The goal with isolating room-to-room sound bleed through a common wall assembly between two adjoining rooms in a hotel is twofold. First, your goal should be to disconnect how the wall is assembled, and second, line it with more density. The treatment is fairly straight forward and can eliminate up to 90% of the noise that would otherwise bleed through your wall.
Step 1: Disconnection
Imagine a string pulled tight between two coffee cans. Vibrations carry your voice back and forth through the string, to become air born on either end. If you snipped the string with a scissors, the vibration collapses and so does the home made telephone. The frame in a wall connecting two rooms together serves the same function as the string. Your goal is to first disconnect the rooms and force the collapse of the transmitting vibration.
Room disconnection takes place with a channel system for existing/finished walls, or with double wall or staggered stud wall assembly for new construction. Any of the techniques will force the collapse of the wave and help protect the privacy of your guests. Channel systems could be resilient channels, hat channels or simple furring strips that are placed horizontally up over the finished surface of your existing wall to create a dead air gap. If your wall is not yet built, a double wall or staggered stud assembly will negate your need for the channels. A double wall is just what is sounds like, frame two walls side-by-side. A staggered stud assembly sounds complicated, but it really isn’t. Start with a 2’x6’ floor plate, and set your 2’x4’ studs in place so that studs 1,3,5,7,9, etc run flush with Room A, while studs 2,4,6,8, 10, etc run flush with the opposite side of the floor plate to support the wall for Room B. In any of these cases, disconnection forces sound wave to collapse inside the cavity of your assembly….but you’re not done.
Step 2: Add density
Next, think of a tuning fork, a guitar string or the top of a wine glass. With any of these mediums, if they are allowed to vibrate, they will produce sound. But if you place the palm of your hand on any of them, the mass of your touch kills the vibrations, and therefore the sound dies with it. The goal with your common wall is to keep it from resonating like a tuning fork. By simply adding mass to the surface, you impede its ability to accept vibration. If a wall can’t vibrate, it can’t accept or transmit sound.
Adding mass to a common wall assembly is easy. NetWell Noise Control, of Minneapolis, MN, has been shipping a material called dB-Bloc to project sites around the world for 20 years. This is a thin, dense membrane that can easily be stapled up to a common wall assembly to impede sound vibrations. The material is ordered in 54” x 30’ rolls weighing 150 pounds, but measures just 1/8” thick. Where to layer dB- Bloc in your assembly depends on your starting point. This is not a finished surface material, but a material layered behind a final drywall layer. For more information on dB-Bloc and how to properly install it, call NetWell’s help desk at 1-800-638-9355 or visit them online at www.controlnoise.com.
By properly layering density into your wall assembly, and disconnecting the structure of the wall, two adjoining hotel rooms can experience up to a 90% elimination of sound bleed. Please note that there is no cure to the bleed, only better control over the environment. Sound will always carry through floor or ceiling vibrations, and through flanking paths such as ventilation, plumbing and electrical systems. Care should be given to minimize cutouts in common surfaces to help prevent the decay in your results. Good luck!