Some tips on what works and what causes problems:
The very best product to reduce reverberation in a space is fiberglass – period. For those that say what about Tectum; 1” of Tectum type A mounting (flat to the wall) has an NRC .40 but with furring and fiberglass (Finale panel) behind the 1” panel the NRC is .80. Tectum has the high durability that other panels may not offer which is why you see it in school gyms across the country.
Let’s look at the traditional fabric wrapped fiberglass sound panel. There are ways to make this go smoother and there are things that will make everyone crazy. I would like to avoid crazy as much as possible so I thought I would share some things I’ve learned.
A 1” thickness is usually enough, 1 ½” is more expensive than 2” – has something to do with the way the fiberglass comes
Picking fabric – this is important for several reasons.
· The fabric has to be acoustically transparent or it is a waste of time. For a good article on fabric selection check out: http://www.soundseal.com/soundquality/2011-fabric-document.pdf.
· When deciding on the size of the panels keep in mind the width of the fabric, don’t draw panels wider than the fabric or they will have to be split. To help understand the size, look at the width of fabric. Let’s say it’s 54” wide if you are using a 1” panel then you need to deduct 2” for that then another 6” to allow for wrapping the back of the panel. Now the 54” wide fabric is down to approximately 46” to 48”.
· Fabric availability is critical as well, some are readily available and some will have a 12-15 week lead time. This can cause havoc with schedules. If picking a fabric with a long lead time you can elect to give the manufacturer approval to purchase a set quantity before the walls are built. The risk with this approach is that if it’s too much you are stuck paying for it, if it’s not enough then it will take forever to get the rest and it may not be the same lot.
· Keep in mind an equal number and sizes of panels in one fabric will be less expensive than if they are five different colors. Colors are fine; just make sure everyone knows about them up front. Changing that after the bid will cost.
Panel layout and why it matters:
· If you design sound panels to go floor to ceiling, wall to wall, the order cannot be placed until the wall is built and measured. The fabric isn’t ordered until these dimensions are measured. This can result in a schedule crunch. The simplest way to avoid that is to design island panels – a set size independent of the exact wall construction.
· Using a stretch type of system will also help with the schedule on full wall panels but may not be as readily available depending on installers in your market.
Edges and attachment:
· I always recommend hardened edges; think they hold up better during the installation process. Square edge panels are the least noticeable joint but also can call attention if the alignment is off slightly. One of the most effective designs I’ve seen is using 2” panels with a 1” gap between them – looks very sharp.
· Two part clips versus impaling clips – I often hear the reasoning for two part clips as “we want to be able to take them off”. Here is the drawback to that thought – first of all no one ever actually takes them off anyway, and you can take a panel off an impaling clip as easily as a two part clip. Just reposition the impaling clip and put the panel back up. If you do use two part clips a couple of things to be aware of – you can’t use them on panels that meet a bulkhead. You have to have room to lift the panel up at least ¾” to engage the clip on the wall. Two part clips will add slightly to the overall thickness so don’t mix the two methods if you don’t have to. Then there is the fact that glue is used on impaling clips where they meet the panel, but often glue is also used between the two-part clips to keep them solid – those won’t come off.
How many panels do I need?
That really is the toughest question but there are some basic rules you can follow. If the budget is tight and you can only do a limited amount put them on adjacent walls, not opposite walls. Getting something on the ceiling may be key; we’ll talk about options next time. I’m sure there are many terrific programs out there as well as knowledgeable reps that can help. One of the free programs I use is by Armstrong ceilings: http://www.armstrong.com/commceilingsna/article21088.html?intcid=homepagehttp://www.armstrong.com/commceilingsna/article21088.html?intcid=homepage
In case the link doesn’t work go to Armstrong commercial ceilings and look under Selection Tools, Improve Speech Intelligibility. The thing I like about this is that it lets you allow for more than one product on the wall and you can go back and forth to see what effect the product selection has on the reverberation time. It will give you a square footage to shoot for at least.
For the best outcome with acoustical wall panels – keep it simple please.
Overall good advice on architectural acoustics. I take exception, however, to your statement, "The very best product to reduce reverberation in a space is fiberglass – period." For example, perforated metal panels can reduce reverberation time two ways: 1. Used as a suspended ceiling, perforated panels increase the acoustical volume of a room - one of the factors in reverb calculations. The other is that perforated panels, mounted 12 to 16 inches from a solid surface, increase noise reduction. The air space behind the panels acts as a viscous medium to absorb noise energy.
ReplyDeleteNothing wrong with fabric wrapped fiberglass -- there is a place for all kinds of products.
You certainly are right about metal panels however to increase the efficiency of them they are usually backed with fiberglass. Granted it's wrapped in a thin black poly but it still increases the NRC. That is why I say fiberglass is the go to for NRC.
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