

The weakest link decides the result

A perfect acoustic unit in a sash with perished weather seals leaks sound straight around the edge, and no amount of glass fixes that. Neither does it help with sound coming through walls, ceilings, doors or an uninsulated floor.

We re rubber at the same time as glazing on any noise job, and we tell you where the remaining noise will be coming from so you can decide whether it is worth going further.

Acoustic Glazing at a glance

Typical build

6.38mm laminated outer, wider cavity, 4mm inner

Key factor

Laminated interlayer, then unequal glass thicknesses

Low frequency

Wider cavity helps aircraft and heavy traffic noise

Seals

Weather seals replaced at the same time or the gain is lost

Suits

Flight path suburbs, arterial road frontages, bedrooms

Frames

Fits existing frames in most retrofit situations