Wall Blokker vs Acoustically Enhanced Gypsum Board

Acoustically enhanced gypsum board, such as Quiet Rock or SoundBreak, is commonly used in the construction of high STC (sound transmission class) wall and ceiling assemblies. It contains a viscoelastic gel layer in the center which is sandwiched between two thin drywall layers. Uses include but are not limited to educational, healthcare, commercial and multifamily projects.

While they are ideal if space constraints are critical, there are other products that achieve a higher STC at a fraction of the cost if small footprint concessions can be made.

Soundbreak and QuietRock Alternatives

SoundBreak and Quiet Rock drywall does have its pros. They get hung like traditional drywall for a ‘fool-proof’ installation every time unlike resilient channel which has very challenging installation requirements. The material cost however is 5x more expensive than traditional drywall, and due to the core density, the weight of the product often causes increased labor costs from contractors. Whereas acoustical drywall is approximately 2 lbs per square foot, many EVA membranes are approximately 1 lb per square foot, and therefore much more easily maneuvered at height.

When analyzing cost and effectiveness, a strong VE (cost-saving value engineering) option for this product is a soundproofing membrane which would get hung on metal or wood studs underneath traditional drywall. Instead of paying a premium for a gel barrier within the drywall, installing both pieces separately will save substantial cost. The Wall Blokker soundproofing membrane combined with traditional 5/8” drywall will outperform acoustically-enhanced drywall by 3-5 STC points on the same assembly, roughly saving $1.70/sf vs. Sound Break XP. See data below:

Soundproof Your Smart Home

As the amount of technology and automation grows in new “Smart Homes” across America, there is another silent, growing problem – soundproofing. These homes are outfitted with 7.1 speaker systems, entertainment centers, in-home theaters, and even music studios. However, all of this technology integration can create a noisy environment that installation firms don’t always know how to address.

In these cases, a systematic approach to acoustics and soundproofing should be considered. Often-times there are 1-2 “critical” areas in the home that must be addressed above all others. Whether it is the source room (outlined above), receiving room (such as a Home Office or Master Bedroom), or flanking paths (outlets, ducts, etc.), the designer should consider the cost and schedule impacts of improving the STC or IIC ratings of the systems.

All acoustical designs begin with the Source-Path-Receiver approach to determine how best to treat the problem. It can be very cost-effective to soundproof a theater room with soundproofing membranes, for instance, but a shared ducting system between the two may limit the effectiveness of this approach. By beginning with a general approach, the designer may find multiple solutions, then down-select to the one that is most cost-effective.

Options available to designers include:

  • Improving STC performance of walls – all walls do not need to be treated equally. If the theater and master bedroom are completely isolated, then utilize more cost-effective approaches in other locations.
    • Staggered or double-stud walls
    • Soundproofing Membranes
    • Fiberglass or Mineral Wool insulation
    • Locating buffer areas (closets, pantries) around louder areas (AC units)
  • Improving IIC performance of floors
    • Using higher-IIC top floors, especially plush carpet
    • Using underlayments, especially under poor performers, such as hardwood or tile
    • Resiliently-mounted ceilings where possible
  • Treating Flanking Paths – perhaps most critical, especially in smart homes
    • Caulk all wall penetrations (ducting, pipes, etc.)
    • Use putty pads and caulk heavily around outlets on critical partitions
    • Use solid core doors with tight seals around the threshold and jamb
    • Use branch ducting that separates vents going to and from studios or other loud locations to other critical locations in the home

An experienced soundproofing designer and installation team will consider all soundproofing options, and implement the one that is most cost-effective and beneficial to the home owner.

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.

 

Restaurant Acoustical Absorption

Cena Restauarant

While many restaurateurs struggle with acoustic issues, some are more critical than others. Take for instance, Tampa’s downtown Channelside restaurant Cena. A high-end Italian Cafe focused on upscale Mediterranean cuisine, the restaurant was a perfect storm of underlying acoustical concerns. The walls were painted gypsum with a significant square footage of windows. Meanwhile the tall ceilings created a large volume with little porous material to absorb the dinnertime conversation. The result – an echoey room that made conversing difficult.

With a limited budget and tight timeline before the holiday season, Cena management reached out to Commercial Acoustics for a cost effective solution. We measured their reverberation time of approximately 1.1 seconds, relatively high for a commercial dining space. After simulating the proper amount and type of absorption material, we proposed the solution to achieve 0.7 seconds, ideal for this type of restaurant. The solution included 2” thick fiberglass clouds and panels – capable of absorbing the low frequency discussions.

Within weeks we manufactured the ceiling clouds and panels in-house and coordinated installation. All fabric finishes were reviewed with the client and not only blended in but enhanced the existing décor. Installation occurred during closed business hours and was completed in a single afternoon. We measured reverb time afterwards and it met our target decay rates, but would it stand the true test? We met with Cena’s owner who was pleasantly surprised and stated “The panels really work! I had dinner with several friends and the place was packed and we had great ability to converse”.

