The Salvador – Multifamily

When developing luxury hotel and condo units, sound transmission and privacy are a top concern.

During the design of luxury spaces the target STC for demising walls are typically above the STC 50 minimum, and are closer to 53-58 depending on location and luxury standards.

Instead of adding multiple layers of drywall to the assembly or using double studs to improve sound transmission, The Salvador in St. Petersburg chose to use Commercial Acoustics Wall Blokker sound membrane.

The Salvador is a 13-story green certified building which houses 74 luxury condo units and is located in the heart of downtown St. Pete.

Stadium Soundproofing – Atlanta, GA

Commercial Acoustics works with a variety of entertainment venues and sporting arenas nationwide, most recently assisting the Atlanta Falcon’s Mercedes-Benz Stadium in their stunning $1.5 billion stadium (complete with solar panels, fan plaza and retractable roof).

Inside the stadium in the premier seating will be ‘Super Suites’, private and personal boxes to accommodate fans looking for priority game day access and extensive catering and wet bar options. With all the perks and VIP access within the Super Suites, enhancing the game day experience by reducing sound transfer into the space was a top priority. During construction the architect and contractors researched sound-dampening options, choosing Commercial Acoustics Wall Blokker soundproofing membrane to be hung on the ceiling of the suites above the Acoustical Ceiling Tiles to deflect soundwaves and create privacy.

Using soundproofing membranes and techniques is becoming a more common feature in high-end venues when privacy is highly-sought.

Marchman Technical College – Educational, Acoustical Absorption

Noise control and sound privacy within educational settings are imperative. During the design process, target STC’s for walls should be discussed and mandated by the architect, but oftentimes topical acoustical treatment for larger spaces is held until after construction is complete. With the hard, reflective surfaces present within gymnasiums, cafeterias, and auditoriums, acoustical absorption is needed to maintain speech intelligibility and reduce reverberation.

The architects for Marchman Technical College consulted with Commercial Acoustics for their cafeteria space, where we supplied them with 100 PVC-wrapped baffles to absorb soundwaves. After installing the baffles, reverberation in the cafeteria space was significantly reduced and sound privacy was finally reestablished.

Luxury Timeshare Case Study – Orlando, FL

Testing and analysis were performed for a luxury timeshare in Orlando,

2 walls were tested: The wall between units 209A and 210A and the wall between 211A and 212A.

Both tests were performed late in the afternoon, around 5PM, when the construction on the adjacent job site was sufficiently low, but at times, still audible.

 

Description of Tests (2):

  1. Airborne Test (ASTC) was performed in accordance with ASTM E336 between units 209A and 210A in their respective kitchen/living room areas
    • This test was used to determine how much sound the wall assembly blocks between adjacent A Units.
    • The wall assembly tested was:
      • 1 Layer of 5/8” Type X Drywall Each Side, 1 Layer of 1/8” Wall Blokker Membrane One Side, 25-Gauge Steel Studs 16” o.c. and R-13 fiberglass insulation batting in the cavity
      • The wall assembly also included a hollow-core door in the center, a 4” air gap, and another hollow-core door. Each door had automatic door sweeps that were engaged.
  2. Airborne Test (ASTC) was performed in accordance with ASTM E336 between units 211A and 212A
    • This test was used to determine how much sound the wall assembly blocks between adjacent A Units.
    • The wall assembly tested was:
      • 1 Layer of 5/8” Type X Drywall One Side, 2 Layers of 5/8” Type X Drywall One Side, 25-Gauge Steel Studs 16” o.c. and R-13 fiberglass insulation batting in the cavity
      • The wall assembly also included a hollow-core door in the center, a 4” air gap, and another hollow-core door. Each door had automatic door sweeps that were engaged.

Summary Findings & Recommendations:

The two tests had very similar results, due at least in some part to hollow-core doors in the center of each wall. The test with the soundproofing membrane did perform at 2 points higher, achieving an ASTC (Field or Apparent Sound Transmission Class) of 46, while the gypsum-only wall achieved an ASTC of 44. The Florida Building Code, Section 1207.2, requires an ASTC of 45 for walls between adjacent dwelling units.

