When we choose to live in a condominium whose walls, ceilings, and floors are directly adjacent to our neighbors, a certain amount of noise is going to be part of the bargain. When deciding to enter into this bargain, how do we know how much noise is acceptable, and when is that noise too much noise?
Most condominium Declarations have a boilerplate provision that states something like this:
No noxious or offensive activity shall be carried on in any unit or common or limited common areas, nor shall anything be done therein which may be or become an annoyance or nuisance to other unit owners, or which would be in violation of any laws.
This language is very general and very vague regarding the specifics of sound transmission.
Acoustical engineers measure sound to calculate a number of interrelated metrics to assist owners in complying with the rules for sound transmission in their condominiums. The following single-number ratings calculated are often used:
AIIC (Apparent Impact Insulation Class) – Historically, the metric used for unfinished and unfurnished spaces using the same normalization analysis as laboratory tests.
ISR (Impact Sound Rating) – The non-normalized single-number rating most closely approximates the perceived footfall noise in the receiving room.
NISR (Normalized Impact Sound Rating) – ISR results normalized to a finished and furnished multifamily dwelling space, approximating an average living room or bedroom with furnishings.
HIR (High-Frequency Impact Rating) – This metric describes the acoustical performance of the flooring and underlayment independent of the building construction compared to the ISR and NISR metrics.
LIR (Low-Frequency Impact Rating) – This metric describes the acoustical performance of the fundamental properties of the floor-ceiling assembly commonly described as a “thud” or “thump” associated with movement upstairs. The frequency range associated with the metric is below the range noted in the ISR and NISR metrics.[1]
Additional reference is made to the Sound Transmission provisions in Section 1206 and 1207 of the International Building Code (IBC), the International Code Council (ICC-G2) Guideline on Acoustics, and the U.S. Department of Housing and Urban Development in the Guide to Airborne, Impact, and Structure Borne Noise Control in Multifamily Dwellings. The minimum acceptable sound measurements for wood-framed multi-family building in the United States is an IBC measurement of NISR 45, an ICC Grade II Average performance of NISR 52, and the HUD Grade II, which is an average of an AIIC/NISR 52.
To prevent unwanted sound transmission when condominium unit owners replace carpeting with hard wood flooring or luxury vinyl hard surface flooring, it is wise to require submission of samples of the materials that are to be installed and to have an acoustical engineer test the samples and units in which the installation is to be made prior to authorizing the installation. This will keep the tapdancing of your neighbors at a tolerable level.
[1] Descriptions used are from Tenor Engineering Group materials.
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