Tag Archives: flooring

Association Cooperation

In the October issue of The Construction Specifier, authors Ward R. Malisch, PhD, PE, and Bruce A. Suprenant, PhD, PE (both of the American Society of Concrete Contractors [ASCC]) wrote our cover story, “Bridging the Specification Gap between Divisions 03 and 09: Concrete and Floorcovering Associations Unite.” The piece looked at how their association teamed up with six other flooring groups to find a solution to a ‘specification gap’ between Divisions 03 and 09 in terms of floor surface flatness requirements.

For space reasons, we had to hold off including a little more background on how these associations collaborated. That ‘missing’ information follows, in the words of Malisch and Suprenant:

The impetus for developing the American Society of Concrete Contractors (ASCC) Position Statements came from a group of contractor members who became aware of a paper published by a national wood flooring organization—not, it should be noted, the National Wood Flooring Association (NWFA)—that stated the organization did not believe in F-numbers and felt they should not be used to measure slabs for gym floors. Rather than trying to decide how they could build a floor that meets unreasonable requirements, ASCC contractors realized they needed to spend their time and resources to educate the industry on the limitations of concrete floors. Thus was born this series, including ASCC Position Statement 6, Division 3 versus Division 9 Floor Flatness Tolerances.

Then, rather than continuing to fight their fellow contractors in the floorcovering industry, ASCC made an effort to get them on board, realizing the greater strength of a united front. ASCC first approached NWFA. With only minor rewriting, that association was eager to endorse the Position Statement.

“For the first time, instead of disagreeing, the two sides have come together to find a common solution to a problem that has cost both groups hundreds of thousands of dollars in rework,” said NWFA president/CEO Michael Martin.

Shortly thereafter, ASCC invited the National Tile Contractors Association (NTCA) to participate in a panel discussion on this topic featuring contractors and technical personnel from both disciplines. Both sides acknowledged the wisdom of a bid allowance to compensate for the incompatibility of the measuring methods, and NTCA became the second flooring association to sign on.

Bart Bettiga, NTCA executive director, commented on the reasons for the document’s usefulness.

“It is our belief this position statement is one of the most important documents we have supported in the past several years,” he said. “This statement accomplishes its goals on many levels. It educates the construction professional about important considerations that must be taken when specifying floorcovering products over concrete substrates.”

“The most important point emphasized in this position statement centers on the disparity related to meeting industry standards in the respective divisions,” Bettiga continued. “Equally important is the call for communication between the related parties and for a proactive approach to be determined prior to the commencement of the work. We strongly support the use of this statement to our members in their communication to the general contractor and architect/specifier on their projects.”

These two organizations were followed by the Flooring Contractors Association. Then, last year, Scott Conwell, director of industry development and technical services for the International Masonry Institute (IMI) contacted the ASCC, asking to add the group’s name, along with those of the Tile Contractors Association of America (TCAA) and the International Union Of Bricklayers and Allied Craftsmen (BAC) to the list of supporters.

“This ASCC Position Statement succinctly brings to light the disparity in requirements for floor flatness between the concrete and the ceramic tile trades,” says Conwell. “The paper effectively brings expectations in line, leading to increased cooperation on the job site to make any corrections to the floor that may be necessary prior to installation of the tile finish.”

Two trades with distinctively different practices and obstacles to overcome but with one goal: to deliver a high-quality product to a satisfied owner.

Improving Floor/Ceiling Sound Control in Multifamily Projects: Sound Testing Practices

by Josh Jonsson, CSI

The sound transmission class (STC) and impact insulation class (IIC) are ASTM-derived single number ratings that try to quantify how much sound a stopped by partition being tested.

Laboratory testing involves an ideal setting for the floor/ceiling assembly—it is isolated from the walls, and there are no penetrations for HVAC, plumbing lines, sprinklers, can lights, or electrical boxes. In the field (i.e. F-STC and F-IIC), the floor/ceiling assembly often sits on load-bearing walls, is connected to the structure, and contains many ceiling and floor penetrations for the items just mentioned. Consequently, the code allows for a lower rating for field scores over those in the lab.

The STC rating essentially tells how much noise is stopped from going through a wall. The test involves blasting loud noise at all the measured frequencies in a room. A Level 1 sound meter measures this exact noise in that room level at all frequencies, as well as the sound in the room on the other side of the partition. These two different levels are then essentially subtracted from each other, with some corrections made for background noise.

The IIC rating is not a comparative test like the STC. Rather, it uses an ASTM-specified tapping machine that sits directly on the floor—more specifically, directly atop the finished floorcovering. (Consequently, an IIC rating always lists the floorcovering with which it was tested.)

The machine has five steel hammers that spin on a cam shaft, falling onto the floor from the same height, no matter what or who is testing. These hammers put a consistent energy into the floor. The sound level meter is taken downstairs below the tapping machine and the sound level is measured at all the frequencies called out in the ASTM standard. These sound levels are plugged into the equations in the standard; a single number is generated summarizing how much sound was stopped.

To read the full article, click here.

