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.
NIC: 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.
IIC: Impact Insulation Class. This is a laboratory
measurement of the ability of a floor/ceiling assembly to
reduce impact sounds such as footfalls.
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
cove 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 noice 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.
Type of Building
Wood Construction
Concrete Construction
Government Housing
45
45
Entry
48
50
Standard
52
54
High
57
60
Luxury
--
62
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.