Building Quieter: Achieving the fine line between aesthetics and acoustics in wall and ceiling specifications

by Katie Daniel | October 5, 2015 11:16 am

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by David Ingersoll
Design/construction teams are constantly balancing the desire for a high-quality look and feel with adherence to acoustical requirements and project budgets. This is especially true when it comes to wall and ceiling choices. Whether selecting from basic wall and ceiling panels or custom woodwork, noise is a primary consideration—no matter how it looks, it has to perform.

As with any construction project, it is most cost-effective to create an acoustically correct wall and ceiling system during the planning stage, rather than address the problem later. By being more informed upfront, construction teams and specifiers can eliminate guesswork and choose a solution that performs properly by delivering acoustically correct wall and ceiling panels in any environment.

Understanding NRC and STC
Many project teams neglect critical ratings that denote noise control performance. The noise reduction coefficient (NRC) and sound transmission class (STC) play important roles in guiding how well a new space will perform, acoustically speaking.

While NRC and STC are often lumped together in a generic category of noise reduction, these ratings serve dramatically different purposes. NRC boils down to the amount of energy absorbed when a sound wave comes into contact with a surface—in this instance, a wall or ceiling finish. By giving early thought to the room’s finishes and surfaces, the acoustical engineers can ‘tune’ the room for optimal performance based on the end user’s needs.

When an acoustical engineer evaluates NRC, he or she is looking at the reverberation time or the RT60 of the space. Reverberation time represents how long a sound lasts within a given space before it dissipates, or specifically how long it takes a signal or a sound to drop 60dB. A decibel (dB) is a logarithmic unit used to express the ratio between two values of a physical quantity, often power or intensity. When measuring reverberations, the standardized testing method relies on a 60db range for the purpose of achieving a baseline. Construction teams should determine the appropriate reverberation time for each room or section of a building. For example, a hotel lobby with a broad open area might be admissible to a higher reverberation, whereas a library demands a lower reverberation level.

Throughout typical construction projects, there are spaces fitting each category of NRC tolerances. For example, homes, libraries, and corporate offices have lower limits, while lobbies, auditoriums and theaters have higher ones. The bottom line is, the room needs to perform well and to achieve this state, the acoustics must be ‘tuned.’ If a conversation cannot be held, or if announcements over a public address system sound muddled, the space in question has a reverberation problem. When you can hear too much—like the confidential conversation happening in the next room—there is a problem with STC.

STC is a measuring stick for how much sound is blocked out of a space. Project teams may choose noise-blocking materials for apartment or office settings, where it is essential to control noise from room to room.

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Planning for performance and style
Of course, as much as noise control is important, most building owners and facility teams are under equal pressure to make the space look good. While the aesthetics can drive the price tag higher, advanced planning can enable acoustical teams to achieve a pleasing space both visually and auditorily.

Major headaches can be avoided when construction teams work in tandem with acoustical engineers from the beginning of the planning process. Early involvement can also reduce labor rates by allowing general contractors to layer in acoustical solutions during the initial wall and ceiling installation, rather than hiring costly specialty contractors to install acoustical solutions after the fact.

If beauty is important, project teams can build in architectural treatments around sound control elements in the design phase, rather than ending up with generic, rectangular tiles that simply control noise without a custom look. Understanding each component of wall and ceiling specifications, and its role in solving acoustical challenges, can help construction and design teams specify customized finishes for a better price with lower labor costs.

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Wall panels
Fabric-wrapped acoustical wall panels are ideal for areas that require noise reduction, such as schools, gymnasiums, corridors, churches, airports, restaurants, and offices. The choice of proper wall panels depends on the specifications for the project. There are wall panel options for everything from economical multi-purpose absorber panels to models featuring impact resistance for absorption and durability, along with composite options including both superior absorption and noise-blocking performance.

To achieve a custom look, there are also wood wall panels available in various finishes. These systems feature veneered acoustical treatments with perforations or grooves able to achieve a variety of NRC levels.

Ceiling tiles
Ceiling tiles are designed to acoustically treat and soundproof interior wall and ceiling spaces with reverberation problems. In cases where aesthetics are important, ceiling tiles can deliver customized options for satisfying both acoustical and design requirements, including cloth and wood finishes.

Acoustic ceiling tiles are available in many different facing and edge details—with standard or custom sizes—backed by barriers meeting high STC and NRC requirements. Standard and custom wood ceiling panels feature a genuine wood veneer on a medium-density fiberboard (MDF) substrate with a generic balancing veneer on the back side to help achieve a custom look without the custom price tag.

Floor underlayments
Acoustical floor underlayments are designed to mitigate foot fall or foot step noise between the floor and ceiling assembly. The higher-quality underlayments are typically designed and marketed by application as different floorcoverings require different underlayment needs. There are glue-down and floating floor options, and the composition of these product ranges from rubber to cork to substrates made up of recycled content. Acoustical floor underlayment’s can have the added value of insulation and can typically carry an R value.

