Soundproofing a Smart Home

A new-construction custom home was being completed in Tampa, FL in February 2017. Outfitted with some of the most recent technology, the owner was concerned about excessive noise from the playroom and entertainment room upstairs, as well as insulating the Master Bedroom downstairs. The framing was made of 6” wood studs, with ceilings at 12’ and an isolated Master Bed-Bath suite.

After an initial site visit, we determined the ideal approach of implementing a soundproofing membrane directly to the studs downstairs, and completely isolating the master bedroom suite. Upstairs, the Wall Blokker PRO was utilized in the entertainment and playrooms to ensure the speaker system would not disrupt activity in other portions of the home. Our approach was consistent with general guidelines to soundproofing a smart home.

While the initial discussions also included membrane in a side room, we decided to remove the STC product at that location due to the flanking paths available in the doorways (a critical weak-link often overlooked in the soundproofing schema).

The smart home owner was also interested in soundproofing the 2nd story flooring system, since the footfall of children and visitors had been easily audible in previous homes. This was addressed by adding the Floor Blokker membrane directly to the plywood sub-floor upstairs, which was then covered with a hardwood top floor. While a resiliently-mounted ceiling was not installed downstairs, the membrane was still able to increase the estimated IIC in the system from the low-30s to approximately 45.

Overall, STC and IIC ratings for the home were improved at the most critical locations (and removed in locations where improvement was not necessary). Our team installed both flooring and wall applications in a single day, and returned the following day to Quality Check and ensure all installations met our strict standards.

Clean outlet cuts were made, wall-floor intersections caulked, and a debrief with the contractor performed to ensure proper installation of drywall and ultimately, superior performance of the system.

A soundproofing project of this magnitude should typically run about $3,000-$7,000, depending on the size of the home and number of floors. Since premium soundproofing membranes weigh approximately 1 pound per square foot, the logistics of moving large quantities up flights of stairs becomes time-consuming. Furthermore, wall heights and floor footprint must be taken into account to determine the required number of cuts and splices. Hiring an experienced team to design, install and/or inspect the soundproofing work makes the difference between a moderate improvement in sound attenuation and a major breakthrough!

Luxury Theater Soundproofing

Theater Soundproofing

One of the most ideal uses for soundproofing membranes is when low-frequency reduction is critical to the performance of a system. This is especially true with entertainment and industrial venues, where low-frequency noise is generated from equipment and amplified speakers.

A recent case study with a luxury cinema in Dallas, Texas serves as a prime example. The client required an STC of 65 for the wall performance, but more importantly, needed attenuation above 20 dB in the 50-80Hz range. This is difficult, if not impossible, to achieve with conventional methods, including multiple layers of drywall on double metal-stud walls.

With gypsum-only assemblies an STC of 65 may be reached, but the attenuation (transmission loss) at 50 Hz is often around 8-12 dBs. Furthermore, this data point is not factored into STC performance, since STC only incorporates performance between 100-4000Hz.

Instead, we worked with the client’s architect to implement a hybrid solution with 1 layer of drywall on each side, and 1 layer of membrane applied directly to the studs behind the drywall. We used the INSUL software to model the system, and determined that this should provide a significant improvement in the low-frequency and broadband attenuation characteristics for the wall.

Once confirmed, we scheduled a test with Riverbank Acoustical Labs to run a custom test for this system, and received the results within 2 weeks. As expected, attenuation at the critical lower frequencies was 60-70% higher than the gypsum-only design. This is primarily due to the resonance of the wall, as the membranes provide a damping of the system while gypsum transmits sound energy through multiple layers if directly attached.

33 foot rolls were custom-produced and delivered to the job site to optimize the installation and maximize schedule recovery. Each roll was hoisted on the scissor lift and attached via 4 screws along the header track of the stud system. The lift was then lowered while the roll unspooled from the lift bar. This allowed the membrane to be installed at 3-4 times the rate of standard drywall.