Improving Floor/Ceiling Sound Control in Multifamily Projects

DSC_1207-2

All images courtesy Maxxon Corporation

by Josh Jonsson, CSI

In recent years, demand has increased for better floor/ceiling acoustics in multifamily construction. This has been driven by consumer desires, new guidelines from code bodies, and stricter enforcement of existing codes. How do design professionals keep pace as the traditional approaches to multi-unit residential sound control evolve?

This article reviews important new guidelines that must be taken into account by architects and specifiers, and examines how construction manufacturers have created new products or enhanced existing ones in the pursuit of achieving higher acoustical performance.

Thanks to product technology improvements and more stringent regulations, the wood-frame multifamily industry is paying increasing attention to the acoustics of the floor/ceiling assembly.

Thanks to product technology improvements and more stringent regulations, the wood-frame multifamily industry is paying increasing attention to the acoustics of the floor/ceiling assembly.

Two of the principal measurement standards for acoustics in multifamily construction are:

  • sound transmission class (STC), which pertains to the amount of airborne sound contained by a given building element (i.e. walls, doors, windows, and floor/ceilings); and
  • impact insulation class (IIC), which deals with impact noise (i.e. footfall, chair scrapes, and dropped objects) transmitted through a floor/ceiling system.

Both these single-number ratings apply to the full assembly of building materials used to separate tenants, including floor/ceiling assemblies.

For more than 50 years, these measurements have helped architectural project design teams quantify the acoustic levels of floor/ceiling assemblies. In fact, the Department of Housing and Urban Development (HUD) wrote A Guide to Airborne, Impact, and Structure Borne Noise: Control in Multifamily Dwellings in 1967, helping reinforce the importance of sound control in multifamily construction. This document, along with the Uniform Building Code (UBC), helped project teams recognize an acoustical threshold was needed in multifamily construction. UBC required an STC and IIC rating of 50 (or 45 if field-tested as F-STC or F-IIC). The higher the rating, the better the performance. (See “Sound Testing Practices.”)

In 1997, UBC gave way to the International Building Code (IBC) as the widely accepted model code. This shift brought greater awareness of acoustical ratings and their deemed thresholds in unit-over-unit construction, however these code levels remained aligned with the UBC’s established minimum requirements of STC and IIC 50 (or 45 if field-tested).

As the multifamily industry became more competitive, developers began offering upgrades in flooring and lighting to tenants as an amenity, yet little to no attention was paid to acoustical performance. This is astounding when one considers acoustics continue to be one of the driving factors in maintaining low vacancy levels, as well as one of the most litigated issues in this type of construction. To compound the subject, many of the amenity upgrades offered, such as hard-surfaced finished floors and canister lighting, can adversely impact a floor/ceiling assembly’s performance.

CS_July_2014.inddUpdating acoustical recommendations
In response to the need for updated acoustical guidelines, the International Code Council (ICC), along with several respected acoustical experts, created ICC G2-2010, Guideline for Acoustics. The guideline recognizes:

the current level and approach of sound isolation requirements in the building code needs to be upgraded. The requirements are currently insufficient to meet occupant needs.

As shown in Figure 1, the guide provides two levels of acoustical performance: ‘acceptable’ and ‘preferred.’ Both exceed code minimums for airborne and structure-borne noise.

These new levels now give a clearer direction on what levels should be targeted for desired acoustical performance, depending on the building type. As the names suggest, when one wants a building that has an acceptable level of acoustical separation, ‘acceptable’ is targeted. When one is designing a building on the higher end of market rate or luxury level, or has tenants or owners sensitive to noise, the desire should be for a ‘preferred’ level of performance.

Components of acoustical design
How do these new recommendations apply to the current approach for multifamily construction? As Figure 2 shows, a commonly specified design for many multifamily projects, which is also recommended by acoustical consultants, includes:

  • hard-surfaced flooring;
  • 25 mm (1 in.) or more of gypsum concrete;
  • 6.4-mm (¼-in.) entangled mesh sound mat;
  • wood subfloor;
  • wood floor trusses or joists;
  • insulation;
  • resilient channel; and
  • one layer of gypsum board.

CS_July_2014.inddThe typical rating for the design would be an IIC 51 to 55 and STC 56 to 60, depending on the floorcovering (e.g. laminate, tile, floating engineered wood), the acoustical performance of which would be listed by the consultant and verified by test reports. These numbers exceed code minimum and exceed the STC requirement for ‘acceptable,’ but only marginally—at best—meet an ‘acceptable’ level for IIC and any nuisance impact noises from upstairs tenants (IIC).

It is important to keep in mind these listed ratings would be achieved by selecting and installing all the components based on proper acoustical design. For example, the resilient channel would need to be a product similar to a proprietary one using steel measuring 0.5 mm (0.021 in.) thick by 38 mm (1.5 in.) wide, as opposed to a similar but lesser design lacking proper acoustical performance. To increase the IIC rating, an upgrade to the sound mat and/or the resilient ceiling system must be made.

