Framing Isolation

Hello! I am working on finishing up a design for a studio and I need some advice about isolation mounts. My ceiling (double-layer of drywall) will be supported by hat channel and RSIC-1 clips. It will be decoupled from the walls of the rest of the structure by a 1/2" gap, which will be filled with acoustic sealant. I have spaced walls with double layers of drywall. These walls are decoupled from the structure as well as each other (each room is isolated), but we will need to support the walls structurally. My contractor would like to connect the top plates of the wall framing to the roof framing (above the rooms will be rafters and collar ties). He had originally planned to do this with WIC clips, but I read somewhere that those really aren't for vertical support like that. So my questions are... 1. What would you suggest is the best ceiling isolation hanger? Price is a big consideration here. 2. How would I space/arrange the hangers? (this might require me supplying the floor plan and ceiling dimensions, which I don't have with me at the moment.) 3. Where can I get said product at a good rate? Preferably E-commerce site, but if I can get a great deal by calling someone I'm open to that. Anything you can do would be a great help. Thanks! -Brad http://www.blindmanrecording.com

but we will need to support the walls structurally.

Is there any reason why you cannot build a proper complete MSM structure (walls and ceiling as one unit)? Or a reason why you cannot sheath the inner-leaf framing with plywood, to give it structural integrity, if for some reason you really have to hang the ceiling separately? You could use sway braces, but to my way of thinking it makes more sense to make the inner-leaf as a single one-piece self-supporting structure. (Unless of course code requires sway braces...) More details on your situation would help to clarify. And please also read and follow the the forum rules. - Stuart -

The separate ceilings were a suggestion by my designer, and I didn't really question him on that. But your plywood idea seems pretty good. I will check with my contractor to see what he thinks about that. Thanks! -Brad

The separate ceilings were a suggestion by my designer, and I didn't really question him on that.

You'd get better isolation by resting the ceiling joists directly on the inner-leaf walls, and thus totally decoupling it from whatever is above it. Plus, that would help to give the walls some extra integrity, too, as the ceiling structure would tie the tops together. It also makes it easier to get a good long-lasting seal between the ceiling and walls. But again, if you post more details on your design plans, folks here can take a look at it and suggest ways of improving it. There may well be other issues that need attention. - Stuart -

Thanks, Stuart. At this point, I only have a handful of things that I'm wondering about. I have hired an acoustic designer to put it together for me, but he's not quite as concerned about the price of the whole thing as I am! My contractor wants to use the WIC clips, which would run me $1200 by the time he was done, just for the clips. So I'm exploring cheaper options that will still get me structural integrity. If you look closely (and make an assumption or two) at my description, you will notice that the ceiling is on hat channel and RSIC clips. This is because it is attached directly to the roof rafters and collar ties. This not only maximizes the space in the rooms (I would lose an additional 4"-8" in height for ceiling joists under the rafters), but it eliminates all ceiling framing, which brings the cost down (of course, with all of the clips and hat channel, it might work out to be the same). Here are the drawings of the layout and the side view. This is a two-car garage with 8" cinder block walls, 24-on-center 2 x 10's for rafters, and we're raising the collar ties (the cross pieces in the side view) to get some more head room in the building. All of the walls are 2 x 4 studs with a 2" space from the outside and from each other. There are two layers of 5/8" drywall on the walls and ceilings. The bays and the space between the walls will be filled with R19 insulation.

(I would lose an additional 4"-8" in height for ceiling joists under the rafters),

No you wouldn't, if you built the ceiling either "inside out", or using Rod's "interleaving" technique... :) In both cases you would not need to lose any more than the thickness of the drywall, plus maybe a slight extra margin for safety. And in both cases you'd get the benefit of the extra isolation, plus the reduced costs for NOT having to use those expensive clips, channels and sway braces. I'm betting that a bunch of lumber works out an awful lot cheaper than all of that hardware...

but it eliminates all ceiling framing,

Actually, ceiling framing is a GOOD thing! It gives you some place to attach all the things that you will need to hang up there later, such as clouds, lights, HVAC registers, other acoustic treatment, etc.

