Inside-Out MAM, Short Ciruiting RISC-1, Sand Filled Decks

Howdy! My Design stuff is here Mr. Stanton has directed me hither for these following questions. A couple of things I've been wondering were neatly answered in the Stickies by Nightfly & Mr. Sayers, and the rest well, here you go.. The .jpg I've posted has double plates Top and Bottom.. Can I build like this to increase my mass AND use up the smallish pieces of 2x4 I've been collecting? -edited - redundant ? answered in Stickies Last Question for today, How bad would Inside out M-A-M fare? two inside out walls, back to back? Check the pic and the .skp, I imagine pretty bad, since the air spring is very tiny, comparitvly speaking. Thanks, Ed

i'm no pro, but i would think as long as they are properly decoupled, they would still work pretty well, just not as great as the obvious 'big' air gap between the walls. i'm also wondering if you'd benefit from some insulation in there, or if it would compress it too much, thus coupling the two walls.

As I get more into my build space, I've realized Something, the Garage Floor is Graded! it slopes 7 inches over a distance of 18". This leaves a 4' x 20' section in the back of the garage that i was unintentionally designing around, but hadn't quite realized it. So rather than give up over 20% of the space in my room, I have come to the decision to make some decks to level the floor out. This has some benefits such as being able to run wiring through conduit in the space beneath the floor, not to mention having the control room and one of the smaller rooms being level. Budget constraints dictate building one room @ a time, So the Control room will be finished first, then the others come later. I see building each room on it's own deck, separated from each other by at least an inch. Though I'm still designing I am becoming fond of the Corner Control room concept. I have decided to Specify the Ceiling as RISC-1 / Hat Channel holding 2x 5/8" Drywall/ Green Glue from the wood 2"x6" ceiling joists. The walls are specified as 25GA Steel Framing, 2x 5/8" Drywall with green Glue and Roxul here is how I'm thinking of building the decks - check the .skp How much wieght does it take to "Short-out" a RISC-1 Ceiling when done to manufacturer spec? I'm talking about Roxul and some lights.. I should be way in the tolerance, right? Ed

i would use leveling cement to level the floor. building a deck to make of the space is likely to be more of problem than not...

RISC-1 and Hat Channel are not interchangeable products. Big difference in acoustical isolation properties. Right? Glenn, If I am reading the drawing right, I think he is also talking about leveling his existing floor up to a concrete slab that looks to be several inches tall (6"?). Leveling cement for the rest of the floor, but that would have to be poured concrete for something that thick (to meet the raised slab) wouldn't it? Would filling the cavites in the deck with sand be a decent option since he is on a slab already the weight shouldn't be a problem? There is a thread here: http://www.johnlsayers.com/phpBB2/viewtopic.php?t=8147 ...and I know there is a brief paragraph in Rod's book pg. 53 ~ Bill

sorry, missed that. if you're trying to raise the deck to match, then you're either going with concrete slab or the deck as described. definitely adding as much mass to the deck as possible will help reduce its natural resonance frequency and then ensuring its dampened (not damp!) should eliminate any booming... the RISC and hat channel should be fine. as long as the clips are spec'd to support the weight of the framing, drywall, and insulation. which i believe the RISC-1 are ok for your purpose.