How Much Sound Insulation Do I Need?

Information on Insulating for Sound

The current National Building Code of Canada (NBC) prescribes sound insulation levels that are orders of magnitude lower than those found in European building codes. This is in large part because European building practices are based on “mass-walls”, which absorb noise much better than our light frame constructions. The current NBC has traditionally set minimum noise levels which are simply descriptive of what open light frame constructions provide – compliance with these code requirements do not require any significant noise control measures to be taken.

The 2015 National Building Code of Canada (NBCC) has broken fresh ground here. A new minimum performance requirement of ASTC 47 has been introduced, which includes control of both direct and indirect (flanking transmission) sound transmission paths. So the builders and renovators have a “how-to” guide to provide better sound insulation.

Ask your prospective home builder or renovator to give you options.

Some words of caution:

  • Codes traditionally set a minimum acoustic performance only on noise energy transmitted through a given assembly (addressing only the direct transmission path), called Sound Transmission Class (STC). The Canadian 2015 National Building Code has introduced Apparent Sound Transmission Class (or ASTC), which includes controlling both the direct and indirect transmission paths (flanking) the noise paths around the given assembly. The ASTC is the key measure for improvement. A minimum ASTC 47 is required by Code but an ASTC 55 and above is recommended for enhanced acoustic performance.
  • Floor and ceiling assemblies are also rated for impact sound resistance. Impact sound is structure-borne sound transmitted when one body strikes another, such as in the case of footsteps and falling objects. A single number, the impact insulation class (IIC), is used to describe impact sound performance. As with STCs and ASTCs, a higher number indicates better performance. A minimum IIC of 50 is recommended.