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Sound diffusers
Sound diffusers are perfect for projects requiring a high degree of sound diffusion, such as music rooms, band rooms, or concert halls. They are finely tuned to reflect sound and commonly come in barrel- or pyramid-shaped options. One should choose a diffuser constructed of high-strength, reinforced fiberglass molded into either a one-piece barrel or pyramid shape. When selecting among diffusers, it is important to look for lightweight options that are easy to install and available in different finishes, such as fabric coverings or gel-coat finishes.

Noise barriers
Noise barriers are designed to stop the passage of sound through walls, ceilings, and floors, making them suitable for construction projects involving hotels, classrooms, multi-unit residential buildings, or home theaters. While noise barriers come in a variety of forms, flexible solutions are the most versatile and cost-effective for reducing noise transmission, as they come in an easy to carry and customizable roll.

Before selecting a noise barrier, acoustical testing must be performed to ensure it meets the optimal sound requirements, an important first step when choosing any type of noise barrier—for walls, ceilings, and floors. Solutions with STC ratings up to 31 are available.

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Absorbers
Absorbers come in a several forms to meet a variety of project types. Regardless of the absorber required for the project, all components should meet Class A fire ratings per ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials.

Baffles present the most economical option for addressing reverberation issues, as they are available in a multiple thicknesses and standard sizes. These absorbers can also be easily customized to meet design requirements through custom-specified fabrics or colors.

Ceiling clouds are another absorber type ideal for reducing noise intrusion in ceiling areas. They can be suspended horizontally with eyehooks or in a T-grid attachment that may be secured in the field or at the factory before shipment. Like baffles, ceiling clouds can be customized with various fabric, color, and edging choices.

Catenary banners are a popular absorber solution for areas that have a large, open space such as gymnasiums and multi-purpose rooms. These products can be easily installed on ceilings with grommets, and are available in various thicknesses and lengths to meet the requirements of different project types.

Real-world results
A prime example of advanced planning delivering superior acoustical and aesthetic results is a wood ceiling panel installation at the Austin Chinese Church in Austin, Texas. When church leaders decided to renovate the 318-m² (3420-sf) worship facility, there were several goals, including an improved acoustical experience.

As is often the case in worship facilities, the extreme height and angles of the ceiling created a less than desirable sound quality for congregants. The ceiling panel solution for this project had to address these acoustical problems, as well as reflect the design team’s goals of creating a welcoming environment and account for the extreme variations in temperature and humidity that is typical for the region.

The project utilized linear ceiling panels that combined an aesthetically pleasing birch veneer finish with excellent acoustical values. The wood panels finish ensured longevity, providing the church with a solution engineered to their specifications and designed to withstand multiple years of use.

The schedule for the project was tight. As is typical with religious facility projects, scheduling was contingent on the delivery and installation of the church pews. All ceiling installation needed to be completed by a hard date to accommodate this phase of the project, requiring the teams to build around the specifications of the ceiling panels instead of adding them in later. By adopting a coordinated approach between the design, installation, and acoustical teams, the ceiling installation was completed on time and within the owner’s projected budget.

Manufacturing
The manufacturing process for the wood ceiling panels combined both solid wood and veneered MDF to make panels incorporating different blade sizes and spacing. Due to the size of the project, multiple logs were sourced and sorted by the master veneer-maker to ensure optimized log-to-
log consistency.

There were many panel groupings at different heights in the Austin Chinese Church, which made perfecting the layout of the ceiling critical. The acoustical team specified a 17-mm (11/16-in.) wide by 38-mm (11/4-in.) high blade with six blades per panel. After slicing, the veneer was laid up by hand with particular attention to color, grain structure, and overall size. While pre-manufactured veneer or laminate would have shortened the lead-time for the products, the made-to-order manufacturing of the veneer kept the cost down and maximized quality control.

To provide the owner with a ceiling that performed as well as it looked, the backside of the panels were covered with an acoustic textile combined with a generous percentage of open area provided by the blade spacing.

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Installation
Since there were many panel groupings, and at different heights, the acoustical engineering team created complex shop drawings to ensure proper layout. These drawings detailed a combination of reflected ceiling plans and sections through the multiple planes and levels of the ceiling. The installation plan also dictated design and implementation of the panel terminations at specific distances from the wall and/or bulkheads, as well as the incorporation of the various lighting, HVAC, and fire protection systems.

Finally, particular attention was paid to the extreme heights of the space and the variations in temperature and humidity that would occur throughout the year. Creating panels to withstand these conditions ensured a solid installation, intended to offer beauty and quality for years to come.

The custom construction and installation of the acoustical wood ceiling panels resulted in a 0.75 NRC rating per ASTM C423, Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method. Wood veneer panels also delivered acoustical performance in a cost-friendly package.

Dave Ingersoll has 15 years of experience in the soundproofing and noise control industry. He began his career with Acoustical Solutions, and in his role as director of business development, he works with Sound Seal’s network of distributors and representatives to grow and expand the Architectural and WoodTrends lines of acoustical products. Ingersoll can be reached at dingersoll@soundseal.com[8].

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