Framing Techniques for Ceilings

My Plans - I've been planning out the section of our basement that will be a single room isolated for rehearsal as the main purpose. I've read Rod's book cover to cover. I've been poking through threads and reading accounts of all different types of sound isolation projects and I've come to a question of how the ceiling of a room should be constructed in reference to the joists of the deck. My primer to all this was Rod's book and when discussing this topic there are a few techniques covered. Explaination and Question - The one I find is most comon in this forum's construction diaries is with RC channels affixed to the joists where the ceiling joists would be screwed to. The book covers this example quite well, but goes on to say that the most effective ceiling for isolation is one that is decoupled or separate from the deck above and is independantly framed; resting on the wall frames for its support. This makes the most sense to me because there is no solid contact between the two sections. I've seen some studio examples that have used this, but I have found that most basement construction highlighted here use the RC method. My thought for this being a preferred method has to do with the amount of air space available for a basement construction. For instance, someone dealing with an 7.5' deck to slab basement would not have more than an inch or two of clearence. Perhaps the space is better dealt with by doubling up with drywall on the interior of the room. So to clarify my question - Is there a relative point of distance/space/realestate for an independantly framed ceiling from the deck above where the isolation compared to an RC hung roof is the same or not as effective? Details Of Our Basement - 7.5' height to the joists. 16 wide. centerbeam breaks the section up into two sections - 10 & 11 (once the walls ar econstructed, that length would be cut by ~1'..) I plan on boxing up the column support to double as framing support for a header to support the independantly framed ceiling if I were to go this way.. The column is positioned in the center of the beam span from wall to wall. And Please - If you know a project this was discussed or covered in any way - let me know! I've photographed a portion of Rod's diagram as a reference for an independantly framed ceiling. (semi independant framed ceilings are also covered, but I've not seen an example in the forum of someone using those rubber hanger assemblies..)[/b]

I think you'd have a really tough time getting an independant ceiling framed in without losing too much ceiling height. Even if you could fit your ceiling joists between the existing floor joists (assuming you could move any HVAC and cross bracings could be handled)...you'd still need a couple of layers of drywall on that ceining to make it massive enough to stop bass from just resonating through it. FWIW I built my ceiling using rubber hangars and furring channel (and 3 layers of drywall plus green glue). My ceilings are not the weakest part of my studio...now flanking paths around side walls and windows are! The hangarsd are easy to work with, and less chance of 'shorting out' like RC can. You do lose about 1" of height though by using them, (I had 8'10" slab to joists to start with and now I'm down to 8'6" floor to ceiling). Cheers, Kris

Thanks, No HVAC to deal with. Actually, the section I had this in mind for is on the side of the main support where the joists are totally clean of any utilities. Why, it's a blank canvas! The other side, I've got some plumbing work to deal with. I'm rerouting copper for the forced hotwater heat, and shortening a trap (moving it up closer to the ceiling) for the toilet's line. The section containing all the plumbing is my only barrier in the ceiling and I had assumed that I would use either RC or another technique. I've stll been searching threads and not found an example of someone doing this.

If you're looking for more information on the rubber hangar assemblies, you'd be best off searching for RSIC or 'clips' as a keyword. As far as the independant ceiling is concerned I'm afraid I don't know anything about it other than it will provide for the best isolation. However, you'll need to be sure that it can support the weight of drywall that you want to hang on it. Are there any supports (I beams) in the way? Cheers, Kris

drfrankencopter wrote:

As far as the independant ceiling is concerned I'm afraid I don't know anything about it other than it will provide for the best isolation. However, you'll need to be sure that it can support the weight of drywall that you want to hang on it. Are there any supports (I beams) in the way?

Hanger Assemblies I feel very confident in the use, application and physical behavior of hanger assemblies. History - I've even worked a couple of jobs for a place dealing with Govt Mil. contracts where isolation was the goal. They threw money at the problem and we put triple layers of drywall up with much insulation, but I worked on 4 meeting rooms with suspended ceilings and we used similar clips. Theory In Use A ceiling that doesn't touch the deck above does not transmit the vibration through direct contact. The sound would have to bridge the air gap. This principle seems pretty solid to me. Pair the advantage of less weight supported by the deck; More layers of drywall could be put between the deck's joists if this would be of a benefit. So back to my original question in regards to this theory - Is there a point of proximity to the deck above (less air) where going with Hanger Asseblies would provide greater isolation. Every physical theory has a curve in performance as it nears the boundary. Or is it just a matter of it being easier to build for the benefit of space? Span The span for the ceiling frame would be less than 9'. If the ceiling was made with 2x6 staggered 16'' on center opposed to the deck joists my assumption would be that 2 layers of DW could be suppored. Center beam - This is actually an advantage for the weight of the ceiling. There's a support pole in the middle that I plan on framing around and resting header beams ontop of the box frame of the pole. Combined with the two wall frames to rest upon, this would create a strong header span in the mid point of the room. The other side is 1 more foot of length, but the hitch is a bit of plumbing for the bathroom and heating. I can re-route the heating easily and that would leave a 4x4 corner having to accomidate the drop. Contact Points From Wall To Outside Fireblock that would reach out to the top of the foundation, The door assembally (double wall assembly for the non foundation wall) The floor/slab. Perhaps a few clips to the walls of the foundation for stability. Given the lack of reply (and btw - very happy you are replying drfrankencoper!) I'm starting to feel that I should get "uber organized", take pretty pictures and make decent drawings to spec this out. Write a scope and review of work to get feedback on this part. I am doing this construction this summer so I may as well put it all together in my head and on disk.

I think to get a better response to your question you need to say explicitly what types of ceiling construction (including the floor above) you are comparing. Include details like the depth of space between the leaves for all possible construction options you're considering. Photos of how you plan on handling the support beam might be useful too.... Without knowing the full details of what you plan on building I'd say that you will get better performance by building a seperate ceiling, and adding additional drywall between the joists, secured to the floor above. Why not use some green glue there while you have a chance! Cheers, Kris