Has anyone ever decoupled soffits? - AVS Forum
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post #1 of 41 Old 05-10-2008, 04:44 PM - Thread Starter
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Hi,
I've been lurking on these boards for 1.5 years now. I appreciate everyone's input and and documentation of their theaters. It's time for me to get involved now (both asking questions and helping others out with any insight I can provide from my experiences).
Now for my question (after some backgorund). Due to existing hvac ducts and plumbing, I will not be able to easily create a sealed box and add soffits within. Would it be better/easier/cheaper to frame the soffits to the existing framework and then decouple the drywall with RSIC-V, or somehow try and decouple the soffit framework with RSIC hangers, and attach the drywall directly to the soffit framework?
Thanks,

Matt
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post #2 of 41 Old 05-11-2008, 05:06 PM
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Hi Matt,

I decoupled my soffits for sorta the same reason. I wanted to maximize the width of my HT and a beam was causing me some grief. I used RSIC clips and hat channel and fastened the soffit upper framing member to the channel and the bottom part to the decoupled wall. It meant a few extra RSIC clips and channel but it worked like a charm. See the pic for how I did it.

Andy
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post #3 of 41 Old 05-12-2008, 06:07 AM
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I did something very simialr to what Andy did using the RISC clips. I built the soffit "ladder," installed the clips to the joists, then used a couple of spring and/or quick clamps to clamp the ladder to the clips, then one by one drilled holes throught the top of the ladder and installed the lag bolts through the RISC clips and top of the ladder to hold it in place. The other side of the cross pieces (the bottom of the soffit going back to the studwall) was just attached to the the already decoupeld stud wall. It seemd a little flimsy while building, but once all the pieces were in, it tightened everything up.

Good luck,
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post #4 of 41 Old 05-12-2008, 07:51 AM
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I decoupled mine using DC-04 clips on them just like on the walls. It was a PITA to install, but in the end it worked prety well. Andy's method looks like it woudl be easier to end up with level soffits than with the DC04 clips.
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post #5 of 41 Old 05-12-2008, 08:00 AM
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I researched this issue quite a bit. I have a large soffit 30" inches roughly and am using rsic-1 on hat channel to hold up the soffit to the decoupled ceiling. I did not want to use DC04 because they are not really designed for forces pulling down, more side to side by the the looks of them. I was worried they would begin to sag, unless I used a ton of them or staggered every other side. I have got one soffit up with no problems so far.
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post #6 of 41 Old 05-12-2008, 08:49 AM
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I did it using DC-04 clips.



Had I to do it over again (which I need to do as my soffit is a bit too low), I would have used Andy's method.

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post #7 of 41 Old 05-12-2008, 10:01 AM
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Cathan -

You saved me the trouble of taking and posting pics (and we all know how long THAT could take!)! Mine would look exactly like yours.

Tom

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post #8 of 41 Old 05-12-2008, 03:04 PM
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Not to hijack this, but I have a similar related question to this. My understanding is that the "ideal" when using RSIC-1 clips is to build the sealed box/room first, then add soffits on top of the drywall. The assumption then being that the soffit is attached to underlying joist or stud.

With this method are there any concerns about acoustic coupling of the soffit to the framing or it it too minimal to worry about?
I know when using RSIC one is supposed to make sure the drywall is not screwed directly to the studs/joists, so hence the question.

Thanks
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post #9 of 41 Old 05-12-2008, 03:40 PM
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Jason - In my case I had to build the soffit on one side of the room prior to drywall because of all of the HVAC stuff that needed to go inside. For the rest of the room I'll be attaching the top plate of the soffet to the drywall using toggle bolts and construction glue. That would keep the post box soffet decoupled.

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post #10 of 41 Old 05-12-2008, 03:42 PM
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Quote:
Originally Posted by tlogan6797 View Post

Cathan -

You saved me the trouble of taking and posting pics (and we all know how long THAT could take!)! Mine would look exactly like yours.

Tom

Glad to keep you from having to enter your construction zone. Wouldn't want you to have to get anything done.

