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Folding Walls and Doors
By: Gary A. Barranger

Let’s first look at your initial steps. Before calling anyone, collect some information about the particular room that is to be divided.  Make sure you know where the room is, and particularly what floor it is on…or, is it down in the basement? What is the construction of the room (walls, floor covering, ceiling) and, most importantly, what is above the ceiling that you can hang and support a divider from? Room dividers can become very heavy as you increase their ability to block sound and as you look at different finishes, so know what’s up there. Next, get an idea of the dimensions of the room. If you don’t have a tape measure with you, it is still possible to provide others with an idea of size.

Count the ceiling tiles. Most are either 2 x 2 or 2 x 4, so 10 (24”) tiles means your room is going to be pretty close to 20’ wide

Look at the doors into the room. Most doors are either 6’-8” or 7’ so if it looks like there is only a foot above the door to the ceiling, then you have a pretty good idea of room height. And, the room must be close to 10’ high if it looks like there’s a yard of space above.

If you’ve had problems with things falling on the floor in that room and rolling across it, then your floor isn’t level, and the people you are asking about providing a divider will need to know that.

Next, here are some things about dividers that you need to know:

There is no such thing as a “sound-proof” partition. 
The salesman you talk to will know from the start that you know little or nothing about the subject if you ask for such.  Dividers of all types (accordion, operable folding, rotating, descending, manual, electric, covered in vinyl, or in carpet, etc.) are designed to stop a certain amount of sound from going from one side to another.  A divider with an STC (Sound Transmission Class) rating of 35 will stop roughly 35 decibels of sound from going through a room division. So, if you are going to be generating 50 decibels of sound (average classroom) on one side of a room, then only about 15 decibels should be heard on the other side, which is perfectly acceptable. Most walls in a church are STC 35-42, which is the range of standard drywall constructions. And, if your walls are block, 4” to 6” painted CMU walls have STC of 41-43.

Don’t get talked into buying too high an acoustical rating. 
It’s expensive, it’s heavy (you need increased weight and mass to get increasingly higher STC ratings, so you may need to actually build a structure to carry the weight), but, more importantly, in the end there may be little or no benefit. Why are people dissatisfied with their dividers? Most people don’t understand sound. Sound, like water, will follow the path of least resistance, so you need to look at all the perimeters of an opening and determine if sound is going to spill around the new divider and defeat its purpose. 

The ASTM (American Society for Testing Materials) has developed guidelines for the construction of openings for folding walls and door (E557), which tell us to put a break in the floor covering of a room beneath the divider.  Many find this aesthetically offensive.  Also put vertical control joints in the walls at both ends of an opening (not real practical in an existing building; expensive and, like the floor condition, not all that attractive).  Last, you need to build an acoustical baffle that extends from the top of the track to the floor or roof above (expensive). 

So, if sound is going to bleed around the divider, where do we go? In most church settings, dividers with STC ratings around 35 are well-received. They are similar to most walls in the building except those around the bathrooms, so you are not giving up anything, and it’s okay to look at slightly higher (39, 40, 41), but at some point thereafter most of the extra money you are spending for the increased sound rating is just a waste of that money.

Understand that “finishes” have no impact on acoustics. 
Carpet or cloth are going to yield no better STC rating than vinyl. Some finishes may give you some additional control of sound reverberating within the room (i.e., sound – your voice – bouncing back at you) and in rooms that are small, and destined to be smaller with the divider, this can be important. 

Accordion doors, by the nature of their construction, inherently have some NRC (noise reduction coefficient), so they will help deal with the echo within the room better than a flat paneled product, such as an operable folding wall. There also are acoustical fabrics (some that are very “Green” as they are made of 100% recycled water bottles) and perforation treatments of operable folding wall panels that can provide certain levels of NRC. But, be careful. Color charts for some fabrics and carpets say that they have high NRC ratings. This is not actually true. The referenced ratings are the result of the material acting as the covering for a “sound–soak’ panel, etc.  Always ask to see the test papers to make sure that you are not actually getting results of two different products instead of the one you think you are buying. It’s important to always ask for complete, unedited, STC test report and please read it to make sure what you are buying is actually what was tested. A product tested at 7.45 lbs. psf will not yield the same STC as one that weighs only 4.0 and products with 1/2” floor clearance will not function in your church as you pull it across a room.

Know the lingo.
In construction, many objects have different names. Regional, professional, industrial terms for the very same product are not uncommon. So, folding walls and doors are broken down as follows:

Products that open and close like an accordion musical instrument  are commonly referred to as accordion doors but can also be referred to as retractable, folding, collapsible, folding doors, etc.

Products that are made of nominally 48” wide panels (2-1/2” to 4-1/2” thick) that move across a room one, two, sometimes three, and/or as a single continuous unit are most commonly known as operable walls but can also be called airwalls (especially if you have a background in the hospitality industry), folding walls, operable folding walls, relocatable walls, etc.

Panels that move one at a time are “individual” or “omni,” those that move two at a time are “pairs,” and those that move all at once at “continuously hinged” or “trains.” “Trains” can be either manual or electric, but this really becomes a expensive proposition.

There is also a new generation of dividers that spin (allowing expensive equipment to be shared between rooms), that descend from the ceiling (must be electric and has a myriad of safety features), and that are made of primarily glass (options include non-acoustical space dividers, trimless, trimmed of metal, framed in wood) and acoustically rated.  You may wish to explore these as a possible selection, but be advised they are generally more expensive than traditional folding walls and doors.

And so, it’s now time to call not one, not two but three or more distributors of folding walls and doors. Tell them who and where you are, what type of room and where is to be divided, what the dimensions are (exact or approximate), that you want a moderate level of sound control, and you are looking for a particular finish – perhaps with some options for others. 

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.

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