The use of ceramic tile in commercial and residential construction continues to grow, despite the recent economic slowdown. There are many reasons for this trend:
- facturing improvements have kept the price affordable.
- Design capability and color selection is limitless.
- Long life cycle and durability add value to the home.
- Trends in construction (expanding kitchens, baths and other areas where ceramic tile is desired).
- Larger formats and fewer grout lines.
- Low required maintenance.
- Improvements in installation materials performance.
Think about it for a minute: Where would our industry be if backerboard had never been invented? Or epoxy grout that is easy to work with? Self-leveling patches and underlayments? Innovations in tools? You get the picture.
One of the most important technological improvements over the years has to do with controlling the transmission of sound. The explosion of high-rise commercial and residential multi-family construction in coastal and urban areas, coupled with an increasing trend to revitalize city development by building projects to spur downtown investment and growth, presents significant opportunity to our trade. The problem lies with controlling noise.
It is quite common now to see products being advertised as ideal for providing sound abatement to a structure. Before choosing a system or jumping into a project you may lack sufficient knowledge in, I suggest doing some research on it. The problem has some complexities that beg simplification.
Sound Rated Floors in TCA HandbookTo better educate yourself, consider purchasing the TCA Handbook for the installation of ceramic tile (www.tileusa.com). Located on pages 77 and 78 of the 2007 edition, the Handbook explains what sound control is as it relates to the tile industry. The following are some highlights of the information you can find in this valuable reference tool. It is my hope this will spur you to research the situation in more detail.
STC and IICThere are two different sets of rating systems used to determine sound transmission. STC refers to Sound Transmission Class and would include measuring sound as it travels through building elements such as wall or floor systems. Voices, radio and television are examples of the type of sound being measured in an STC rating system.
IIC stands for Impact Insulation Class and refers to the statistical measurement standards used to quantify the transmission of impact sound energy through a floor/ceiling assembly system. Examples of this type of sound would be foot traffic, such as high heels on a floor, furniture moving, glass breaking, and more.
In most multi-family construction, there are minimum STC and IIC values that the floor/ceiling assemblies must achieve in order to meet building code standards. The most common building code standards used are the Uniform Building Code (ICC/BOCA U.B.C.) and the International Building Code (IBC). It is the responsibility of the project engineer or architect to identify the applicable code standards on a project.
A word of caution to all industry professionals is that some products that are promoted for sound control may meet the code requirements on a project, but not necessarily meet the requirements set forth by the building developer or condominium owners association. Therefore, it is important to consult this requirement in addition to understanding the local codes.
ChallengesNumerous materials comprise a system to be used for sound control. Each product is only one component of the entire assembly. The desired sound rating can be affected if any of these components is absent. Ideally, testing the assembly should take place in both the field and an accredited test laboratory. Products that promote ratings from the field only should be treated with caution. Tests should be performed both before and after installation.
Many materials that are promoted for sound control in hard surface flooring may not be suitable for direct bond tile and stone installations, as they are too compressible and do not provide proper structural support for these installations. In many cases, it is necessary to use additional reinforcing materials, such as mortar beds, backer boards, epoxy mortars and grouts and other methods to provide a structurally sound installation.
It is recommended that all products/systems to be used for sound control be subjected to ASTM C627, commonly referred to as the Robinson Floor Test, and that a minimum Residential Rating be met.
Concrete and Wood SubfloorsConcrete slabs come in a variety of thicknesses and compositions. The most commonly cited systems are either 6” or 8” concrete slabs with or without a suspended ceiling assembly. Test results vary greatly when comparing field and laboratory tests, with the field tests yielding a higher range of values than lab results. Thus, note the importance of utilizing both procedures to achieve a high rate of success.
If a suspended ceiling assembly is not specified, the most effective method to improve an Impact Insulation rating is to install a “floating floor” system. This can be done by utilizing a layer of some type of acoustically rated resilient material, followed by a layer of lightweight concrete, mortar bed, or gypsum concrete (usually 3/4” or more, depending on the material), onto which the tile or stone is to be installed.
Wood frame construction will normally have a gypsum wallboard ceiling assembly. If resilient metal channels supporting the gypsum wallboard are installed with sound-absorbing batts in the cavity, the IIC rating on a single layer subfloor will be approximately 45. A ceramic tile installation will actually lower this rating to somewhere around 40, because the tile increases noise levels at higher frequencies. If you double the thickness of the subfloor and the ceiling wallboard panels, the net effect will increase both the STC and the IIC rating.