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This question is often asked by developers, architects and contractors – and the short answer is double layers along with sound isolation clips. Here is a more detailed response.
It can be very hard to control installation quality when using single-layer systems. Leaks can occur, leading to sound flanking. Flanking is the industry term for sound leaking around the perimeter and joins of a ceiling. To minimize the dangers of faulty installation – such as large perimeter gaps, open joints between drywall, and bad jointing – you can use two layers of drywall with staggered joins.
Here’s more. Sound travels through the wall or ceiling assembly, causing vibrations. When you add mass to the ceiling, as you do with dual layers of drywall, you’ve created a heavier barrier that is more resistant to vibration – therefore, to sound. Plus, if you would like to achieve the two-hour fire rating that is preferred by the Underwriters Laboratory and sought after in some applications, using two layers of drywall is a economical solution.
And, here’s one more reason! Gypsum companies strive to make their drywall as light as possible. So, they experience with formulas to create a less dense board. The problem is that these boards lead to bad acoustics, poor soundproofing and a lower fire rating. Plus, these boards are not keeping up with the evolving testing standards created by organizations such as ASTM International, the organization that does the following:
“Working across borders, disciplines and industries we harness the expertise of over 30,000 members to create consensus and improve performance in manufacturing and materials, products and processes, systems and service.” Pabco Gypsum states.
“A type X drywall panel today is lighter than one produced when some of these tests were conducted. Any assembly tested before any of these changes were implemented could result in relying on inflated expectations and could be misleading. Simply put, if a standard wall assembly achieved an STC 51 rating in 1968 and were sent back to laboratories for testing today, it would not achieve an STC rating above 46. So what may have been acceptable by the building code in the 1960s may not meet code today even though these assemblies are still presented in current industry handbooks.” (http://www.pabcogypsum.com/sites/default/files/QuietRock_Acoustic_Fire_Design_Guide.pdf )
Resilmount Provides Sound Isolation Solutions
Clearly, there are problems with lighter weight drywall boards and with single layering of drywall. Fortunately, Resilmount® is a top specialist in sound isolation systems including metal furring channels and sound isolation clips that break the path of sound.
Are you ready to tackle your toughest noise control engineering challenges? You can find our catalog here and fill out this form to receive our Technical Manual that includes assemblies both sound and fire rated. Have questions? Please:
- Contact us online with your questions
- Email firstname.lastname@example.org today
- Call us toll-free at 800.675.8023