In most homes, the garage is the largest open space available. As such, it can be used for practicing and rehearsing with musical instrument, installing and operating power tools and locating appliances such as the washer and dryer. Soundproofing the garage is often a practical necessity not only for keeping down the noise you make but also to prevent any outside noise from coming in.
Soundproofing the Walls
An effective soundproofing material is common fibreglass insulation added to the walls for extra thickness. Anechoic barriers (triangle-shaped pieces) placed over the fibreglass will scatter and redirect sound from exiting the area. Another material just as effective but more difficult to manage is goose feathers applied in a layer over the walls and secured with wire mesh. This method is recommended only if the occupant is allergic or has a reaction to fibreglass.
Soundproofing the Ceiling
Adding sound insulation to the ceiling may be easier to do from the attic space above the garage. Add more fibreglass insulation and also foam panels over the garage area. If this is not possible--if an occupied room is over the garage, for example--attaching the insulation to the ceiling is the only option. Add as much anechoic obstacles to the ceiling as possible. This will reduce echoing and keep more sound in the room.
Soundproofing the Floor
Most garage floors are solid concrete slab. As such, little or no sound will exit this direction. If the floor is dirt or gravel, however, consider building a false floor of plywood and 2-by-4 bracing. The floor needs to be only a few inches high. Insert fibreglass or fill the space under the flooring with soil or sand.
Soundproofing the Doors
The greatest amount of sound will leave the garage around and through wood, aluminium or vinyl doors. There is no way to completely insulate this area and retain the use of the door, but you can fill all open areas around the door with fibreglass insulation. Cover the doors with foam sheets cut to fit. Cover the foam with additional fibreglass insulation. Pay close attention to the top and bottom of the overhead garage doors, as these are large areas of space needing to be filled. Consider the cost and complexity of building anechoic panels to attach to the interior of the doors. These can be securely attached to the doors on a frame made to be removed if access through the doors is necessary.