The Folding Wall Puzzle
By: Gary A. Barranger
Photo Note: In the photo of a self-support truss system – which can be installed (as here) below the ceiling, or more importantly above – if we pretend that the lower horizontal silver colored line is your ceiling, then the area between that and the silver-colored line above is what you ought to see when you look above your ceiling if you want maximum sound control. Sadly without that, there may be no sound control at all! A system such as this provides two benefits – support in places where it is not now available or costly, and, it automatically provides a 24" high acoustical baffle. This is available from a number of manufacturers.
Churches everywhere have been investing in folding walls of one type or another for many, many decades. As good stewards of our church's funds, it is incumbent upon us all to make sure that money is well spent and that we actually get value for what we spend.
For many years, I have listened to church committee members, clergy, contractors ask first for a "sound-proof" divider. This does not exist, and so they are told. Then begins a time of questioning on both our parts to try and figure out what they actually need, or may need, and explain to them a few things that will guide them in their decision making.
Here are some simple rules to follow so that you do get what you expect for the money you spend:
1. Get an education about folding walls and acoustics before you start your search.
A good place to start is looking at the websites of the various manufacturers. Do a search for folding walls, folding doors, retractable partitions, accordions, accordion doors, operable panels partitions, etc. This will lead you to three groups: manufacturers; marketers who sell the products of others (generally) over the Internet; and distributors of the manufacturers who should be able to visit your church, take measurements, look above the ceiling for support and provide you with prices for not only the material but also the labor to install it. (That said, our experience has been that an increasing number of churches, with budgetary constraints that we all understand, are installing many of these products, especially the accordions, themselves. If you have a contractor, carpenter or jack-of-all trades in your congregation, you have the potential for installing this product.) All the manufacturer websites have volumes of information for you to use and learn. Some even have videos to help explain their products and how they work.
Next, do another search for the acoustical values of walls. You will find that most interior walls
of buildings are non-insulated and such a wall typically has an STC (sound transmission class) value of 35, whereas when the inside of the wall is filled with insulation, the rating will rise to 41. It is not often that your church's walls will have any rating higher than these.
But, what does that actually mean, and how can I learn to distinguish what I want? In your church, go to the common wall of two classrooms and, with the doors to each closed, speak, play music, etc. and see if someone on the other side hears noise, can distinguish conversation, or is offended enough by this to say "this certainly is not what we want." Then go to the Mens' and Womens' restrooms. Here, assuming that they are back to back, again close the doors and speak or play music to determine how much noise is heard on the other side. Typically, classrooms have non-insulated walls (STC 35) and restrooms will be constructed with insulation (STC 41).
With this newfound knowledge, you can move on to Rule 2.
2. You don't need STCs much higher than these – no matter what someone may tell you.
If a river's highest flood in 200 years has been 25 feet, you can build a damn 35 feet high to control it, but what would be the point of building one 150 feet tall? Overkill!
The hotel downtown with various meeting rooms, amplified sound, and people paying for various functions may need something higher, but you really do not.
3. Sometimes a church will be led to buy a room divider with a much higher STC, have it installed and then discover the conventional drywall walls between classrooms has a much better STC.
In fact, I have heard more than once, "You can hear everything that is being said in the other room!" Don't find yourself in this predicament. After all your study and then listening to folks describe what they are pricing for you and what if will do, why are you dissatisfied with the result? Because the room divider is only one element of the process of providing an acoustical barrier between two halves of a room. You also need to know about and address the flanking paths of noise below, beside and above your opening. To be truthful, unless you are working with construction of a new building, there is little than can be done about sound moving down the classroom walls and past the divider.
So, 2 of the 4 offenders cannot often be effectively dealt with. ASTM, the testing group that sets standards for acoustical tests, says that there should be a break in the floor covering directly under the divider – so, a threshold is not a bad idea. However, many object to its installation for a host of reasons.
That said, we are left with what is actually the worst offender – the area above the ceiling where sound can go freely from one side of the room to the other in far too many instances. Why? Simple – there is nothing to stop it! We find that in more than 50% of cases today of NEW construction an acoustical baffle is neither called for nor detailed, so contractors just don't build one.
This is one thing that you can do with that contractor, carpenter, etc. from your congregation. Build a wall of the same sound rating as the divider (35 or 41) from the track up to the floor or roof above. Even when this may not practical or affordable, you can run a single piece of sheetrock up and then tape the joints. This will greatly improve your net result. Even for dividers that have been installed for 10 years or more, take a moment to lift a ceiling tile, look above and, if nothing is present to block the sound, you have a building committee project for some rainy Saturday morning.
Remember the dam mentioned above – if you build it 150 feet tall, water can still get to the other side if you don't take the damn all the way up the 2 riverbanks!
4. Dividers are available with many finishes: vinyl (typically the entry level finish), vertical ribbed carpet, cloth fabrics, etc. Contrary to popular belief, these have no effect on the acoustical value of the divider.
It's an aesthetic consideration and little more. Accordion doors inherently have some NRC (noise reduction coefficient) value. This measures the amount of sound that hits a wall and is absorbed by it (i.e., doesn't bounce back into your face). Flat paneled operable walls generally have no NRC value unless their faces are perforated and backed with sound absorbing material.
There is one new product on the market called "Acoustical Harmony," which is made of 100% recycled water bottles that has an NRC 0.20, so you can get some NRC benefit, which is important in many smaller classrooms, and be very "Green."
And, after all of this, if you do make the right selections, you can save some "Green!" Good Luck!
Gary A. Barranger is president and co-founder of Barranger & Company, Inc., a Building Specialties supplier located in Richmond, Virginia, where he works with his brother and sister in their family's business, www.barranger.com.