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post #11 of 41 Old 05-12-2008, 03:53 PM
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Hi Jason,

I would be concerned about any arrangement of framing which was only partly decoupled. One has a choice -- decouple the drywall at all points of attachment, or decouple the framing at all points of attachment.

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post #12 of 41 Old 05-12-2008, 08:05 PM
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Makes sense now. Thanks for the responses all.

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post #13 of 41 Old 05-20-2008, 03:18 PM
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This soffit thread gives us all a great opportunity to improve and define a process that all theater builders go through, really. Thanks for starting it Matt

I noticed that an issue that hasn't been mentioned yet in this thread is the use of plywood instead of 2x4s for the framing.

The 2x4s take up some valuable headroom under the soffit, and since every inch is sacred, the use of plywood really is a good consideration.

I have attached a picture illustrating using plywood and drywall to make a soffit. It's fairly self explanatory. (Note: This only addresses a decoupled soffit used to frame out a beam or duct, and does not discuss a false soffit that you might build to balance out the room.)

I would really like to get your thoughts on this assembly. Always learning.

John


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post #14 of 41 Old 05-20-2008, 04:15 PM
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Soffits can be made from plywood or MDF (better). The soffit does not need to be decoupled...decouple the drywall from the soffit.

John's method works well and saves a bit of space; but, it is only effective if the wall (as shown) is decoupled at the joists (above) and floor/slab below.

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post #15 of 41 Old 05-20-2008, 06:21 PM
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I did mine just like the picture above (except I only drywalled it and didn't use MDF or plywood) and like some of the others did. The only thing a bit different was I put both layers of drywall on the wall, and then attached the soffit to that. I'm happy with the results.
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post #16 of 41 Old 05-20-2008, 08:30 PM - Thread Starter
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Thanks to all for the responses. You've given me a lot of good ideas. Sorry I haven't replied sooner. Been put of town for 5 of the past 6 weeks and my father in law passed away recently so the theater has taken a back seat.

Most of you have shown various methods of decoupling the soffit, which was one way I was considering. Dennis suggests just framing the soffit and then decoupling the drywall from the soffit (the other way I was considering). Two of the walls I'm adding (front and back) will be decoupled with RSIC-DC04. The other two are existing (the side walls) and the drywall will be decoupled with RSIC-V.
1. Do I need to put RSIC-V on the front and back walls that will already be decoupled or is that overkill?
2. I kind of prefer the method Dennis suggested except for the extra width it will add to my soffit on one of my walls in order to clear existing gas lines and ducts (I know it's only a couple of inches but I'm already pushing it at 26" wide and I'd have to make the others just as wide to be unoform). I'll probably do a combination of both methods. My question is: If my side walls are mounted on RSIC-V, would it be structurally sound to attach the horizontal portions of the soffit to the drywall, without attaching it the the frame? I wish I could attach a picture, but if you look at picture #5 of John's post above, and just imagined that the wall framing wasn't decoupled, but the drywall was, could I just mount the 2x2 directly to the drywall?

Sorry if none of this makes sense. It's late at night. I appreciate all your help.

Matt
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post #17 of 41 Old 05-21-2008, 06:17 AM
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Quote:
Originally Posted by John Hile View Post

This soffit thread gives us all a great opportunity to improve and define a process that all theater builders go through, really. Thanks for starting it Matt

I noticed that an issue that hasn't been mentioned yet in this thread is the use of plywood instead of 2x4s for the framing.

The 2x4s take up some valuable headroom under the soffit, and since every inch is sacred, the use of plywood really is a good consideration.

I have attached a picture illustrating using plywood and drywall to make a soffit. It's fairly self explanatory. (Note: This only addresses a decoupled soffit used to frame out a beam or duct, and does not discuss a false soffit that you might build to balance out the room.)

I would really like to get your thoughts on this assembly. Always learning.

John

Darn it John! Now you got me thinking about redoing my soffit!!

Actually, having been able do nothing but think about it these last few weeks, I am going to redo the soffit using your picture method. I think I can get a few extra inches of head room.

