HARD SURFACE FLOORS NOISE ABATEMENT

Hi all,
In another thread, there is an interesting string of statements as regards the requirement for noise reducing underlayment in Florida. The following may prove instructive:
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Sound damping underlayment, a simple matter of the Florida Building Code. If that is not good enough, simply build it into your Bylaws.


REF: The following is extracted from the Florida Building Code:

REF: http://www.floridabuilding.org/BCISold/bc/default.asp


SECTION 1207 SOUND TRANSMISSION

1207.1 Scope. This section shall apply to common interior walls, partitions and floor/ceiling assemblies between adjacent dwelling units or between dwelling units and adjacent public areas such as halls, corridors, stairs or service areas.

1207.2 Air-borne sound. Walls, partitions and floor/ceiling assemblies separating dwelling units from each other or from public or service areas shall have a sound transmission class (STC) of not less than 50 (45 if field tested) for air-borne noise when tested in accordance with ASTM E 90. Penetrations or openings in construction assemblies for piping; electrical devices; recessed cabinets; bathtubs; soffits; or heating, ventilating or exhaust ducts shall be sealed, lined, insulated or otherwise treated to maintain the required ratings. This requirement shall not apply to dwelling unit entrance doors; however, such doors shall be tight fitting to the frame and sill.

1207.3 Structure-borne sound. Floor/ceiling assemblies between dwelling units or between a dwelling unit and a public or service area within the structure shall have an impact insulation class (IIC) rating of not less than 50 (45 if field tested) when tested in accordance with ASTM E 492.
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For those who desire a bit of Technical explanation of the ratings noted in the Code, the following is provided.
REF: http://continuingeducation.construction.com/article.php?L=111&C=409&P=2

There are two types of ratings used for sound control: Sound Transmission Class (STC), which measures airborne sound, such as speaking, music, etc.; and Impact Insulation Class (IIC), which measures impact sound, such as that from people walking, moving chairs, dropping objects and the like. The current International Building Code requires a minimum IIC rating of 50 for both, and 45 if field-tested.


Sound Transmission Class (STC). Sound transmission class is a number rating of how well a building partition—wall, ceiling, floor, door—blocks airborne sound. For interior walls, STC values are derived from ASTM E 90, “Standard Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions.” ASTM E 90 measures a partition’s ability to reduce the transmission of airborne sound at 16 frequencies between 125 Hz and 4,000 Hz, the frequency range of speech.


Following are some generally accepted facts about STC ratings.


• Loud speech can be understood fairly well through an STC 30 wall but should not be audible through an STC 60 wall.


• An STC of 50 is a common building standard and blocks approximately 50 dB from transmitting through the partition. But STC 50 is not enough to stop loud music from a neighbor’s stereo which can exceed 100 dB. Although an STC 50-rated assembly will satisfy the building code requirement, residents may still be aware of, if not understand, loud speech from an adjacent apartment.


• STC 55 or STC 60 should be specified in sensitive areas where sound transmission is a concern. At STC 55, extremely loud sounds such as loud music from a neighbor’s stereo will heard so faintly that the vast majority of the population will not be disturbed.


• Luxury accommodations are considered to require more stringent design goals of as much as STC 60. At STC 60 and above, considered the ultimate in soundproofing, most sounds will not be audible. Walls rated STC 65 and above are generally reserved for ultra-luxury hotels and multi-family structures or purpose-built home theaters.


The only thing is, there are inherent weaknesses in the STC rating system. STC ratings are heavily weighted toward speech frequencies, and are less accurate for a partition’s ability to block low frequency noise, such as the bass in music, mechanical equipment noise, transportation noise or other sound with low-frequency energy below 125 Hz. STC ratings also represent testing in optimum laboratory conditions, and are rarely achieved in real world situations. The difference between Laboratory and field STC ratings stem from a structure’s flanking paths—the small holes, roof voids, even windows and doors which decrease a wall’s acoustic insulation. Consequently, the Field Sound Transmission Class or ''FSTC'' can be five to ten points lower than the laboratory STC. Yet regardless of what STC is selected, it is critical to control and seal all air-gaps and penetrations. Failure to do so can degrade the sound blocking capability of an assembly.


Impact Isolation Class (IIC).As STC ratings refer to airborne noise, IIC ratings target structure borne noise. The term IIC refers to a measure of isolation effectiveness of building structures from impact noises such as slammed doors, footsteps, dropped articles, etc. in a multi-family building. Impact noises can be transmitted through walls, floors, and ceilings throughout a building and re-radiated at distant locations. The higher the IIC rating, the better the isolation. IIC is measured and stated in accordance with ASTM Standard numbers C634 and E989 and tested via the methodology of ASTM Test Method E492. Generally speaking, IIC values are not heavily influenced by the extent of solid mass in the structure, but are usually dependent on the presence of some sort of resilient material in the assembly that can isolate and absorb the energy created by impacts.


Hopefully this will put an end to the questions and controversy on this issue.


Dave Israel