WALLS

Unfortunately, the basic walls built in most homes and businesses are simply not dense enough or thick enough to be good barriers to neighboring sound. This page will show you proven methods for adding additional layers of materials to your existing walls to make the most of them. For those of you doing new construction, these tips are applicable as well. The choice of how to retrofit your existing walls, ceiling, etc. is entirely up to you, your ears and your pocketbook.

Existing Walls

First, determine as best you can what the materials are which comprise your existing walls. You hope you find out that you have 2x6 walls, heavily insulated and caulked, floated on SheetBlok, then covered with a layer of ?" gypsum board, a layer of SheetBlok, a layer of ˝" gypsum board and surface treated with Studiofoam.

If so, go directly to Park Place, collect $200 and have dinner at a fancy restaurant. If not, read on. If your problem sounds severe to you and you learn that the existing wall has no insulation in it, it is advisable to install Auralex Mineral Fiber in it by removing the gypsum board and placing the Mineral Fiber between the wall studs. Alternatively, you can look into blowing insulation into the wall with a machine (see your local hardware store for details).

Having done that, the more closely you can retrofit your wall to resemble the one shown in Figure 3.5 above, the better off you will be. You can choose to alter materials or leave off layers, but the performance of the wall may be lessened, so delete or change at your own risk. Naturally, you should use good construction techniques, taping, mudding and caulking seams all the way, making sure to stagger all seams and rotate adjoining layers 90° from each other.

If you determine your problem to be relatively minor, you might be able to get by with as little as adding one (1) more layer of gypsum board. If you previously found out your existing wall is one layer of ˝" gypsum board or plaster on lathe (older homes), add a layer of SheetBlok and then another layer of ?" gypsum board.

Do you want to go to the trouble to fur out from your existing wall to hang your new wall boards on? We think so. It is neither a waste of time nor money and, if you have both, we would encourage it...but with a twist. At least cover the faces of the furring strips with strips of SheetBlok (it is considerably more effective to actually mount a layer of SheetBlok across the faces of the furring strips versus just putting strips of SheetBlok on the furring strips' faces, but it also costs more). Then mount RC8 across the furring strips. Then mount a layer of ?” gypsum board to the channels.

New Construction

If you have the opportunity to build your space taller, allowing for a false/lowered ceiling and giving your studio more cubic space, then you are indeed lucky. If that’s the case, there are a few things to note that you might implement to improve on the wall/ceiling described above.

• You should definitely build a "room within a room," meaning that there is air space and no physical contact between the exterior walls and the new walls of your studio! There is no substitute for doing it this way. You can build just one wall and can add layers to the wall until you are blue in the face and poor as Patty’s pig, but chances are that you will never achieve the level of sound transmission control you will if you go the extra mile and build a room within a room. You know what they say about an ounce of prevention being worth a pound of cure? In the practice of acoustics, an ounce of prevention is worth considerably more than a pound of cure!

• Sound can slip through very tiny gaps (1/32” and smaller) which might seem to you to be insignificant. So it is of extreme importance to construct your place as airtight as humanly possible. When humanly possible is not good enough, StopGap can be of great benefit. The specific gaps we are talking about here are, e.g., the gaps around electrical boxes (remove the outlet and switch plates to find them), underneath door trim, baseboard, crown-molding, around HVAC vents (remove the grilles to find them), and so on. This is all part of the attention to detail we’ve been talking about!

• Never mount electrical boxes or connector panels back to back; always stagger them as shown in the Figure 3.6. Seal the holes your wires go through, or (preferably) run wire through conduit, stuffing foam or insulation in the ends to help seal it. Isolating the conduit from the structure with SheetBlok or hanging it with resilient hangers can really offer some improved isolation. Remember: Sound control is a game of inches.™

• Of course, the less wires and boxes you have poking holes in your walls, the less chances sound has to get through where you do not want it. It may be prettier having all your boxes flush mounted, but there is a lot to be said for surface mounting your phone cables and jacks, audio connector boxes, light switches, etc. Not only does this method yield better isolation, your artsy friends might consider you "retro", "industrial" and just plain "cool." Studiofoam and other Auralex treatments applied to room surfaces can often mask surface-mounted goodies.

• It is always better to keep wires away from each other than in big globs; especially audio, video, data and phone lines that might be in proximity to electrical wires. If wires have to cross, doing so at a right angle lessens the chance of interference occurring. Otherwise, keep all the different typs of wires at least 12” away from each other and use shielded cable wherever possible.

Stringers

There is quite a bit of debate about whether adding “stringers” to your wall, ceiling and floor construction is worth the effort. We believe it is a great benefit to run stringers at uneven intervals between wall studs and floor and ceiling joists before insulating them, as shown in Figure 3.7. This helps tie the whole wall, ceiling, or floor together so it is less likely to move and transmit sound. As Philip Newell has pointed out in many of his books, a stiffer construction will make it less able to vibrate at lower frequencies. Our research is ongoing and we certainly acknowledge that stringers may not be completely applicable to each and every construction. However, in the context of Acoustics 101, we believe it is a necessity. I.e., since the budget for construction is usually tight, we believe stringers to be a very cost-effective way to help maximize isolation.

Figure 3.7 shows stringers mounted between studs or joists. Stringers are short (14˝" normally if your studs/joists are 16" on center) pieces of the same material as your joists that run perpendicular to the joists and are nailed and glued between them in a random, staggered fashion. It might seem like a pain putting them in, but it’s time well spent. We know because we have done it. We let people talk us out of them once and lived to regret it!

Other than the above, the wall construction we generally suggest is shown in Figures 3.1a-b from the section on Floors.