Improving IIC ratings with sound mats
Traditional sound control mats with entangled mesh enhance IIC performance through the mesh being attached to fabric, which is loose-laid over the subfloor and then encapsulated with a gypsum concrete topping. The entangled mesh acts as a spring and produces an air space with little surface contact (i.e. three to five percent). Until recently, IIC performance was upgraded by using a thicker sound mat and deeper gypsum concrete.

Sound mat manufacturers have added new technology that allows for higher ratings while continuing to meet industry expectations for the corresponding thickness of the gypsum concrete. Traditional entangled mesh mats are now being manufactured with an additional acoustical fabric—Figure 3 depicts a 6.4-mm (¼-in.) entangled mesh mat with this upgrade. The acoustical fabric is laminated to the underside of the mat, creating an additional vibration break and absorptive layer. This improved product requires the same thickness of gypsum concrete as its standard counterpart. The IIC performance of the system is improved by two to five points without adding any measurable thickness to the floor system.

Another option is to employ the original 6.4-mm entangled mesh sound mat and a secondary topical mat placed between the gypsum concrete and the finished floor. If this option is selected, this secondary mat should be high-quality and thoroughly tested for sound ratings. (The sound test showing this type of product’s performance must be specific to the assembly that is being used versus a sound test from an unrelated design—for example, using concrete test data for a 2×10 joist system.)

CS_July_2014.inddImproving IIC ratings with resilient clips and channels
Properly installed, high-quality resilient channel will improve IIC ratings, but the resilient channel’s effectiveness can be easily lessened through faulty installation. To install traditional resilient channel, proper-length screws are imperative so as not to penetrate the joist or remove the channel’s resiliency.

Penetrations from the drywall into the joist through the resilient channel create flanking paths that transfer sound through a floor/ceiling assembly, as does having a channel affixed tightly to the assembly. For these reasons, new resilient clips that are difficult to install improperly have been introduced to the market. These clips can deliver equivalent performance to properly installed, high-quality resilient channel.

Hanging systems that provide spring and reduce or eliminate resilient channel contact with the joist offer even better performance. Figure 4 shows two such products: the ceiling wave hanger and a spring isolator. Either of these products installed in conjunction with a 6.4-mm (¼-in.) entangled mesh sound mat on the floor above would help the system exceed the ‘acceptable’ level, and approach ‘preferred’ levels for the IIC rating with hard-surfaced floorcovering. See Figure 5 for various assemblies and their acoustics attributes.

How to design for desired acoustical performance
As a specifier or architect team leader, one must first determine the level of acoustic performance to which to design. This should not be a matter of just meeting code—rather, the entire conversation must be approached in a new light. The following questions should be asked:

  1. When considering the amenities offered to tenants, how important are the acoustics of the unit? In other words, how important is the quality of life related to acoustical privacy?
  2. Does the project team want to just meet code because complaints and vacancy rates are unimportant or not a factor? Do they want ‘acceptable’ performance, significantly reducing noise complaints and removing sound control from the vacancy equation? Or, do they want ‘preferred’ performance to meet client expectation and greatly reduce potential for noise complaints?
  3. Once the level is determined, which method makes the most sense for achieving that performance level? Does the sound mat get upgraded to a very high-performing mat (manufacturers offer many styles with differing performances)? Does the sound mat get upgraded while keeping the system as thin as possible? Does the sound mat stay the same and the ceiling hanger system get upgraded? Is a secondary sound mat added while upgrading the primary sound mat and/or ceiling system to reach optimal sound ratings? Or, do the mat and ceiling get upgraded to reach better ratings?

CS_July_2014.inddEven after the desired level of performance has been determined, there are other factors that should be considered, such as whether the project will always be apartments or if they could become condominiums. There is also the matter of whether carpet and pad areas will always have carpet and pad.

Projects that start as apartments and then plan on being converted into condominiums should be approached as if they were condominiums from the beginning. Future owners may tear out carpet and replace it with hard-surfaced flooring.

Sound mat manufacturers receive a high volume of phone calls every year where a condominium project put sound mat only in the hard-surfaced areas. The new owners want hard surfaced flooring throughout and are being told they need to provide levels of performance similar to the ‘preferred’ levels while only being able to add a thin amount to the profile of the floor. As they can only do work in their unit, they are left trying to use a thin, lower-performing sound mat to reach the requested, more stringent criterion.

Acoustic qualities of various fl ooring assemblies.

Acoustic qualities of various flooring assemblies.

Conclusion
Throughout the United States, the wood-frame multifamily industry is paying increasing attention to the acoustics of the floor/ceiling assembly. Innovative architectural acoustic products continue to see greater use in existing metropolitan areas as well as in new areas of the country. It is important specifiers continue to be educated on new products and adapt their specifications to ensure they meet defined levels of sound control that tie directly to the end user’s satisfaction with their living space.

Josh Jonsson, CSI, is an acoustical specialist and West regional manager at Maxxon Corporation. He has more than 15 years of experience in the architectural noise industry and has worked for acoustical and vibration consulting agencies. Jonsson is a member of CSI, Acoustical Society of America (ASA), and ASTM International committee E33 Building and Environmental Acoustics. He can be contacted via e-mail at josh@maxxon.com.