Acoustic Performance

Noise is one of the things people notice soon after moving into an apartment, and one of the hardest to fix afterwards. On the waterfront there are two kinds to think about: sound between neighbours, and sound from outside.

Between homes. New Zealand Building Code clause G6, Airborne and impact sound, deals with sound passing into household units from abutting occupancies, including neighbouring homes. Its performance requirements set a minimum Sound Transmission Class (STC) of 55 for walls, floors and ceilings between occupancies, and a minimum Impact Insulation Class (IIC) of 55 for floors. STC relates to airborne sound such as voices and music; IIC relates to footfall and dropped objects on the floor above. The clause sets a minimum. It does not promise silence, and many people find code-level separation still lets some sound through.

Hard floors. Timber and tiled floors look good and are easy to clean, but they transmit impact sound more readily than carpet. Some bodies corporate have rules about changing floor finishes for that reason, and an underlay or acoustic layer is often required.

From outside. A building on the harbour hears things that inland buildings do not: wind across balustrades and around corners, halyards slapping on masts in the marina, gulls, events on the promenade, and late-night foot traffic. Glazing, seals and the design of balcony edges all affect how much reaches the inside. Whistling and humming in strong wind usually come from gaps, louvres or edge profiles, and can often be reduced.

Services. Lifts, plant rooms, pumps and waste pipes are common sources of low-level noise in apartment buildings and are best isolated during design.

More on how outdoor spaces behave in wind is under outdoor spaces.