Rehearsal studio, new construction ceiling

Greetings everybody, and thank you for the wealth of information on this site. I have read many of the posts here, as well as Rod's 2nd edition of "BILTP". (which was a fantastic read, except for the math - my goodness). I have a commercial unit inside a warehouse. The usable space of the unit is 27' wide, 60' deep, and 14' tall. The unit is seperated from neighbors on each side by concrete block walls, using standard 8x8x16" hollow masonry blocks. The ceiling of the warehouse has exposed steel Z beams running the width, an insulation on top of those, and then I can only assume the roofing structure. The flooring of the unit is a concrete slab of undetermined thickness. No neighbors above or below, as this is a single level construction. My plan is to build a rehearsal studio inside the warehouse. This means the only recording that would take place is simply the live sound of a practice. The studio is more for the rehearsal side of the business. Sound isolation is very important to me to stay in good graces with the neighbors, while letting bands practice at or near full show volume. I wand to build a completely enclosed studio to make this happen. My initial plans would be; Double stud walls on three of the four sides. (The fourth side would be placed within inches of one of the concrete clock walls) Double drywall with Green Glue on the inside and outside, and insulation. If I understand correctly, this is a good double leaf system with an STC of 63. (In the case of the "fourth wall", it would be double drywall with Green Glue:stud wall:insulation:air gap:concrete block wall) The ceiling will be newly framed, with the joists attached to my inner stud wall. This brings me to my question; If a system is only as good as it's weakest link, that would be my ceiling. As I understand, my best option is to hang double drywall on the ceiling using a RISC assembly. This accomplishes mass and decoupling. Insulate the ceiling for absorption, and the GG does the dampning. But this doesn't provide the same amount of isolation as my double stud walls, does it? So, are the double stud walls just wasted money? Is there a ceiling option that I have overlooked? Thank you to eveyone for your input and ideas! -Bryan

Hi Bryan, and welcome to the mad house! :) One question here: are you planning to use the entire space for the rehearsal room? Or are you planning to include other things in there too? Alternatively, are you planning to leave a large gap between the existing concrete block walls and the studio? The reason I ask is because it seems like you are planning a three-leaf construction. If you build a double-stud wall with drywall on each set of studs, then you are adding those two new leaves to the existing leaf, which is the concrete block walls, making a total of three leaves. I'm not sure I understand why you want to do that. The only thing I can think of is that you plan to leave very large air gaps around the studio, between the existing outer leaf and the two new leaves, but that seems like a waste of space to me.

The ceiling will be newly framed, with the joists attached to my inner stud wall. This brings me to my question; ... As I understand, my best option is to hang double drywall on the ceiling using a RISC assembly.

If you are going to rest your inner-leaf ceiling on your inner-leaf walls, and they are fully decoupled, then you do not need RSIC clips. The clips are designed to decouple surfaces that would otherwise be coupled (eg, on two sides of a single stud wall), but in your case you say you are going to build separate double stud walls, fully decoupled, so you don't need the clips. Partially decoupling something that is already fully decoupled serves no useful purpose.

If a system is only as good as it's weakest link, that would be my ceiling.

Most likely not. It is much more likely that your weakest link will be your doors, windows (if you have any), HVAC ducting, or electrical installation. It is relatively easy to get 65 dB of isolation from a wall or ceiling, not so easy to get that from a window, even harder to get it from a door or HVAC system, and really hard to get it from a badly installed electrical system. All it takes is one ignorant electrician to cut a hole in your wall to install a light switch or outlet, and your entire isolation just went down the drain. IT sounds like your wall and ceiling plan is heading in the right direction, but you didn't mention anything about your plans for doors, whether or not you will have windows, what type of HVAC system you are thinking of, or how you plan to do your electrical work. I'd be focusing on those things, after you get your wall issue sorted out. - Stuart -

Stuart, thank you for your quick reply! I appreciate the effort. Let me answer a few question to see if I can clarify; As far as using the entire space for the studio, the answer is an un-clear "almost". As I said, the width of the location is 27'. I need to leave a hallway down one side of the unit, (either 3 or 4 feet, tbd by code), so the width of the studio will be ~24' (minus material thickness). So, that means there will be a large air gap between the double stud walls and the concrete wall on the hallway side. The same goes for the other two double stud walls. There will be an air gap of over four feet beyond these walls. The exception is the one wall that I need to place as close as possible to a concrete block wall. This is the wall that I was only going to make a single stud, to avoid the dreaded three leaf design. I believe I understand about the ceiling now. As it's framing joists will rest on the inner leaf wall framing members, it is considered decoupled. So the ceiling leaf design will be as follows; double GG drywall:joists:insulation:air gap of about one foot:existing ceiling/roofing. As far as the other issues brought up, I wanted to ask some questions about HVAC also, but I wanted to keep my first post neat and clean. I do have the luxury of running the HVAC ducting as needed. My assumption is that it needs to get inside an insulated soffit ASAP, using flex duct, to prevent it from transmitting sound. This would be preferred over running flex duct outside the ceiling, dropping in supplies as needed, I assume? Doors; I will construct two "super doors" as per Rod's book. No windows. Thanks again for all input!

I finally made a quick sketchup to give everyone an idea of the initial plan. When you look at this screenshot, understand that the outer transparent cube represents the existing walls and ceiling of the existing unit. I have omitted that on one end, the existing unit extends further, and has the entrance, offices, etc.... Thanks again to all!