Dance Studio Next to Office Space
Recently, I was asked to meet a few potential clients at an office building in a neighboring city. It was explained to me that a dance studio and an office shared a common wall. I have worked on similar situations in the past, and it is always a bit scary – simply due to the drastically different uses of the spaces. The problem that existed is that when the building owner was showing a few potential office renters the space, the dance studio was having a class. The sound transmission was an instant turn -off to a potential renter – and rightfully so.
99% of the time, the main problem why dance studios sharing a common wall with any other type of business is not a good idea, is because on one side of the wall, you have not only dance music which is an acoustical beast in-and-of itself, but you have moving, jumping people, and in this case, screaming teenage girls. The bass waves from modern dance music will usually make its way through a structure extremely easily. On the other side of the wall, you have a relatively quiet space. People who are working in front of a computer or on the phone with clients do not need to hear the thump-thump of muted dance music.
Despite my reservations relating to the drastically different uses of the space, I decided to visit the location and see just how bad the problem was. I will do my best to paint a visual picture of the room, so you have an idea of just what the tenants are dealing with. The building is a pre-cast concrete structure with a metal roof deck and concrete floors. Very similar to every other building in every other industrial park out there. The building was, of course, sectioned off for multiple tenant uses. The common walls (and I’m 80% assuming here) were single, metal stud construction, filled with standard fiberglass insulation.
When I got to the space and started discussing the problem with one of the business owners in the dance studio, he showed me the room and the acoustical situation was about as bad as it could get. The first and most significant problem was that the sheet rock on the common wall stopped a few inches short of the metal roof deck. The gap between the rock and the deck was filled with very light density foam cut into strips. From an acoustical standpoint, here was nothing there but a 2″ – 4″ air gap connecting the two spaces. Not good, and obviously a good place to start. As I have explained in other blogs, a 1% air gap in a sound barrier can leak up to 30% of the sound from one side of the wall to the other.
Not only did the room have a tremendous sound leak over the top of the wall, the room was nearly a perfect cube. The measurements were 25′ wide, 25′ deep, and 16′ tall. The floor was concrete, the walls were painted sheet rock, and the ceiling was painted metal roof decking. With two people standing in the room having a normal conversation, the echo and reverberation were incredible. Once the music was turned on, it got even worse. It was explained to me that once the music and instruction began, the music volume kept going up and up and up – simply so things could be understood. This is commonly called the cocktail party effect. The noise level in the room steadily increases because people have to talk louder to be heard. After a few minutes, everyone is screaming at each other simply to be understood, and the acoustical energy in the room increases exponentially.
The last, and most audible problem with the building was the low frequency sound transmission that was leaking in to the offices. Lower frequencies are almost always the most audible simply due to the type of wave that makes up the sound. When we had the music on in the studio and went over to the office, I put my hand against the common wall and could feel the sheet rock resonating. Because the stereo in the dance room was backed up to the common wall, the sub-woofer was energizing the structure which became VERY apparent when I touched the wall. Even at a low volume, the wall was still vibrating. This is obviously a problem.
The recommended solution:
My recommended solution to the customer was a three part process. To have any affect on the space, they are more than likely going to have to go through all three steps, but I suggested that they proceed as follows:
The first step is going to have to be taking the foam out of the air gap along the roof and replace it with expanding foam as well as a non-hardening sealant. I also suggested sealing up every other penetration that they can find. There are fire-suppression pipes and electrical lines that penetrate the wall as well – that all need to be sealed as tight as possible. If these air gaps are not addressed, any other acoustical treatment is going to be short-circuited very quickly. Very commonly, people use our Pro Series Acoustical Sealant to do just this.
The second step that I recommended was to install 280 square feet, or 30 2′ x 4′ x 2′ thick panels of Echo Eliminator B.A.C. (Bonded Acoustical Cotton) on the walls of the studio. This will bring the reverberation time (echo) down to a reasonable level so that the stereo does not have to be turned up to full volume to be understood. If the sound level of the room is lower, the sound waves in the room are not as strong. The weaker the sound waves are in the room, the harder it becomes for them to make it through the wall. The Echo Eliminator panels, having an NRC of 1.15 are some of the most cost effective acoustical panels on the market.
The last step for treating the space is to “float” a new wall on the side of the room adjacent the office. If the finished wall surface does not have any hard surface contact with the structure, it is then allowed to vibrate slightly and turn the airborne sound wave, which is basically a wave of energy in the air, into heat energy by vibrating or moving something. The RSIC-1 Clips, along with a standard 22 gauge Hat/Resilient channel and one layer of 5/8″ sheet rock and one layer of 1/2″ sheet rock, make up one of the most cost effective ways to “soundproof” a room.