After testing was complete, a brief leak check was performed to determine where the majority of the sound was located. In the case of the first room, the sound level at the wall was 60.8 dBA, but reached 69.8 at the base of the door. The second unit had similar results.

Ultimately, combining the wall containing the soundproofing membrane with solid core doors between the units, and ensuring the door sweeps are adequately sealed, may result in an ASTC of 50 or more.

Figure 1: Door Sweep from 3” off of ground

 

Figure 2: Door Sweep from 1” off of ground

 

As you can see in the images above, the door sweeps may appear to be engaged just a few inches off the ground. However, by laying flat, you may be able to see any small gaps or “tilted” engagement of the sweep in a closed door.

 

Sarasota Aerospace Office

Testing and analysis were performed for a property manager working for a commercial property. One of their commercial tenants, an aerospace center at the property had concerns about sound attenuation between adjacent tenant units. Two adjacent legal firms, with very low background noise in their offices, could occasionally hear muffled conversations being held in the office next to them.

3 Airborne Tests were performed in accordance with ASTM E336.

  1. Between Suite 840 and 860, the eastern-most office
  2. Between Suite 800 and 840
  3. Between adjacent office space within Suite 840

 

Description of Tests:

3 Tests were performed at the property

Test #1: ASTC Test between Suite 840 and Suite 860

  • Measured ASTC of 43
  • Receiving room – general description: The room was furnished, with carpet and acoustic ceiling tile.
  • Source Room – general description: The room was furnished, and filled with numerous files and cabinets. It was an active legal office.
  • Relationship between rooms: The Source room was located directly adjacent to the receiving room and shared a wall.
  • All adjacent spaces were closed off with doors during testing.
  • Description of Test Assembly
    • 25 Gauge Metal Studs
    • 5/8” Type X Gypsum Board Each Side
    • R-13 Batting in Studs

Test #2: ASTC Test between Suite 840 and Suite 800

  • Measured ASTC of 39
  • Receiving room – general description: The room was furnished, with carpet and acoustic ceiling tile.
  • Source Room – general description: The room was lightly furnished. It was an empty office.
  • Relationship between rooms: The Source room was located directly adjacent to the receiving room and shared a wall.
  • All adjacent spaces were closed off with doors during testing.
  • Description of Test Assembly
    • 25 Gauge Metal Studs
    • 5/8” Type X Gypsum Board Each Side
    • R-13 Batting in Studs

Test #3: ASTC Test within Suite 840, between a conference room and an empty office on the westward side of the conference room.

  • Measured ASTC of 37
  • Receiving room – general description: The room was furnished, with carpet and acoustic ceiling tile. One line of walls was thin glass, while the opposite wall was windows looking out over the street below.
  • Source Room – general description: The room was lightly furnished. It was an empty office.
  • Relationship between rooms: The Source room was located directly adjacent to the receiving room and shared a wall.
  • All adjacent spaces were closed off with doors during testing.
  • Description of Test Assembly
    • 25 Gauge Metal Studs
    • 5/8” Type X Gypsum Board Each Side
    • R-13 Batting in Studs

Summary:

The design and construction of the walls tested is sufficient to meet the needs of most office tenants.

There are few attenuation codes defined and available for commercial office applications, and no attenuation building requirements.

Per one leading publication (Architectural Acoustics, Marshall Long), the recommended Field STC (now titled ASTC) for Normal Privacy at Normal Voice Levels is 32. Furthermore, Confidential Privacy may be attained at Normal Voice Levels with an ASTC of 38. All 3 of the walls tested meet or exceed this criteria.

Table 1: STC ratings needed to achieve Privacy at Normal and Raised Voice Levels

If further improvements are required by the tenant, they should be focused on the mullions and baseboards, and if significant improvement is needed, then a topical solution on the walls will provide a 4-8 STC improvement above the current configuration. Sound Masking is also a feasible solution, but should only be considered once mullion flanking is reduced to minimal levels.

