Ceiling question - whats the best solution?

Im working on finalizing the design for my house addition. Its going to be 22'x25', connected to 2 existing walls on my house. Im planning on room within a room construction, and for the walls its pretty straightforward. However, for the ceiling, im still a bit unsure what the best way to do it is. Here are the possibilities as I see them: 1. Hang the outer leaf from the truss joists, and then hang the inner leaf off of joists sitting on the inner walls. This seems like the most decoupled scenario, but I wonder if the joists will be able to handle the load. The span would be 22', with one inner wall that could help support the joists, but is that enough? 2. Build the ceiling 'inside out', as I have read here. I think this means putting drywall both above and below the joists and filing the cavity with insulation. Is that right? It seems like it would be a pain to cut the drywall for the side above the joists. And I think I would still have to decouple the inner leaf with rsic clips or something similar. 3. Hang the outer leaf from the bottom of the truss joists, and then use some kind of decoupling hanger for the inner leaf. This would eat into the headroom, but is feasable. Which is the best way to do the ceiling? Thank you for your help. --Byra

1st option is your best bet. but you may have to use some decoupled hangers to support the inside ceiling span. don't have enough info to be more specific nor am I a structural engineer. You will need to consult an engineer about the loads you're going to have to hang off your trusses anyway. Is this going to be a single room studio? You will only get out of this place what you put in. The more info we have to work with, the better answer you'll get. And you may wish to read the stickies about what to do before you post. Steve

Byra time to think outside the box here...... why do you need an outer "ceiling" ? If you use a sissors truss - not only would you cover all your tracks for the outside building frame - but you would create a high spot in the center of the room where you could then install an LVL beam - your inside ceiling could have pitch to it so as to maximize ceiling height and increase room volume. Your inner wall height would only have to be 1" below the outer wall height - just offset your inner joist from the trusses themselves - there is no action on the walls other than the gravity load because an LVL beam will carry the ceiling load easily. Thus no need for collar ties to hold the walls in place. A win win situation........ Rod

Hi Rod, Thank you for your reply. Im trying to understand exactly what you are suggesting. For the LVL beam, do you mean that it would sit on the outside walls? Would it be shaped like the scissor truss, with a peak in the center? And would it somehow support the inner joist/ceiling? Im having trouble envisioning the inner ceiling framing. As for the isolation, the inner ceiling would be one leaf. Is the roof the outer leaf? Ive attached a drawing of the addition (without the trusses) next to my existing house. Its a one room studio, with an iso room and a bathroom. Thank you for your advice! --Byra

Rod, Do you mean something along these lines (in the attached drawing)? If so, would I then attach drywall to the bottom of the inside truss, insulate above it, and then the roof would be the outside leaf? Thanks!!!

Byra wrote:

Rod, Do you mean something along these lines (in the attached drawing)? If so, would I then attach drywall to the bottom of the inside truss, insulate above it, and then the roof would be the outside leaf? Thanks!!!

Byra, yup - those are the lines - you didn't draw a sissor truss - BUT - you could do just a beam carrying on the outer walls for the roof above - (with standard rafters) and then the same for the one belowbearing on the inner walls for the room within the room...... Even more free space....... although you want to make sure to leave enough space between the 2 for HVAC duct runs. Rod

Byra - this is what Rod means by a scissor truss.

Thanks John......... I don't have loys of time to answer right about now - never mind draw up a sketch. Rod

Thank you Rod and John for your help and advice. I have changed the design of the room accordingly, and now have a vaulted ceiling running the length of the room. Since this room will be used for mixing as well as tracking, I need symmetry about the mix position, and have it as shown in the drawing. The desk is sitting in the mix position. However, the vault concerns me. I have searched here and read all of the relevant threads. It seems that the main problem is that there will be focused reflections from the vault back to the mix position. However, these can be controlled by ceiling clouds. Is this correct? IE, is this still the best way to go (vault+treatment)? BTW the vault peak is about 12 feet and runs down to the walls at 8 feet. The room is 17x25 feet. Thanks for all of your help!