Troubleshooting ineffective acoustical assemblies

by Jacob Wexler, FDAI

Photos © Legacy Manufacturing

A quick read through any hotel’s online reviews will reveal the most common complaint the hospitality industry struggles with is noise. As anyone who has ever stayed in a hotel knows, the sounds of doors slamming at all hours and boisterous hotel guests in hallways are frequent barriers to getting a good night’s sleep while traveling.

Even during daylight hours, noise can be a major problem in facilities hosting business conferences or catered events. From the clattering of dishes in a nearby kitchen to the raucous sounds of an in-house casino or swimming pool, noise can be an incredibly persistent and difficult problem to solve.

Its presence can not only lead to unhappy guests who can immediately broadcast their dissatisfaction to the entire world via social media, but also the inability to control noise in a facility can result in legal troubles. If a room’s occupants can hear outside noise, then passersby can overhear what is being said inside the room, meaning potentially sensitive information could be inadvertently disclosed and result in breach-of-privacy lawsuits.

However, hotels are not the only buildings suffering from noise pollution. Providing effective sound control is unquestionably one of the most persistent challenges for any type of facility from office buildings and schools to hospitals and law firms. When installed door assemblies fail to deliver the specified level of sound control, both the job and expense of correcting the problem generally fall to the contractors and the distributors responsible for the construction and components. In extreme cases, failure to achieve adequate acoustic control could, ultimately, result in legal liability for specifiers who do not choose the appropriate products to prevent sound transmission.

To minimize both the financial risk and potential liability of ineffective sound control, it is vital to understand acoustics and its implications for door assemblies. Ideally, acoustical engineers will be consulted, particularly for high-risk or high-performance sound challenges.

Troubleshooting common problems
Gaps equal noise and the size of the gap has no bearing on the amount of noise passing through it. Sound waves will travel through any opening with very little loss, so although the amount of air flowing through a gap increases in proportion with the size of the gap, the size of the gap in a sound barrier does not matter. Any unsealed gaps and clearances in door assemblies effectively cancel out the noise reduction benefits of even the highest-rated acoustic doors (Figure 1).

Going back to the earlier example of hotel rooms, the amount of noise passing through a 25-mm (1-in.) gap under the door is roughly the same as having the door open. This is why when a guest is startled awake at 3 a.m. to the sound of someone having a conversation in the hotel hallway, it sounds as though they are standing in the room.

If an acoustical door is not providing sufficient noise control, the very first question to ask is, “What type of gasketing was installed?” In the majority of cases, the source of the problem can be traced back to either poor quality or insufficient acoustical gasketing. For any acoustical assembly to be effective, its gasketing must form a complete, uninterrupted, airtight seal around the head, jamb, and sill. To achieve uninterrupted contact, the gasketing must be installed on the same side of the door and frame. Proper performance also depends on maintaining good surface contact between the gasket and the door edge or frame. This can usually be achieved using compression seals.

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