Findings & Recommendations:

After ASTC testing was complete, we also performed leak checks along the wall in each of the 3 locations. In all 3 circumstances, significant flanking occurred along the mullions on the dividing walls, as well as secondary flanking along the baseboards.

No flanking was apparent along the ceiling. Walls continued up to the deck above the Acoustic Ceiling tiles. We used ladders to inspect the duct and piping penetrations, and all were visibly sealed with batting and caulk. Workmanship in this area was better than we usually see for ducting and piping penetrations.

1. Mullions: In all 3 tested locations, the sealing around the mullion appeared to be airtight. In these cases, the mass of the mullion alone (1/8” extruded aluminum) was insufficient to attenuate the same amount of noise as the metal-stud wall. In this case, the sound traveled the path of least resistance through the mullion itself. In a nearby, untested area there appeared to be a small gap in the mullion gasket.

  • Recommendation 1: The overall goal is to add further mass to the mullion. This is a perimeter, pre-constructed member, so modifications being made should be fully-reversible and made as a last resort. That being said, if there is an option to drill holes into the mullion and add blow-in insulation or other filler that will act to improve the performance.
  • Recommendation 2: Another option would be to adhere a thin membrane (Mass Loaded Vinyl, Wall Blokker, etc.) to the mullion on each side. These membranes are 1/8” thick and may be coated to match the existing

2. Baseplates/Bottom Tracks: In each testing area, there was some secondary flanking through the baseboards.

  • Recommendation: Remove the baseboards and apply acoustical sealant along the bottom of the drywall to make this gap as air-tight as possible.

3. Walls: While the walls themselves are sufficient to meet most client’s needs and expectations, additional soundproofing may be required in special circumstances (especially where confidential or private information is being shared). In this case, there are a few options:

  • Recommendation 1: Add a layer of mass-loaded membrane directly on top of the surface. This may be done rather economically, but outlets and other penetrations along that wall will need to be extended. Thickness of the membrane is only 1/8” thick, and should be applied along the entire surface. Expected sound-blocking increase is 20-30%.
  • Recommendation 2: Add a 2nd layer of drywall on top of the existing surface. The STC increase will not be quite as much as a membrane layer, but may be quicker to install. Expected sound-blocking increase is 15-25%.
  • Recommendation 3: If both of these options are undesirable, then consider implementing a sound-masking solution in the adjacent offices to minimize the speech intelligibility and articulation index of those next door.

Orlando Condominiums

The Cayman Condominiums were undergoing a renovation, its first in 20 years. While the existing structure and design were acceptable from an aesthetic and functional perspective, the contractor felt that they needed to address the one major complaint they were receiving – noise.

Metal stud walls helped reach STCs in high 40’s and low 50’s, but the residents at this luxury location had higher expectations. During the renovation, they called Commercial Acoustics to review the existing design and as-builts, and bring some new ideas to the table.

While implementing a soundproofing membrane in the walls allowed a significant increase in attenuation between units, we also worked with the architect to re-specify doors that would not allow weak-link propagation paths from room to room (a major complaint that previous tenants had).

While the flooring contractor was already familiar with our attenuation underlayment, we still had a technical rep out on site to ensure flanking paths were addressed and installation quality met our standards.

By implementing additional soundproofing materials and auditing installation techniques, our team was able to achieve STC and IIC ratings in the unit at 58 and 60, respectively.

Tampa Office Acoustics

An open office area was struggling with reverberation in their space and called Commercial Acoustics to help. We visited and found that unlike most open offices, that have issues with sound masking and speech privacy, this office setting did truly have unwanted echo in the space. This was due to a thin carpet, corrugated metal deck, and painted drywall.

Our team fabricated acoustic panels, baffles, and clouds, and used them in the space to deaden the excessive reverberation. We self-performed the install over a few hours, and finally provided their employees and staff the acoustical peace they were looking for.