The results were excellent – our client received a benefit in each of the cost-schedule-technical legs of the typical construction triad.

Cost: Significantly reduced drywall labor out-paced the increased cost of the soundproofing polymer membrane. Furthermore, the lighter-weight wall allowed further stud spacing, saving further material and labor costs.

Schedule: Since the drywall construction was on the critical path, it was essential to reduce it where possible. The membrane installed in each auditorium in less than 1 day, compared to 2 days for drywall. This allowed significant schedule recovery on the project that had been affected by inclimate weather.

Technical: Low-frequency attenuation was improved by 60-70%, especially in the “problem range” from 50-200 Hz. Furthermore, the STC was improved by 3 points overall.

Exterior Noise Control – Tampa Yacht Club

Yacht Club Acoustic Model

The Tampa Yacht and Country Club was struggling with an exterior noise issue. While it is a beautiful venue with a history of hosting elegant events, this also led to large wedding parties that sometimes were louder than local neighbors appreciated.

While the club (TYCC for short) hosted parties for years with little issue, a changing noise ordinance code in the City of Tampa was on a collision course for the Board of Directors. The traditional code required dBA and dBC thresholds at the property line, while the new code added in another requirement; that the noise was not “plainly audible” 100 ft from the property line. This code change significantly increased the concern for violations, so they contacted Commercial Acoustics to help.

The club had a challenge from the start, since their outdoor patio was a preferred venue, with unique tiled floors and open lawn. When the band set up here, there was excellent line-of-sight to all of the guests, but no borders or perimeters to attenuate the noise prior to reaching the property line.

An initial assessment was performed to quantify the existing noise levels, which occasionally peaked over 55dBA at the property line at night. Note that these measurements are made as 10-second averages, so that peak noise impulses do not automatically constitute a violation. Over the course of the evening, as the guests grew louder and the band amplified their music further, the noise issues sometimes grew worse.

Yacht Club Acoustic Model
Tampa Yacht Club Acoustic Model

It was clear that the club needed a 10dB reduction at the property line to minimize risk of aggravating nearby residents. Our operations team found a number of suitable locations to support sound-reflecting membranes on a nearby fence as well as supported directly from the overhanging tent. Meanwhile, our lead consultant modeled the effectiveness of this approach, and determined the expected sound levels at the property line after implementation.

Following a morning install (just before a wedding), the results were measured that evening, and found to reduce the noise levels by 15dB directly behind the venue, and 12dB at the property line. The Blokker panels were also hidden behind decorative sheer curtains so that guests weren’t even aware they were there.

Fence Blokker Panels
Fence Blokker Panels
Acoustic Measurements
Acoustic Measurements at Property Line

Further operational suggestions were made to club management, including loudspeaker control processes and re-orienting the stage.

The TYCC executed the option to purchase the membranes after the initial rental period, and have used them in the field since with excellent results.

The issue that the Tampa Yacht and Country Club faced were not at all unusual from what many of our clients deal with – unexpected noise problems that arise with unique constraints, and that often require unique, but cost-effective, solutions.

Historic Fenway Hotel

Fenway Hotel Soundproofing

Initially opened in the 1920s, the Fenway hotel is due to be reopened later this year as a boutique hotel. While the transformation included cosmetic and functional upgrades, there was one portion of the hotel renovation that called for soundproofing expertise – the noise transfer between rooms.

Construction technology has come a long way in the past century, and with it have come benefits of additional privacy and comfort. Adding sound-blocking layers in a historic hotel, with limited space already, proved to be a real challenge. As we’ve discussed in previous articles, resilient channel can be a feasible solution on wood stud construction (which includes the Fenway), but in this case, the architecture firm couldn’t afford the extra several inches per room (not to mention the installation concerns).