Here are the drawings of the layout and the side view

Could you mark the rooms on the plan view, please? So that we can see which is which. Two are marked on the elevation, but the orientation doesn't match the plan, so its hard to figure out... Also, the plan view doesn't show your doors and windows: it would be good to see where they are, too!

All of the walls are 2 x 4 studs with a 2" space from the outside and from each other. There are two layers of 5/8" drywall on the walls and ceilings. The bays and the space between the walls will be filled with R19 insulation.

That part sounds fine! Are you going to use Green Glue? Also, how do you plan to do the floors? - Stuart -

I doubt that this will be much help, but this is what I ended up using in a similar situation. What happened to me was the ceiling framing was inadequate for the ceiling load, at least as far as I was concerned. So I used these http://www.mason-industries.com/masonin ... h610v8.pdf from Mason industries. Mine are type 30n. These can come with a variety of hanging options from simple threaded studs to eye-bolts (which I opted for). So far only half of the ceiling is up, but so far so good. The guy at Mason did all of the calculation based on my information and floor plan and supplied a diagram to work from. Not all of the hangers are the same rating as some hold more load depending on their location, like how close they are to the edge of the ceiling. I am thinking this is a better solution than using a "one size fits all" clip, but I'll stand corrected by someone in-the-know. They aren't cheap though. Price depends on the weight rating of the hanger. For me, it was a wash between several options and these seemed to best fit what I wanted to do. I know that you have a consultant, but keep in mind that ceilings are heavy and you have to make sure that your roof can hold the load. If you have snow, consider that weight too. Hope this helps. EDIT: After rereading your initial post, I realize that you have no ceiling framing, so my suggestion won't work for you. Not only would you need framing, but you would need at least a foot between the ceiling and roof joists for your hangers. Sorry. :oops:

"In both cases you would not need to lose any more than the thickness of the drywall, plus maybe a slight extra margin for safety." With the walls framed like they are, with the angle, it would be impossible to do this. The joists will have to go from front to rear, rather than following the existing rafter placement. So the height that will be lost will be dictated by how far that span actually is which will determine what thickness of joist will be used. The actual lose of headroom could be anywhere from 7 inches to 12 inches, possibly more.

Clips can cost as low as $0.40 a square foot, capable of holding 25 gauge channel and 2 sheets of 5/8" drywall. $0.50 if using three sheets of 5/8", so keep that in mind when they're throwing huge numbers at you.

I updated the drawings above with labels, and I corrected the side view drawing (and included the opposite side view). The sides are not precisely to scale, just rough to give an idea of the space.

Soundman2020 wrote:

(I would lose an additional 4"-8" in height for ceiling joists under the rafters),

No you wouldn't, if you built the ceiling either "inside out", or using Rod's "interleaving" technique... :) In both cases you would not need to lose any more than the thickness of the drywall, plus maybe a slight extra margin for safety. And in both cases you'd get the benefit of the extra isolation, plus the reduced costs for NOT having to use those expensive clips, channels and sway braces. I'm betting that a bunch of lumber works out an awful lot cheaper than all of that hardware...

Can you please expand on that? The reason there are any connections at all between the ceiling and the roof is that my contractor was concerned with structural integrity of the rooms. If you have a solution that involves none of those clips or hat channel, I'd be willing to consider it.

Soundman2020 wrote:

but it eliminates all ceiling framing,

Actually, ceiling framing is a GOOD thing! It gives you some place to attach all the things that you will need to hang up there later, such as clouds, lights, HVAC registers, other acoustic treatment, etc.

At this point, my lights will be sconces on the walls (so that the holes in the sound barrier will only need to be the size of the wire, then caulked), and I won't have HVAC vents there. I will have a cloud (I'm assuming those are the sound treatment baffles that you hang from the ceiling?), so I should find out how much weight my hat channel will hold. I have no direct plans for floors. Probably some product to moisture-proof the existing concrete, then a pad and carpet. Any bright ideas?

wildbagel wrote:

Any bright ideas?

Three...please fill in your geographical location as we are working blind here as to what you can or cannot do, etc. >"I have hired an acoustic designer to put it together for me..." >"is that my contractor was concerned with structural integrity of the rooms." Get these guys to talk to each other. If they are any good at all, your standing in the way of progress ;) You should be writing checks not learning how to do their jobs for them.