 

 

Tropical Smoothie Case Study

As with many restaurants, Tropical Smoothie was suffering unwanted reverberation due to hard surfaces in their kitchen and dining area. We came on site and performed a reverberation test, then implemented a unique solution that improved their acoustics and aesthetics; a custom-printed absorption panel. The printing is done on acoustically-transparent fabric that allows the sound to transition into the absorbing core, made of mineral fiber.

The panel was custom-made over a 2-week timeframe, and installed on site in hours.

Office Space Vibration Testing – Case Study

Scope:

A property management firm has encountered complaints regarding structural vibrations in one of its commercial office properties in Lake Mary, FL. Specifically, occupants complain of annoying or distracting vibrations in the concrete slab, and some occupants have been concerned with potential structural integrity issues.

The property management firm has already hired a structural engineer to inspect the structure and found no safety issues. The engineer has suggested that the vibrating slab may be due to under-loading of the slab, since all of the occupants have not yet moved in, resulting in a lighter-than-designed live load. This results in serviceability issues due to footfall in certain areas.

Commercial Acoustics performed a vibration study to determine the root cause of the unwanted vibration, and whether the structure complies with ISO 10137 Standard vibration serviceability criteria.

NOTE: The criteria assesses only whether the structure complies with vibration related to serviceability and NOT for safety.

Scope

Testing was performed per ISO 10137 “Bases for design of structures – Serviceability of buildings and walkways against vibrations”.

Three uni-axial accelerometers were used to measure the vertical vibrations incurred during a standard work day on the 3rd floor of their building. The sensors were placed initially at workstation 4183, which was the location of one of the chief complainants. The complainant was also present at the time of the testing and noted that she takes motion sickness medicine throughout the day to prevent nausea.

It should be noted that certain individuals are more sensitive and susceptible to vibrations, even if these vibrations are beneath commonly-accepted levels, and our mitigations list some areas in the office that may be more acceptable for those employees.

Vibrations at a second location were also tested, but found to be lower in magnitude than workstation 4183. As identified in the structural layout (Figure 3), workstation 4183 was mid-span between the beams and joists crossing the floor, likely contributing to the greater vibration magnitude.

They were placed in a layout running horizontally across the floor, perpendicular to the W21x44 beams that were spaced 10’ apart.

According to the standard, the vibrations were described as Class 3, corresponding to distinctly Perceptible but not strongly perceptible.

Instrumentation

Crystal Instruments Spider 20 Data Acquisition Unit, Serial #: 5462944

PCB Piezotronics Single-Axis Accelerometer, Part #: 393B04, Serial #: 36913

PCB Piezotronics Single-Axis Accelerometer, Part #: 393B04, Serial #: 36795

PCB Piezotronics Single-Axis Accelerometer, Part #: 393B04, Serial #: 36783

PCB Piezotronics Single-Axis Accelerometer, Part #: 393B04, Serial #: 30743

Source of Vibrations

Figure 1: Vibrations due to Walking

After review of the data, there is no pattern to indicate that the vibrations are due to mechanical equipment. This would usually be indicated by periodic changes that were of the same length and magnitude. A brief demonstration was performed by bouncing on the balls of the feet and simulating walking down the hallway. Both demonstrably influenced the transducers, indicating that the source of the vibrations is staff movement. As seen in Figure 1 above, each incident of significant floor vibrations corresponded directly to staff or technician movement. All of the five aforementioned events vary in magnitude and duration but represent the individuals nearest the testing equipment departing their desks for various tasks and returning to their desks.

After discussions with the staff, it was further verified that the vibrations were sporadic throughout the day. This is common in floors with intermediate spans (between 10 feet and 30 feet) because the structure has insufficient stiffness or mass to reduce some vibration.

Figure 2 outlines the five RMS (Root-Mean-Square) signals with the greatest magnitude. All are from the first two hours of the day, with measurements taken between 8:44 and 10:44 AM, presumably because that is when the majority of the foot traffic occurred on site.

