Fine tune my ceiling plans.

Hi, frequent reader first poster. I have recently gained a larger room for my live room (minus one room mate plus one big basement). I own Rod Gervais' book and I have read up quite a bit online. I think I have a pretty good plan for my ceiling, but I wanted to throw it out there for criticism and ask a couple of questions on the more arcane details. Here is what I've got: Future live room: Here is the ceiling to be worked: But I found a new enemy, I call him Duct the Bastard. Here is his picture, hopefully one of you has a good idea for how to battle him: So my general plan is to follow Rod's ceiling design on page 67-70. I am going to cut drywall and put it in between the joists with backer rod and caulk along the edges. I'm thinking of green gluing two pieces between the joists. I will then insulate over that. Depending on how much transmission is going upstairs (I use a scientific method involving my drum set and my girlfriend doing homework upstairs) I may decide to put in a resilient channel on the ceiling with drywall. I'm putting off the last step just because my ceiling is fairly low. Here's what I don't get: What would be the order of operations for installing the drywall, backer rod, caulk, and ledger board along the joists under the added drywall. In the book, he recommends using finishing nails to temporarily hold your drywall up. This would indicate they would eventually be removed. It appears the real weight bearing part of the job is the 1x3 ledger board underneath. At what point do you remove the nails while caulking, adding the second layer, putting in the ledger board? Also I have some nasty pipe and air duct issues. How compromised will my plan be if I just wrap the pipe intensive sections with insulation, since I can't get drywall up around the pipes?

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Okay, not a lot of help yet, but maybe I need to be more proactive. Here's what I'm thinking my options are for that duct (which has a bottom side flush with my ceiling joists): 1. Since the duct is already framed by joists that run the length of the room I could put some thick insulation along the sides of those joists and then put something thinner underneath like 1"703 and then perhaps I could fit that under the resilient channel that will run the length of the ceiling. Or, 2. I could build a plywood soffit filled with insulation that hangs an extra three inches down where the duct is (in the middle of the room) and then add a separate lower resilient channel just where the soffit is to decouple the drywall from the plywood. 3. I could make a decoupled soffit filled with insulation.

losthighway wrote:

Okay, not a lot of help yet, but maybe I need to be more proactive.

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losthighway wrote:

2. I could build a plywood soffit filled with insulation that hangs an extra three inches down where the duct is (in the middle of the room) and then add a separate lower resilient channel just where the soffit is to decouple the drywall from the plywood.

This is close to what I am thinking. Only different. At the specific joist/duct area you could fur the joist down a specific dimension. Any space you can develop to keep from binding against the duct metal. You "could" insulate but you really do not have the room. So I would install mass here, multiple layers of rock. If the span is so great that you have concerns of eventual sagging of the rock, use construction glue and adhere the panels together. Or use plywood as the base and apply the rock to that. Watch your depths and screw lengths!!! You do not want to pierce this metal and it can happen faster then you can say, aw hell!

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xSpace wrote:

At the specific joist/duct area you could fur the joist down a specific dimension. Any space you can develop to keep from binding against the duct metal. You "could" insulate but you really do not have the room. So I would install mass here, multiple layers of rock. If the span is so great that you have concerns of eventual sagging of the rock, use construction glue and adhere the panels together. Or use plywood as the base and apply the rock to that.

Very cool idea. The duct is only about three feet wide, so I think if I screwed the sides of the drywall in every six inches, the middle shouldn't sag much. I'm wondering with that design, if greenglue would be beneficial, or a worthless expense. Meanwhile, I am pretty sure I am going to do an RC2 type channel for the rest of the ceiling, even though it's only 7.5' high I figure I'll only lose an inch and a half or so. Fortunately I can do this in phases, and check my progress. So, if I do your idea with extending those joists and also finish my double drywall plus insulation between the other joists, I can have someone play some drums and see if it's getting close enough. Big question for me (limited construction experience), what sort of wood/fastener combination would I use to do your idea (boards along the outside of the joists that hang down, or straight under, screws, brackets etc.) Also, is it a good idea to buy some kind of hot water pipe tubing, to wrap my pipes before they sit next to R-13?

You could use the 3/4" batten boards you are going to remove from your overhead ceiling as furring. You are or are not going to remove them[3/4" boards]? I would try to develop some kind of a plan as to your wall placement and dividing up of the space. It would be great if you could work that duct into an area that did not make such an intrusive "bump" into your room. Just for the way it looks and more importantly, it takes extra effort to go around something rather then directly over it.

Well, unfortunately there's no way around it being straight down the middle. That big room is all going to be the live room, I already have a slightly smaller room for a control room, and another small room for iso/storage. Sleeping on the idea of furring- those little boards could be used to mount extra drywall on. But if I'm putting drywall between the extended joists they would only leave space for about one 5/8" piece. So as for the furring, if it is right outside the normal joists I could screw the drywall in to the actual joists like the duct metal was actually screwed into the joists. This makes me question the purpose of the furring, except perhaps it would offer more isolation from sound hitting the side of the duct channel, and added drywall assembly. *more mass* I could use the existing little boards so there would be somewhere to screw the drywall in, in the middle. This would also create a little 1/2" space between the added drywall and the duct. I could fill this gap along the sides with backer rod and caulk. That design would seem to benefit from green glue IMO. The only remaining question in that situation is whether or not to create a lower resilient channel there or not. I suppose if I was really crafty the other parts of the ceiling with the RC could be flush with the added drywall of my duct channel. It would only be a question of doing the math so the 1/8's of inches matched up.

"It would only be a question of doing the math so the 1/8's of inches matched up." And that is exactly where I was at. Furring the thing down was/is only to keep the sheetrock from being pinched up against the duct metal and allow some type of damping to be placed in between the two. So gluing the rock to the metal was part of the plan...construction glue, not green glue. You are trying to stop a thin piece of metal from moving around if it is not damped some how.

Okay. I think I have a lot to learn. The idea of furring, may not have been fully grasped on my part. So maybe the small boards that run across the duct are beneficial as they are (?). I think they are attached with adhesive. If so I could begin putting the layer of drywall underneath that, without building an additional structure (soffit). Perhaps reinforce the sides of the duct where the joists are to prevent sound from entering the side of the air duct. Forgive my novice-ness.

No apologies needed. Your doing fine on your own ;) However you do it, because either one will work, the goal is not to bind one piece of material against the other. So you can fur it down, but you should fill the void created by this method with a suitable insulation type of material. This would be the better of the two but will most likely interfere with the line being straight on your ceiling. OR, you can simply install the sheetrock directly to the joists and over the metal. But you should place something between these two pieces of material[duct metal and sheetrock] as well, and for the same reason. You can glue the metal and rock with construction glue OR you could even place a piece of exterior builders house wrap in between the two. What you are trying to do is cover/add density and dampen an area that has potential to move everytime air moves thru this duct. You'll get it.

Ok. I think I get it. Here's what I think will work: Leave the little boards crossing the duct and going down the joists parallel to it. Put 1" 703 against the metal (only cause it's dense and small), screw drywall in under that (over it really but since we're working downwards). Once I've dampened the duct and added my first drywall layer I will either: a. Add a few more layers of drywall right under the first. b. Add a few more layers of drywall with green glue in between.