{"id":70362,"date":"2018-09-13T12:06:55","date_gmt":"2018-09-13T16:06:55","guid":{"rendered":"https:\/\/www.constructionspecifier.com\/?p=70362"},"modified":"2018-09-13T12:06:55","modified_gmt":"2018-09-13T16:06:55","slug":"troubleshooting-ineffective-acoustical-assemblies","status":"publish","type":"post","link":"https:\/\/www.constructionspecifier.com\/troubleshooting-ineffective-acoustical-assemblies\/","title":{"rendered":"Troubleshooting ineffective acoustical assemblies"},"content":{"rendered":"

by Jacob Wexler, FDAI<\/strong><\/p>\n

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Photos \u00a9 Legacy Manufacturing<\/em><\/span><\/figcaption><\/figure>\n

A quick read through any hotel\u2019s 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\u2019s sleep while traveling.<\/p>\n

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.<\/p>\n

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\u2019s 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.<\/p>\n

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.<\/p>\n

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.<\/p>\n

Troubleshooting common problems<\/strong>
\nGaps 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).<\/p>\n

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.<\/p>\n

If an acoustical door is not providing sufficient noise control, the very first question to ask is, \u201cWhat type of gasketing was installed?\u201d 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.<\/p>\n

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The strike plate mounting bracket is applied to the frame to allow a door gasket to be applied in conjunction with a door closer.<\/figcaption><\/figure>\n

Another common source of poor acoustical assembly performance is gaps caused by imperfect door alignment. This is a common problem in newly installed gasketing, but can also surface later as buildings shift and settle and doors cycle through changes in temperature and humidity. The best way to ensure consistent, long-term performance is to select acoustical gasketing with adjustable features and the ability to adapt to any future clearance increases. There are models available on the market enabling the restoration of a sound-tight seal using nothing but a screwdriver.<\/p>\n

Beyond gasketing, another area frequently identified as the source of insufficient sound control is the threshold. This is particularly common in situations where the specifier is unsure of the flooring type being utilized in an opening. If an improper selection is made, it can result in a significant amount of space remaining between the bottom of the door and the finished floor, rendering the acoustic door largely ineffective.<\/p>\n

One of the most effective solutions to this problem can be found in concealed automatic door bottoms. Although the configurations of this type of seal are endless, the automatic door bottom is activated in one of two ways. First is the standard opening and closing of the door. If the door is closed, the threshold functions as a latch activating the door bottom and allowing the seal to drop down. When the door is opened, the pin hitting against the stop retracts in the
\ndoor bottom and seal is then concealed into the housing.<\/p>\n

To determine which automatic door bottom mounting option will provide the best acoustical properties, it is imperative to understand the opening. Each opening is different, and every specification writer has their own way of putting together groups of products.<\/p>\n

If a door is specified to include a rabbeted threshold, then a surface-mounted door bottom will be more resistant to noise penetration. The rubber portions of the rabbeted threshold meeting the double seal on an automatic door bottom allows for less leaks. The corner gap where the seal meets the jamb, as any specifier or acoustician knows, is always the biggest issue. The installation of a surface-mounted door bottom in conjunction with a rabbeted saddle mitigates the issue of lost sound in corners.<\/p>\n

The more innovative approach is to have an electronically retracting door bottom that can be activated with a switch\u2014either a keypad, key switch, or a standard momentary switch with no credential requirements. This feature is extremely useful in settings where sound control is particularly crucial, such as law firms and doctor\u2019s offices, and room occupants are also made aware of the feature and its importance.<\/p>\n