The construction consisted of 2”x6” stud walls with immediately adjacent rooms, leaving limited options. Our team of acoustical consultants reviewed the geometries and target STCs, and provided our solution – Wall Blokker PRO on each side of the assembly, with Floor Blokker on the wood joist flooring systems. Within weeks, our team installed the solution and tested it for effectiveness. While the confined space limited the STC performance, we were able to surpass an STC of 50 at a cost-effective price.

The Fenway is a new type of clientele that is relying on Commercial Acoustics to provide a soundproofing solution on budget, within schedule, and to soundproofing levels that were previously unavailable with conventional construction techniques.

Soundproofing for Movie Theaters

When designing or building a new movie theater, it is critical to consider the movie-watching experience, from seating locations to auditorium reverberation and attenuation between adjacent theaters.

One of the top complaints we see in theaters is walls meeting high-STC requirements, but insufficiently designed to block the low-frequency noises that are most distracting (and annoying). As one consultant recently noted, STC should stand for Speech Transmission Class, since it is best used as a single-number guide in offices and other speech-constrained environments.

Ultimately, to reach acceptable dB transmission loss levels below 1000 Hz, you need at least a double-stud wall with a 2” air gap between the parallel studs. Traditionally, this has been used with multiple layers of drywall on each side – the most common combination we see is 2 layers one side and 3 layers on the other side. Unfortunately, this is a very inefficient way to achieve higher STCs, since the adjacent drywall layers are directly attached, meaning the sound travels directly through the layers. Furthermore, we’ve seen a significant rise in complaints with CMU-based walls, even when resiliently mounted drywall is incorporated and the cells are filled. These provide significant mass between the source and receiving rooms, but not enough decoupling between the rooms to attenuate low frequencies.

Instead, many architects and consultants are implementing soundproofing membrane layers in their designs. These offer some decoupling capability, while achieving higher STC and low-frequency attenuation than their corresponding gypsum-only walls.

For instance, consider a wall with gypsum-only (5 layers) versus membrane (2 layers membrane and 2 layers drywall). The former achieves a transmission loss of 48dB at 315Hz while the latter achieves 58dB loss at the same frequency. This 10dB increase is equivalent to cutting the sound power by 50%.

Some 3rd party theater-certifying bodies, such as THX, have specific low-frequency targets that are well above what a standard STC 70 wall will block. Therefore, it’s critical to consider not only the overall sound-blocking of a wall, but specifically it’s low-frequency attenuation capabilities.

Understanding IIC Claims for Soundproofing Underlayments

It’s a common occurrence: you see a 1-page data sheet claiming light-weight and inexpensive materials getting IIC ratings of 70 or higher. These data sheets are littered with incomplete information and undefined assemblies.

When you request the test data, it’s either difficult to attain, or when received, completely irrelevant.

So, where do you go from here?

The number one thing Acoustical Consultants recommend today is requesting exact attenuation tests from a third party lab. This removes the conflict of interest inherent between a technical and marketing team. When reviewing tests, find applicable configurations that are as close to your floor design, and make extrapolations from there if needed.

For instance, you may see an underlayment that shows an IIC of 55 on 6” light-weight concrete and acoustical ceiling (resiliently mounted 5/8” gypsum board), and with ¾” OSB and ¾” Gypcrete above. If your assembly design is similar, but with 1-1/2” Gypcrete, then you may add 1-2 points. The PCI (Prestressed Concrete Institute) has extensive data on incremental changes in building materials. On the other hand, if your reference design has no resiliently mounted ceiling, then you will need to remove 8-10 IIC points (as a rule of thumb). Better yet, request the same test from your supplier without an acoustic ceiling – top soundproofing vendors have numerous tests in dozens of configurations.

For further reference, see the list of 3rd party tests performed on the Floor Blokker membrane here. Acoustical technicians are available to answer any questions that you may have.

Exterior Noise Control

While there is significant literature and testing available for interior wall partitions, many planning and architect professionals run into issues of exterior noise control.

In Europe, where often-times it is required to perform a Sound Study prior to new development, the US and many other countries are in a build and react mode. This sometimes leads to liability concerns, when there are few mitigation options available after construction.

