April 2012: The Right Design the First Time


What project have you been working on lately? Whether you’re designing a multi-family building, educational facility, healthcare institution, or theater, there’s a good chance you’ll be concerned with keeping sound either in or out. Project delays, re-designs, and retrofits are costly and time consuming, so why not do it right the first time? Continue reading for some examples of why it really pays off to invest in the right design the first time.

An important factor in developing the right design is having realistic expectations. We recently tested three operable partitions that the client expected to earn Noise Isolation Class (NIC) ratings of NIC-46 based on the manufacturer’s data. From our experience we knew to advise them that NIC-40 was a more realistic expectation. As it turned out, the partitions only measured NIC-30, 33, and 37. We identified some installation flaws that

Photos by Sharon Ho, Metropolitan Acoustics

allowed sound to pass through gaps where tight seals should have been, and once readjustments were made their ratings improved to NIC-39, 39, and 40. Fortunately, this was still appropriate for their purposes, but would not have been if a moderate to high level of speech privacy was required. If that was the case, fixed partitions would have been more appropriate.

Another common issue is sound transmission between vertical units of a multi-family building through floor-ceiling assemblies. In most cases, the tenants have usually moved in before a sound problem has been identified. This adds to a long list of expensive and time-consuming details that will need to be dealt with before the problem is resolved.

We recently worked on two luxury, multi-family buildings where sound transmission between units was an issue; both were failing to meet minimum code requirements. In Case 1, our recommendations were implemented, and re-testing of the new assembly proved to be successful and satisfactory. Case closed. In Case 2, however, the original assembly that we warned against was built, and the tenants were complaining. We were brought in three times over the course of one month to test three different variations of the same, poor assembly. Each time the results failed to meet “luxury” requirements, and even minimum building code, just as we expected. In this case, our recommendations have been ignored, and this development is still struggling to resolve the issue.

Comic from The New Yorker

While we appreciate the business, there’s no reason to test, rebuild, and re-test variations of the same, poor assembly only to be left with the same, disappointing numbers. We’ve seen the same thing happen with noisy mechanical systems (see our February newsletter here). In addition to the 20+ years of knowledge and experience we have, we also consult with various resources and software programs to accurately model our clients’ designs and predict the transmission of sound through them. Let us help you get the right design the first time.

Potential cost of a poor design:

  • Cost for manpower (contractors, consultants)
  • Cost of testing, re-design
  • Lawsuits
  • Cost of going over project budget
  • Cost of replacing noisy, oversized air-handlers
  • Installing vibration isolation treatment for mechanical systems
  • Extra cost of duct silencers, length of duct, lining, lagging
  • Relocating pipes, ducts, air terminal devices, sprinklers, lighting
  • Reapplying finishes
  • Reinstalling/adjusting cabinets, counter tops
  • Relocation of tenants
  • Broken leases
  • Project delays
  • Delayed grand openings
  • Damage to reputation
May 2012: Classroom Technology
March 2012: Cutting Edge