We were able to provide this customized, acoustical solution before the busy holiday rush of patrons. Better yet, the manufacturing and installation took just over 3 weeks and we were able to deliver results to the client for under 6K.

Sound Masking for Open Offices

Sound Masking Unit

In open layouts – whether it’s offices, libraries, or museums – noise often becomes a major concern. Without a proper background noise, loud noises are particularly distracting, due to the Dynamic Range that occurs (difference between quietest and loudest moments). Large dynamic ranges make it difficult for employees to concentrate or visitors to enjoy the space.

We apply the ABC (Absorption, Blocking, Cover) approach to many of our consultations, but open spaces often don’t allow for sound-blocking solutions, and additional absorption makes little or no improvement.

Sound masking is the addition of a white noise or pink noise system of light background sound. This particular frequency of sound essentially helps break up the silence and reduce audible distractions of human speech or impulse sounds. When used correctly, sound masking systems allow for greater productivity, increased privacy and comfort and a more enjoyable workplace.

Speech privacy and sound masking go hand-in-hand. Speech privacy is the ability of an unintentional listener to overhear and understand another person’s conversation. This is common in large ‘bullpen’ open office environments or in adjacent offices where walls don’t go to deck and sound has a clear flanking path to transfer in and out. Not only is a lack of speech privacy distracting it can also become a breach of confidentiality in law offices or physician patient rooms.

One recent project Commercial Acoustics treated was a library in Pinellas County, Florida. Readers were often distracted by a “Makers Area” where louder interaction was common. Since the wall didn’t go to deck and deck and it wasn’t possible to add a barrier between the areas, sound masking was the obvious solution. Masking consists of speakers that hang above the area (often concealed by ceiling tiles) that create a constant, homogeneous background noise at a decibel level that the visitors don’t notice but masks unwanted sounds. In this area, we spaced the speakers at 15 ft on center, and implemented a 45 dBA background (lower than most office settings). Within 2 weeks and at about $1 per square foot, the masking system was installed and calibrated, allowing the library to prevent future noise complaints and improve its visitors satisfaction.

Sound Masking Layout

Common Wall STC Values

Target

When designing or building a wall partition, it’s critical to understand what benefits you’ll get out of the wall assembly, and the associated costs and complications that come with more complex assemblies. The first step is to determine target STCs – how much sound do you need your wall to block? This is often dependent on the use-case of the room, and the expectations of the tenants. Just as walls in a doctor’s office may vary with those of a daycare, you’ll also have different expectations at an affordable housing development than a high-end luxury condominium.

There are numerous tools across the internet to calculate the STC of your wall design. Be sure to compare apples-to-apples, since some products may advertise an STC, but change the underlying wall assembly.

Below is a list of STC values for common partitions and assemblies, along with their estimated speech privacy and ideal applications in the real world. By utilizing soundproofing membranes and other material on the market, you can achieve these STCs at prices that weren’t previously possible with conventional construction methods.

stc-value-matrix

Demo – STC Ratings of Walls

Master Bedroom Soundproofing

While 1/2″ drywall is cost-effective, it often leads to marginalized sound attenuation in homes. Fiberglass batting and mineral may yield minimal increases, but they are primarily designed for thermal insulation, and do not have stand-alone STC ratings. For cost-effective soundproofing at home, soundproofing membranes and panels can offer a solution that meets your clients’ needs without exceeding their budget.

Listen below to the difference between walls with STCs from 30-50 for some of the most common residential construction assemblies. For sensitive areas such as Master Bedrooms, Bathrooms, In-Home Studios, and Home Offices consider adding soundproofing layers to further increase attenuation and prevent long-term noise annoyances.

HINT: Stand a few feet back or take a few steps to approximate real-world conditions.

1. Music Coming from Next Bedroom (STC=0) – Played at a standard volume of approximately 75 dBA

 

2. 1/2″ Drywall Each Side (ES) (STC=30)

 

3. 1/2″ Drywall Each Side (ES) with R13 Fiberglass Batting (STC=32) – Acceptable in Many Non-Sensitive Areas of the Home

 

4. 1/2″ Drywall ES with Mineral Wool (STC=34) – Rarely Acceptable in Custom or Luxury Homes with Sensitive Areas

 

5. 1/2″ Drywall ES with Wall Blokker Membrane (STC=37) – Sometimes Acceptable with Sufficient Background Ambient Noise in Receiving Room

 

6. 1/2″ Drywall ES with Wall Blokker PRO Membrane (STC=41) – Generally Acceptable

 

7. 1/2″ Drywall ES with Wall Blokker PRO Membrane ES (STC=46) – Very Little Sound is Audible

 

8. 7. 1/2″ Drywall ES with Wall Blokker PRO Membrane ES + R13 Fiberglass Batting (STC=48) – Ideal Construction for Luxury Homes in Master Bedrooms, Media Rooms, and Offices