There are many ways to try to slow down the sound transmission between rooms. Before you decide on a strategy you need to know how much of a reduction is needed. For most residential single family homes the main goal is just making the rooms a bit quieter than if you only had two layers of 1/2″ sheetrock between the rooms. In my days of working for a production builder we used 1/2″ sheetrock and hollow core doors. Let me tell you that didn’t reduce the sound much between rooms. If Johnny has his stereo blasting in his bedroom, his sister in the next room over was almost hearing that stereo full blast.
So, how can we cut that down? #1 use 5/8″ sheetrock instead of 1/2″ rock. When my clients want smooth drywall instead of the usual texture you see in Texas homes believe it or not that extra 1/4″ of sheetrock (accounting for both sides of the wall) makes a huge difference. Plus the 5/8″ rock is stiffer and spans small imperfections in the framing better. #2 use solid core doors, much better for sound transmission. #3 the easiest and cheapest method to go to the next level of sound proofing is to use fiberglass batts. This helps some but isn’t a huge reduction.
I’m going to show you in this video my favorite way to reduce the noise but not spend too much. There are definitely ways to reduce sound transmission even more, but those methods of course cost a bit more…
That Homosote you saw is a recycled paper product that my local BMC lumberyard stocks. It is around $20/sheet. Here’s some photo’s of the finished wall on both sides.
Last note here, don’t forget that when you create a conditioned attic space with spray foam that you’ve got sound transmitting easier through the attic than when you had 13″ of fiberglass on your ceiling. You need to tell you clients to expect some noise from the attic unless you take other preventative measures. -Matt Risinger