Hi guys. I'm renovating a building that supposedly used to be a photo development studio, and turning it into a humble little music studio. The building itself is about 35'x20' and houses two rooms, a mix room and live room. The mix room is a new addition for us, and was previously being used by the landlord (we're renting) as a storage space. Our current goal with this renovation is to isolate our mix area from the live space (not necessarily from the outside) and also treat the interior of the mix space.
Don't ask me why, but when the building was built, someone decided to put a big cavity in the foundation, as indicated in the attached photos and drawings. The cavity is 7' wide, 14' long and approximately 3' deep. Unfortunately, the cavity spans underneath the wall dividing the mix and live room. :( . Currently, the pit is filled with chunks of asphalt (vapor barrier?) and is then stuffed with carpet padding.
My initial thoughts were to shove all of that carpet padding underneath the live room cavity, then build a sandbag wall underneath the floor to separate the space. This would probably help, but wouldn't defeat the fact that the plywood and framing on the pit (as shown in the photo) would be one continuous, resonant piece spanning between rooms.
How would you guys go about resolving this? Keep in mind, this is a rented space being built by a recent college grad, so budget is a huge issue.
Resonant Cavity between mix and live space.
Originally posted at johnlsayers.com, topic 19666.
That's a tough one. That's a major flanking path between the rooms.
What I would probably do in that situation is to fill it with dry sand to just a few inches short of the top, then use several layers of 3/4" on top of that to build up to the same level as the rest of the floor, carefully caulking each layer, of course, to seal it to the sides. The sand could be in sand bags, as you suggest, or just poured in loose. Either way would work.
That way if you ever do leave and the landlord wants his "tomb" back again, then you can pull out the plywood and dig out the sand.
As long as it is damped by full contact with the sand underneath, there's no problem. Of course, you'll need a layer of plastic in there, in case the sand is damp or wicks water from below. One thing, though; I would not leave any empty space down there: Fill it all with sand bags or sand. You do NOT want resonant cavities under your rooms! - Stuart -but wouldn't defeat the fact that the plywood and framing on the pit (as shown in the photo) would be one continuous, resonant piece spanning between rooms.