I’m building a shop in the garage adjacent to the bedroom. I’m going to build another 2X4X25′ L and 11’T wall on the inside of the garage for a subpanel, and some other utilities to go into. Plus I need to try and minimize the noise going through the wall. So far I plan to space the wall 1″ away from the existing wall, stuff it with fiberglass batts(R25?), sheet it with 1/2″ drywall, and I was thinking of 1/2″ foam between the studs and the drywall. I’m not up on sound deadening. Any suggestions? This isn’t a full production shop so I think this might be enough.
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This subject seems to come up every couple of weeks, so if you do a search (assuming it is working) you should be able to get some extensive ideas. I feel that regular fiberglass bats are not necessarily the best for noise absorption - cellulose would probably be better (several inches of wet sand would probably be the best...) However there are some types of fiberglass bats that are advertised as having sound insulating qualities - perhaps it is coated with something to make it more resilient.
There are various materials such as the old Celotex and other fiberous boards that work pretty well. I used it as the finished wall in one bedroom back before I worked as a fire protection engineer. I now would recommend that you cover it with gypsum board. Perhaps two thicknesses of gyp if you want more isolation. Heavy foam rubber or plastic is used when acoustical isolation is desired with minimal bulk - but the stuff ain't cheap.
Having the shop wall isolated from the house wall, as you have indicated, is a biggie. However, you want to make sure that you don't end up making a solid connection to a beam, rafter, joist, or stud that will bypass your isolating wall and telegraph the sound directly into the house.
You ought to visit the US Gypsum website for their recommendations for constructing sound walls. Also, at a recent building products show there was a booth featuring a sound proofing material (http://www.acoustiblok.com). I haven't visited the site yet but there might be info you could use.
Butch
I converted a basement room into a home entertainment area. I needed a quiet room so I could watch a movie with Dolby 5.1 and not wake up the dead. I used heavy insulation in all interior walls and ceiling. I doubled the drywall full inch. I also used a solid core door. I got the recommendation from a friend that is a drummer. The only thing he suggested that I could not do was allow a dead air space between the room ceiling and the floor from the second story. I did not have enough clearance. It works very well. The only thing you can hear upstairs in the living room is the faint base of the sub-woofer. It makes it kind of nice with the wife goes yelling for you as well! She refers to it as my pout house.
Edited 5/18/2004 3:10 pm ET by bones
Fiberglass thermal insulation does not have enough mass to absorb much sound. There are special fiberglass mats for sound absorbtion. They are quite dense, feel like thick felt matting.
There are many products designed for sound control, such as Homosote board and resilient channels. This site has good discussion. http://www.usg.com/Design_Solutions/2_3_4_acoustictips.asp
I read somewhere that if you use two layers of sheetrock, make them different thicknesses. It has something to do with the cancelling out of sound waves. My husband works the night shift. We have children. This is not a good combination! With our bedroom addition we used sound board under the sheetrock. THe soundboard is like stacks of paper grocery bags compressed together. It really smelled terrible, untill it was covered. We had to plan the light switch boxes and outlet box positions for the thicker wall. The doorway trim needed creative work because of the extra thickness. My husband is very happy with the quiet.