[storman]

I have a question or two about constructing a soffit in my upcoming HT. I want to minimize sound xfer to floor above, so I plan to decouple the HT ceiling with RSIC clips + hat channel - double layer of 5/8" drywall. So the question is - do I have the soffit framed out before or after the ceiling is drywalled ? If afterward, wouldn't we have to avoid screwing / nailing the ladder frame to the joists to avoid what Dennis would call a short- circuit ? But I can't imagine putting up the soffit framing without attaching it to something more secure than drywall.


Thanks,

Bill

 

[Kevin_Wadsworth]

Soffit is pretty light and could be attached with drywall anchors. I plan on doing this on one soffit across the back of my room that will serve as a bass trap.


For soffits hiding beams/HVAC/etc. (the other 3 soffits, in my case) you want those on the "outside" of the room anyway to help with the sound minimization. So you would construct those prior to drywall.

 

[tlogan6797]

Good question as I am at this exact stage right now. I was told by an inspector that, although my 2 HAVC runs and return were "fine," if I am going to drywall the ceiling I have to frame the soffits before he can pass it. So here's what I plan to do: Build the "ladders" and hang them from the DC-04 clips (same as I am using on the top plates of the stud walls. I'll attach the metal side to the side of the joist (with the top of the ladder attached through the neoprene (or whatever it is) grommet, and just enough clearance for the top of the "ladder" to clear the bottom of the joist. Then for the side that attaches to the wall, I'll run a ledger board along the wall (across the studs) and nail the bottom "rungs" from the "ladder" hanging off the clips to the ledger board. Because the stud walls are decoupled, this should decouple the soffits from the joists.


So the other question is what size lumber to use for the "ladders?" I was planning on 2X2 top and bottom plates with 2X4s turned sideways for the rungs and across the bottom.


Tom

 

[Winkelmann]

My soffits will be made of MDF and will be used primarily to house my recessed lights. After the walls go up, I plan on screwing anchoring strips (through the wallboard) to the studs.

 

[Texas Aggie]

How do you intend to cover the seems in the MDF pieces? GOM cloth?


If not GOM, how?


thx

 

[Andy238]

Hey, I just completed framing all my walls and I'm in the same "soffit" quandry!


I used DC-04's on the top plates of the walls to decouple them from the joists above. For the soffit I'm thinking I'm going to use the RSIC-1 clips & hat channel and hang the "top of the ladder" of soffit frame from it.


I'm just trying to figure if I should do it before or after drywall too. Maybe I should ask my inspector. I've seen folks use 2x2 for the whole soffit frame. I'm just worried about finding ones that are straight enough.


Then comes the question of the columns. Since I want to put power outlets in the columns I think I need to put those in before drywall as well. Ya think?


Andy

 

[tlogan6797]



Quote:
use 2x2 for the whole soffit frame. I'm just worried about finding ones that are straight enough.

I ripped mine from 2X6's because I wanted 12 footers. They look pretty good to me.


Tom

 

[Kevin_Wadsworth]



Quote:
Originally Posted by Andy238 /forum/post/0


Then comes the question of the columns. Since I want to put power outlets in the columns I think I need to put those in before drywall as well. Ya think?

It would depend on the inspector (if your having it inspected). I would think they would like that, but putting the columns in first defeats a lot of the sound -isolating principals that people on this forum try to adhere to.


I would think an acceptable alternative would be to drywall before the columns and put a receptacle in the wall or soffit where the column will go. Either leave enough spare wire that you can pull it through this box into the receptacle that will be on the column or turn that box into a junction box and splice to another piece of wire that will go to the final destination.

 

[dhnjp1]



Quote:
Originally Posted by Texas Aggie /forum/post/0


How do you intend to cover the seems in the MDF pieces? GOM cloth?


If not GOM, how?

I just finished doing this myself last week. After hanging the sofits, I glued and nailed all the 1" firring strips on the bottom to lock the sections together (bottom will be covered with Linacoustic/GOM, front is painted). Then I filled all the visible seams and screw holes with Bondo. After sanding smooth, it took paint beautifully and nobody will ever know where the seams were.


--Dan

 

[Don_Kellogg]

Drywall on RSIC clips first then soffits. Have a look at John Kotches Constrution thread. Thats how his went from what I remember.


I did mine that way I also used RSIC hangers. I really don't hear anything from upstairs. But I also put LIN acoustic on the under side of the floor in the joist space followed by R38.

 

[Texas Aggie]

I tried the bondo last time and it....was...um...visable...


I quess I will try it again in my new HT.


If I hade the choice(which I do) should I just hae the builder do the ceilings with the soffits


OR


Build the room "squared out" and then go back in to do the soffits with MDF?