Figure 2: Vibration Magnitude for Each Test, m/s2 versus Frequency

These vibration levels are well below the acceptable limits in ISO 10137, shown on the right side of Figure 2. This graph shows the magnitude of vibrations in acceleration (m/s2), which peaked at about one level of magnitude below the acceptable limits.

Figure 3: Structural Drawings of 3rd Floor

A second set of readings were performed at Testing Location 2, as requested once the team arrived on site. As seen in Figure 4, the magnitude of vibration at the second location was significantly less than the magnitude at Testing Location 1. This is likely due to the proximity to the larger beam in the core of the building. Testing Location 1 is located at mid-span between the larger, stiffer beams.

Figure 4: Magnitude of Vibrations at 2 Different Testing Locations

Path of Vibrations

The testing data indicate the vibrations are propagating through the deck from adjacent footfall. The flooring system consisted of thin Carpet on Concrete (3” Concrete on 3-1/4” Corrugated Deck). No cushion or underlayment was installed under the carpet.

Mitigation Options

Since the office space is fully built-out and in use, construction methods such as stiffening the floor with additional beams are not desirable. However, a number of options are still available, listed below.

  1. Vibration-Reducing Mats:
    • Type: Topical or Underlayment: Since the flooring system is already installed, it would likely be cheaper and faster to install a topical sound reducing mat on top of the existing floor system. A pad such as Pliteq’s GenieMat FIT would be acceptable. This mat will isolate the footfall before it becomes structure-borne in the slab, and will result in a reduced vibration load in the nearby workstations. Other products, such as Commercial Acoustics’ Floor Blokker would be acceptable if installed under the carpeting.
    • Location: Hallways or across the entire floor: It is recommended to only install this pad in major walkways, since that is where the majority of the footfall is occurring. While this will not isolate footfall in certain pods, it will address the majority of the footfall while saving significant cost in material and precluding the need to move the existing office equipment.
  2. Rearranging Office Employees
    • As mentioned above, some office employees are more susceptible to vibrations and movement than others. Relocating these staff to more stable portions of the building, especially near the corners and directly next to the central beams will minimize the level of vibrations they feel. Corner locations nearest to two thick beams will be the most stable.
  3. Future Designs
    • By placing beams and joists closer together, the structural engineer may greatly increase the stiffness of the structure so that vibrations due to footfall are not perceptible by employees. Likewise, keeping the same span lengths the same but increasing the depth (and therefore mass) of the floor will result in a heavier floor that will respond less to human-induced movements.
    • Simply implementing a dampening underlayment during construction will also reduce the acceleration induced from human movement on the concrete slab.

Conclusion

The vibrations in the office space, while clearly perceptible, were not above the suggested thresholds identified in ISO 10137. While this is a good indicator of the serviceability of the structure, implementing Mitigation Options listed above will reduce the vibrations felt by employees and staff in the office area.

Student Housing – Case Study

CA Ventures is known for developing well-built, high-performing student housing complexes nationwide. When they were looking to develop a multifamily project close to Auburn University, comfort, aesthetics and amenities were a top priority. Located in the heart of downtown Auburn, Evolve Student Apartments stands 9 stories high, fully furnished with the highest level of amenities for residents.

The desire for a high level of tenant comfort and privacy began early in the design phase when the architectural firm contacted Commercial Acoustics to discuss wall and flooring assembly treatments. Unlike other student housing and mixed-use projects we’ve worked on such as The Village Promenade and 9 on Canal at Ball State University, Evolve’s sound concerns were from adjacent apartment dwellers, not external noise entering through windows from bars, street noise or shopping plazas. Consulting on the project we provided technical data, modeling out various assemblies and costs to ensure a target STC of 50+ would be achieved.

Instead of hanging multiple layers of drywall where you get diminishing returns and a longer installation time, our 1/8” Wall Blokker sound membrane was installed directly on the wood studs easily and fast with no seam taping required. By having the ability to consult and discuss with the architectural team we were able to increase the STC of the demising walls, reduce cost and achieve a quality living environment for tenants.