The most Common Complaints are roadway noise (linear source) and outdoor construction or industrial activity (point source). Generally speaking, the easiest way to deal with these issues.

1. Barriers

Outdoor barriers can be a very effective way to attenuate unwanted noise off of highways or from music venues. These are often seen as pre-cast concrete structures on the side of interstates, but may also include aluminum soundproofing panels near above-ground transit systems or flexible sound-blocking polymers near construction projects. The key to any effective barrier system is its height, proximity to the noise source, and barrier material. As a rule of thumb, the closer, taller, and thicker a barrier becomes, the more sound it will block. See the image below for an illustration.

The initial path of propagation was D, the distance from the source to the receiver. The sound must now travel up and over the barrier, a total distance of (A+B). The greater tha (A+B-D) becomes, the greater the difference in sound attenuation. This total value is higher (given a fixed barrier height) if the barrier is located closest to the source or receiver locations. Ultimately, the barrier should have a mass of at least 2 lbs/sq ft to ensure the diffraction up and over the wall is the primary constraint, rather than the transmission loss through the barrier.

2. Spacing

Another rule of thumb is that the Sound Power decreases by 6dB for every doubling of distance from the source. This begins at 25′, then again at 50′, 100′ and so on. So a concert at 100dB would be 76dB at 200′ away – a significant drop, but still well above most noise ordinances. It may be less if the sound is traveling over a lake or other water body. However, the amount of sound loss may be improved by up to 10dB every 100′ with “Heavy Vegetation” (these should be large-leaf plants that are thick all the way to the ground).

3. Noise Source

Consider the noise source and how “annoying” it can be to the receiver. Steady drones from highways are less invasive than loud impulsive noises such as gunfire or hammering. As a rule of thumb, below is a table that illustrates noise coming off of a highway or primary road, and the suggested barrier height needed to achieve common background noise levels.

4. Composite STC

Ultimately, the noise from the roadway or exterior source will be reduced by the facade of another building. However, when considering the level of attenuation a building provides, you must calculate the “Composite STC” – that is, a combination of the strong and weak facade elements that gives the total Sound Transmission Class of a building element. Unfortunately, a brick wall (STC ~55) with single-pane windows (STC ~25) will have a composite STC weighted heavily toward the windows, perhaps as low as 26-27 depending on the amount of window area. When this is the case, it is critical to treat the “low hanging fruit” (windows and other openings) to ensure that the overall sound-blocking most effective.

To learn more about soundproofing options, reach out to one of our consultants and schedule an initial meeting. We are headquartered in Tampa, FL, but provide soundproofing solutions across the Southeast and special projects across the US.

 

Acoustical Consultation and Testing

Commercial Acoustics was contracted to perform consulting services for a multi-family property in upstate New York where residents were complaining of excessive noise, particularly from adjacent stairways and from footfall above. After initial review and discussion with the client, Commercial Acoustics traveled to the site and performed a number of acoustical tests for structure-borne (AIIC) and airborne (ASTC) attenuation between units.

After performing the tests, our analysis determined that certain products offered the most cost-effective solutions to increase the sound-blocking between the units at an affordable cost.

Brief Synopsis of Test Method:

The airborne test was performed by placing a loud speaker playing pink noise in the corner of the room, and turned up so that it was at least 10 dB above the background noise in the receiving room. Measurements were taken in each room by frequency segments, from 100 Hz to 4000 Hz. Then, a calculation was performed to determine the Apparent Sound Transmission Class (ASTC) of the wall in question.

A similar method was used to measure the structure-borne attenuation of the floor between and upstairs and downstairs unit. A tapping machine is used to drop 500g stainless steel balls onto the floor at a predictable height.

The tapping machine may also be operated remotely to save time while walking between the upstairs (source) and downstairs (receiving) units.


