Acoustics

The New Zealand Building Code ‘G6’ clause aims to protect spaces from excessive noise through two separate performance requirements; A Sound transmission class (STC) of 55 and an Impact Insulation Class (IIC) of 55 or a FIIC rating of 50.  The FIIC is the same as IIC but undertaken in a field situation (F) i.e. an apartment.

​The simplest option to meet the building code is to specify carpet tile, our full carpet tile range typically has enough acoustic resistance to pass both the STC and FIIC test on its own.  For total peace of mind, in multi-storey buildings we recommend specifying Interface Carpet Tiles with CushionBacRE backing as this meets the criteria for an automatic pass under the building code. No specification for the weight of the carpet tile or underlay is given. However, as a rule the more fluff on top, the better the STC rating and the thicker the backing, the better the FIIC rating.

​For both performance requirements there are Acceptable Solutions listed in the G6/AS1, showing diagrams of suitable wall, floor and ceiling assemblies to meet the STC or IIC55 requirements.

Alternative products are usually harder – tiles, wood or laminate, but may also be resilient products like vinyl and Luxury Vinyl Tile (LVT).  All will likely require some form of underlay or be an ‘acoustic’ or cushion version, this is often built into vinyl and LVT products. Foam or rubber underlays are the most common, in varying thicknesses.

Any product test results are an indication only, a field test with the subfloor and ceiling assembly is needed to ensure the IIC value of 55 is reached.