Soundproofing An Exposed Joist Ceiling
The following soundproofing treatment targets the elimination of sound bleeding through a ceiling that will be finished off with drywall, but is currently an exposed joist ceiling. As we outline in our course on Sound Transmission, sound waves travel structurally through common contact points. In a floor/ceiling assembly, the joists that support both the floor up above and the ceiling down below are the focus of our treatment. To impair the assembly's ability to conduct vibration, our goal is to line the surface with density, and force the collapse of the sound wave through structural disconnection.
STEP 1: Add Your Density
Start by stapling a layer of dB-Bloc direct to the face of your ceiling joists. The weight of this barrier membrane will serve to help deaden your ceiling's ability to resonate. By controlling its vibrations, you control sound transmission. The material is extremely heavy, but measures just 1/8" thick. Cover 100% of your ceiling with this mass loaded vinyl.
STEP 2: Add Your Disconnection
Once you have the weight of dB-Bloc assigned to your ceiling, your next step is to create a disconnection in your ceiling configuration. Furring strips are simple 1x3 wooden slats that you can purchase from your local building supply center. Apply a set of these strips to your ceiling, running them perpendicular to the direction of your ceiling joists. Anchor them by drilling 3" long screws through the strips, through the dB-Bloc and into the ceiling joists. Then finish your treatment by applying a layer of 5/8" drywall to the face of your furring strips.
STEP 3: Flanking Path Treatments?
Your goal with your ceiling is to eliminate as many cutouts as possible to prevent the bleed of noise through any openings. Light cannisters, exhaust fans, and other openings need to be treated for the escaping noise. We recommend you install track lighting if possible to reduce your cutouts. If you are intent on installing recessed lights with cannisters, be sure to install NetLag above your light cutouts prior to hanging your dB-Bloc. NetLag will help combat the bleed of noise through your openings.