One question - I assume OSB would work as well as plywood for the framing, right?

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post #18 of 41 Old 05-21-2008, 09:37 AM
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Hi Matt,

1 - You do not need to put RSIC-V clips on the front and back walls. That would be overkill. You already have them decoupled with the DC-04s. You only need to decouple once, and it sounds like you've done a good job of that.

2 - The benefit of the soffit that I illustrated is to reduce its size to attain additional headroom, or in your case making them less wide.

You could just anchor the 2x2 to the drywall with a few drywall anchors (molly,or toggle bolts) and adhesive (Not GG) like Liquid Nails. It would be too much effort to insert another row of clips and hat channel. If you have double drywall you will have a very sturdy wall to add these anchors.

Hi Michael,

Yes. OSB would work for the framing. It's bit heavier and less expensive than plywood, and will work fine. And as Dennis mentioned MDF is better because it is denser. With MDF you need to make sure not to not blow out the MDF laminations when screwing. Always pre-drill MDF and be very careful.

John

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post #19 of 41 Old 05-21-2008, 12:39 PM
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Quote:
Originally Posted by John Hile View Post


Hi Michael,

Yes. OSB would work for the framing. It's bit heavier and less expensive than plywood, and will work fine. And as Dennis mentioned MDF is better because it is denser. With MDF you need to make sure not to not blow out the MDF laminations when screwing. Always pre-drill MDF and be very careful.

The MDF screwing factor is the very reason I'd rather use OSB. One could still use DD/GG and just have three layers at the end.

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post #20 of 41 Old 05-21-2008, 06:16 PM - Thread Starter
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Thanks John. That's what I was thinking too. Now off to calculate the number of RSIC clips I'll need.

Matt
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post #21 of 41 Old 05-21-2008, 07:36 PM
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....ah...but we never screw into the edge of the MDF.

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post #22 of 41 Old 05-22-2008, 10:13 AM
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Should there be such a concern about headroom under a soffit? I mean, how often do you walk around the perimeter of your theater right next to the wall? Just wondering aloud...
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post #23 of 41 Old 05-22-2008, 10:18 AM
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Quote:
Originally Posted by Andy238 View Post

Should there be such a concern about headroom under a soffit? I mean, how often do you walk around the perimeter of your theater right next to the wall? Just wondering aloud...

I think it just looks nicer and opens up the room.
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post #24 of 41 Old 05-22-2008, 12:28 PM
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Quote:
Originally Posted by Andy238 View Post

Should there be such a concern about headroom under a soffit? I mean, how often do you walk around the perimeter of your theater right next to the wall? Just wondering aloud...

My soffit is 31.5" wide and extends over the door into the room, so for some of us it's pretty important. If you have a 12" soffit or somethign similar, I'd agree that the height isn't critical.
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post #25 of 41 Old 05-22-2008, 12:46 PM
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Ahhh, good points.
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post #26 of 41 Old 05-22-2008, 07:50 PM
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Here is a pic of how I did it, dc04 decouple the main wall sill plate from the I beam, then hooked to rsic-1 clips, every 16.




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post #27 of 41 Old 05-23-2008, 01:54 PM
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Hey Joe. Looking good.

Did you assemble the soffit first and then lift into place?.

Also. Don't forget to put your insulation in that cavity. I would imagine it wouldn't be that hard to put it in as you do your soffit sections. Be careful not to over compress as that may result in coupling.

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post #28 of 41 Old 07-03-2008, 06:55 AM
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When you guys used the dc04 to decouple the wall from the i-beam - did you actually drill into the i-beam to get that part of the clip to mount?

I have to build a soffit around some duct work, but there's an i-beam that I'll have to work with, and I was just wondering how you guys attached the wall to the i-beam.

Sorry, I don't have a pic.

Thanks,
Scott
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post #29 of 41 Old 07-03-2008, 09:51 AM
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post #30 of 41 Old 07-03-2008, 10:39 AM
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WOW!

Thanks for posting!
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