I am going to be creating my first soundproof door assembly. I have my idea down for the frame and door itself, but the problem is going to be that empty space between the door assembly and framing of the wall.
A few ideas I've had:
- Get some MLV (mass-loaded vinyl) and backer rods. Wrap the backer rods with MLV and stuff them into the cavity. The rod will allow for compression which would give a tight fit.
- Sand. This may sound insane, but I figure I could create a custom casing that I could slide into the cavity, after which I would pour sand into it from the top. The casing would eventually fill up and expand to fill the cavity. The only thing I might have to worry about is settling which would require it to be refilled a bit at the top, but perhaps there's a type of heavy sand that wouldn't settle.
- Green Glue. Using my MLV/backer rod method, an idea came to me to create an actual sheet of Green Glue which would serve the purpose of the MLV. Basically, I would get some heavy-duty plastic, spread GG liberally out all over it, then put another layer of plastic over the top. If I gage the thickness with something that's about 1/8" like some thin dowel rods running along the length of the inside and then setting something heavy on top to flatten it out and disperse the glue, I think I can get a consistently level sheet of GG compound. GG thickens up after a few days, so I wouldn't have to worry too much about any of it squishing out all over the place.
- Safe 'n Sound insulation stuffed liberally into cavity.
Since my door is going to consist of a layer of plywood, GG, cement board, GG, and plywood all in that order, I am sure it's going to have a fairly high STC. Therefore, I'd like to make sure I get the edges around the door really well even if it means the edge has an aburdly high STC in comparison to the wall and door assembly themselves.
Best Answer
Noiseproofing, as you know, is best assisted by decoupling dense masses.
I am going to presume that your walls are framed thicker than standard 2x4 (as staggered 6 is a very common technique)
In this case, you have a pretty wide cap to fill in the shimmed jamb.
I would shove fiberglass into the cavity, or spray in foam, making sure not to overfill!
Then I would lay in greenglue (or their gap-filling material), then I would lay in the backer rod. Finally, one more application of the gap-filling material before setting the casing.
Here is a video of a door company demonstrating the install: http://www.acousticalsurfaces.com/acoustic_doors/soundproof_doors.htm