Guidelines

Flooring/Ceiling Sound Isolation)

The purpose of this information is to provide Homeowner’s Associations information relating to the acoustical performance of floor/ceiling assemblies. This should facilitate the HOA in establishing guidelines to meet the needs of their building. This information is for guideline purposes only. Each building is unique. The building should contract with appropriate legal counsel and design professionals prior to incorporation of binding requirements within CC&Rs.

ACOUSTICAL TERMS

In multi-family dwellings, acoustical consultants use the following terminology to define the performance of a floor/ceiling assembly.

• STC: Sound Transmission Class. This is a laboratory measurement of the ability of a specific construction assembly (such as a partition, window, door, etc.) to reduce airborne sounds including voice, television and alarm clocks.
• Noise Isolation Class. This is an over-all measure of the sound isolation between units in a multi-family dwelling. This quantity is a field measurement of the ability of a partition, floor/ceiling assembly, etc., to mitigate airborne sounds including voice, television and alarm clocks.
• Impact Insulation Class. This is a laboratory measurement of the ability of a floor/ceiling assembly to reduce impact sounds such as footfalls. Get more information regarding how IIC ratings are calculated.
• FIIC: Field Impact Insulation Class. This a field measurement done in situ after a floor installation is completed.

The higher the value of any of the quantities above, the greater the airborne or impact isolation provided by the assembly.

REQUIREMENTS

Building Code requirements that include Sound Insulation Standards normally require that:

• Airborne Sound Insulation is not less than STC 50 if laboratory tested, or not less than NIC 45 if field tested.
• Impact Insulation is not less than IIC 50 if laboratory tested, or not less than FIIC 45 if field tested.

Buildings are not soundproof. Sounds from adjacent units or other building activity are almost always audible even when the building code requirements are met.

BUILDING CONSTRUCTION

Building construction floor/ceiling assemblies vary and can affect the types of sound heard from unit to unit.

• CONCRETE: No Suspended Ceiling. A concrete slab is the only vertical separation between dwellings.Impact sound transmission is normally the major concern. Impact noise from heels or movement of chairs on floor often audible below.
• Suspended Ceiling. Concrete slab with a gypsum board ceiling hung below at some distance. Impact noise transmission is normally the major concern.
• WOOD: Typical construction includes joists, plywood, lightweight concrete, sound insulation, drywall and resilient channels. Higher potential for complaints because of lightweight nature of floor/ceiling assembly. Thudding from footfall almost always present. Impact noise transmission is normally the major concern.

FLOOR SURFACES

In floor/ceiling assemblies, typical finish flooring is carpet or hard surface. The IC/FIIC code requirements are almost always met with carpet. If a carpet is going to be replaced with hard surface, there will be significantly greater impact noice transmission to the unit below.

Role of Sound Rated Flooring Utilizing Resilient Underlayments

In any of the buildings described, a sound rated flooring system, when properly installed, will significantly improve the IIC/FIIC when compared with a non-rated hard surface floor system. The sound rated flooring products do not have a significant effect on the STC/NIC of the floor/ceiling assembly.

What Can An HOA Do?

The CC&Rs of the building allow the HOA to maintain a level of airborne and impact sound isolation appropriate for the building design. We address the flooring issue below.

• Establish a FIIC requirement for hard surface flooring. Guidelines are provided in the table below. Many factors should be considered in establishing your building requirement and the values provided below are given for guidance only.

The requirement that is set will, most likely, require the use of a resilient underlayment within a sound rated assembly. Given the basic building construction, the achievable FIIC may be limited. The HOA should employ a qualified acoustical consultant to ensure a proper, achievable requirement is established.

• Utilize an attorney to draft a format for the addition to the CC&Rs.
• Require that all changes to flooring be reviewed by the HOA and meet the performance requirements. Require submission of a lab report from a nationally recognized independent acoustical testing laboratory having a similar construction to the building. Require a drawing showing where the hard surface flooring will be installed.
• If a complaint occurs after installation, a FIIC test should be performed by an accredited acoustical laboratory approved by the HOA. The complaint should post a bond for said testing. If the test meets the building requirement, costs shall be chargeable to complainant. If the test fails, cost shall be borne by the owner of the hard surface flooring material.