 

Investigation:

After testing was complete, the room was swept to search for paths of sound leak between the units. The meter peaked near the stairwell wall, and again near the baseboards, where we predicted that acoustical sealant was not used. However, there was a significant peak along one portion of the wall, where an arrow was drawn.

After taking the baseboards off and cutting the wall open, a knot was discovered in the wood that passed along the entire baseplate, allowing significant sound transmission from the source room to the receiving room.

Furthermore, the ceiling in the lower unit was later cut open, and revealed a number of construction flaws. The tenants complained that when neighbors above walked on the vinyl flooring, the ceiling fixtures would shake. We discovered that the strongback that was designed to hold the web trusses together was not fastened to the trusses, allowing them to move independently. This resulted in significant weaknesses in the low frequency attenuation of the construction element.

Worse yet, standard hat channel was used rather than resilient channel, resulting in a significant loss of decoupling in the floor-ceiling assembly.

Recommendations:

After the report and testing analysis was complete, we provided a list of potential solutions for the property, including likely lead time, cost, and predicted effectiveness. After careful review of the pros and cons of each solution with the client, a prioritized list was submitted as the final deliverable.

Since the ceiling channel could not be replaced easily, a flooring underlayment was specified under the LVT above to isolate footfall. Future phases of this property will undergo evaluation during construction to review for similar flaws. Acoustical sealant was used along the entire wall with the sound leaks, including liberal use of sealant along knots and other material defects.

The testing and solution were completed within 2 weeks of contract, and we continue to work with this General Contractor client on future vacation rentals and multi-family properties.

Commercial Office Sound Treatment

KForce’s international headquarters are located in Ybor City, near downtown Tampa. However, they have field offices throughout the country where dozens of employees work in an open office setting, creating a noisy environment. Nearby are conference rooms that require some noise reduction, and just beyond that are interview rooms, which require sound privacy – for both comfort as well as protection of sensitive information.

This is a common layout that challenges many corporate clients that need to balance square footage price constraints with the real need for privacy.

We consulted the KForce development team and determined the most significant cause of concern in future office buildouts – the transition area from the bullpen to office and interview area.

(While seemingly apparent, many commercial office clients have their greatest noise disturbances in the bullpen itself, where sound masking alone may be used to create a more cohesive atmosphere).

Because non-load-bearing metal studs were used, the Wall Blokker soundproofing membrane was sufficient to attain an STC of 56 on those walls at a reduced cost to the client. Meanwhile, several of the walls were not extended to the deck near the conference room. Since the design was already complete, it was easier to treat the ceiling tiles than to extend the walls. Drop Ceiling Noise Blokker was applied to each of the ceiling tiles in the transition zone to require the sound to increase its path by as much as 80% in this area.

After installation, significant noise reduction was achieved, with sound in the office transition zone to the conference room down by 65% or more, while the interview rooms exceeded their privacy index goals.

The total cost of the project was well below $10,000 and did not affect the critical path of the construction, resulting in no schedule impact.

If your commercial office space could benefit from sound masking or acoustical attenuation between sensitive areas, reach out to one of our technical consultants today.

Multi-Family Soundproofing

luxury multifamily soundproofing

In many parts of the country where acoustic tests are not mandated prior to completion, there has been a growing number of class-action suits and corresponding renovations to multi-family developments. Often, one of the most straight-forward mitigations developers and architects can make is adding a flooring underlayment to reduce structure-borne noise in units above; mainly, footfall.

We recently treated a facility in Austin, TX that experienced superior IIC and STC ratings in their Open Web Truss flooring system by implementing the Floor Blokker membrane beneath the hardwood floors. After installed, an independent acoustical consulting firm, BAI, performed fields tests and found an ASTC of 58 and AIIC of 52. The corresponding lab test values are 63 and 57, respectively.

75,000 square feet of Floor Blokker was installed at less than $1/sq ft and this luxury apartment complex was able to completely eliminate noise complaints and reduce long-term tenant turnover.

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