I am leaning towards the squared method so my GGlue install goes smoothly. The more corners seems to lend itself to more error possibility.

 

[Andy238]



Quote:
Originally Posted by Kevin_Wadsworth /forum/post/0


It would depend on the inspector (if your having it inspected).

I did pull permits so that is why I thought that columns might have to go in first.

Quote:
Originally Posted by Kevin_Wadsworth /forum/post/0


I would think they would like that, but putting the columns in first defeats a lot of the sound -isolating principals that people on this forum try to adhere to.....

Yes and no. The columns are still attached to de-coupled walls & ceiling, they will be double drywalled, and stuffed with insulation. So I think they'll be not too different than my walls as far as isolation goes. I know that many folks do the drywall first and if I can, I'll do the same.

 

[Andy238]



Quote:
Originally Posted by tlogan6797 /forum/post/0


I ripped mine from 2X6's because I wanted 12 footers. They look pretty good to me.


Tom

Good idea. I didn't think of that. Thanks!

 

[Winkelmann]



Quote:
Originally Posted by Texas Aggie /forum/post/0


How do you intend to cover the seems in the MDF pieces? GOM cloth?


If not GOM, how?


thx

I still haven't locked on one design. Though I was thinking of mitering the edges or trimming them out. No GOM for the soffits, I'll put a spray finish on them.


P.S. MDF is available in trim lengths, the longest I've seen was sixteen feet.

 

[storman]



Quote:
Originally Posted by Don_Kellogg /forum/post/0


Drywall on RSIC clips first then soffits. Have a look at John Kotches Constrution thread. Thats how his went from what I remember.


I did mine that way I also used RSIC hangers. I really don't hear anything from upstairs. But I also put LIN acoustic on the under side of the floor in the joist space followed by R38.

Thanks Don. Ques tion - what are RSIC hangers ? I assume they are different from the RSIC -1 clips ? I also see a few of the respondents mentioned a product called DC-04. Is that another type of hanger from PAC International ?


I'm wondering if I'll be able to do it in this order ( rock the ceiling, then add soffits ).

I plan to have some recessed lights and/or rope lighting in the soffit. I'm contracting out all the work, so each sub will come out once; the framers, then the HVAC and electical and plumbing, then drywall, and so on. Therefore, the soffits will have to be framed and in place prior to when the electrical and drywall crews arrive. The best plan in my situation may be to use isolation clips or attach the soffit directly to isolated wall framing. The main concern here is to keep this basement HT room decoupled from the floor joists of the 1st floor of our house.


Also, I'd like to know approximate cost of these clips and hangers so I can get a feel for how much this will add to the construction costs. I think there might be a forum rule against that, so you can PM me.


Bill

 

[Kevin_Wadsworth]

I believe when he says RSIC hangers he means the RSIC-1 clips.


DC04's are also on the PAC website - they are used at the top of the wall to attach it to the floor joists instead of just nailing the top plate. There w as a thread a while back debating whether this made any improvement in sound transmission. To my knowledge, there are no lab data, but I think the consensus was that it couldn't hurt.


For pricing, both types of clips run somewhere around $5 per clip, so they aren't particularly cheap.

 

[McCall]

Mine went in a preexisting room on the ceiling, used square frames of 2/4 fastened to wall and ceiling framing and sheathed in MDF it is very heavy. inside is conduit for speaker cable and the rest is stuffed with fiberglass insulation.

 

[Andy238]

Bill,

Here is a site that sells RSIC products online. There are a couple guys here on the forum who also sell them ( I can't rememer who, sorry). Do a search for RSIC and see what you can find.


As Kevin said, they aren't cheap. I needed about 75 RSIC-1's for the ceiling and soffit supports. I wound up getting 100 clips since that was the price break point. Fortunately I didn't need that many DC-04 clips for attaching the wall top plate to the joists though and those were close to $7.00 each! Ouch.


Here are a couple photo's of the DC-04's installed.

 

[tlogan6797]



Quote:
As Kevin said, they aren't cheap. I needed about 75 RSIC-1's for the ceiling and soffit supports. I wound up getting 100 clips since that was the price break point. Fortunately I didn't need that many DC-04 clips for attaching the wall top plate to the joists though and those were close to $7.00 each! Ouch.

Our rooms must be about the same size. I bought 100 of each because I was afraid that if I bought fewer and needed more, they would be a lot more expensive without the price break and then have to pay shipping again. I'm thinking that I can probably sell off what I have left over. I have ruined a couple trying to drive them into my poured concrete wall with a ramset.


Tom

 

[Andy238]

My room is 13x24 plus a snack bar area off the side at about 7x5.

Well I guess I don't have to ask if you want to buy any RSIC clips