# Hoosier Home Theater - just getting started



## donlino (Aug 21, 2009)

Hello all, I have finally decided to move forward and build a dedicated home theater room in my basement. Here is some general info:

Width: 13 '
Length: approx 24' 8"
Ceiling is 8'4" in main area and 7'4" in entrance area
Entrance will be to the rear on the right 
leather couch 1st row
2nd row will have 5 Berkline powered recliners (45004s) with mini-Buttkickers and lighted cupholders
8"? riser for recliners
106" Grey Wolf II Screen (1.8 gain)
Optoma HD70 Projector
Infinity Beta 50s Front L & R
Infinity Beta C360 Center
Haven't decided on 5.1 or 7.1 
Velodyne CT120 sub and Klipsch 8" sub
Also haven't purchased surrounds yet but may purchase Infinity Classia C255ES to help match to existing speakers.
I am thinking about installing a subfloor on top of the concrete flor and may use Dricore (does anyone think this will help isolate the sound?)
Ceiling is already drywalled but plan on adding 2nd sheet of 5/8" with Green Glue. I think I will also blow in insulation above the 1st layer of drywall on the ceiling.
Left wall and rear wall will be double wall construction with 2 sheets of 5/8" on each with Green Glue in between the sheets. 1" air gap between the walls. R13? unfaced insulation in each wall. 
Should I also use mass loaded vynil?
I plan on using acoustic caulk on the first layer of drywall since I don't think I need to tape and mud the first layer. Will also use the caulk at top and bottom of walls. Does first layer go on horizontally and 2nd vertically?
Front wall and right wall are already drywalled. There is concrete foundation wall behind these two walls. Assume not necessary to add 2nd layer to these?
I am thinking of using the plastic insulating stuff that builders use for sill plates under and above the 2'x4' plates to help isolate the top and bottom of the left and rear wall.
Would like to install 4" airtight can lights along the sides of the walls but concerned about sound escaping. 
The area currently has 2 HVAC supplies but no returns. I am very concerned about sound travelling throughout the house via the ducts so may rip open existing ceiling drywall to either use flex duct or install some type of silencer?? 
Thinking of having cabinets built for front which will also frame around my pull down screen. Equipment would go in top left cabinet covered by door, all speakers would go in cabinet and would of course have speaker cloth in front of them. I believe I should put sand in the base of the cabinets to help with the acoustics. Also would put insulation in the riser for the recliners. I have 2 subs one Velodyne front firing and 1 Klipsch down firing (assume it would be ok to also put these next to the left and right speakers in the front cabinet?)
I am also thinking of putting in a counter behind the recliners with some bar stools but not sure.
There are 2 electrical panels in the front right wall which I will have to work around (currently covered by the white cabinet you see in the pic). You will also see that there is a bar/kitchen area behind the home theater area that I also plan on remodeling to help make the basment more of a man cave.

I don't know how to use any of the design software so I am attaching my sketch made in Excel. Also attaching pics of the before. I had built a temporary riser which you will see in the pics. I welcome your thoughts and suggestions to help me build out my home theater so I can crank the movies without having my wife yell anymore! Thank you.


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## Ted White (May 4, 2009)

Wow. Plenty of questions. If you have concerns about sound leaking into the rest of the house, then you'll need to consider all surfaces. Floor won't acoustically benefit from the Dricore, though it may be cozier.


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## bpape (Sep 14, 2006)

Agreed. It'll be warmer and give you a little more feel. It will help a tiny bit in reducing flanking through the slab but not a lot. If you were to build walls on top of the Dri Cor, that can help.

The cans are defnitely an issue unless you build back-boxes behind them all. You'll need to do the same for switches, outlets, etc. Also, don't forget HVAC.

Bryan


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## Ted White (May 4, 2009)

I would only ever recommend that the wall is framed to the slab, sealed with a sealant to the slab and then drywalled before any floor treatments, stages risers, etc are built.


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## bpape (Sep 14, 2006)

Difference of opinion. I do walls on top of subfloors like that all the time for a little extra decoupling. Yes - we still use sill gasket under the walls and seal the walls to the floor.

Doing the walls direct to the floor, sealing, and floating a floor in the middle will work too.

Bryan


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## Ted White (May 4, 2009)

The way to view it is that a larger gap / opening will require more mass. Small cracks can be handled with sealant, but Dricore is 7/8" and that's just huge.

So the best gap is no gap. Foams under walls have no mass and aren't sealants.

The wall won't vibrate that floor, and the floor won't vibrate that wall, so decoupling really offers no demonstrable benefit.

The Dricore is relatively low mass so safe to say that it won't shield the floor from anything. It does have little dimples underneath and that air cavity created is not a great thing. Not sure what the resonance point might be, but likely too high to approach the coincidence point of that slab.


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## bpape (Sep 14, 2006)

Agreed the foam isn't massive. It's purely an air thing. That's why we still caulk on both sides of the base plate of the wall. 

I'd agree that the resonance is way above the conincidence point. 

As for it helping, I just look at it from a practical standpoint. I've heard what it does and IMO it does provide a small benefit for basically no more money over floating the wall inside.

I understand your point about the 7/8" 'gap' underneath. 

Bryan


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## Ted White (May 4, 2009)

Curious is the wall is resting on the 7/8" Dricore, how do you seal the backside of the bottom plate where the 7/8" gap is?


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## bpape (Sep 14, 2006)

The rear of the bottom plate is just inside the edge of the Dricore. It's caulked just like the front side is. No 7/8" gap between wall and Dri Cor.

Bryan


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## Ted White (May 4, 2009)

Ah, OK. So just the "open" edge of the Dricore is exposed on the other side?


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## bpape (Sep 14, 2006)

Yes - that's correct. If we can, we run it to within 1/4" (depending on temp changes in the area) of the foundation or outer wall where possible and caulk that edge too.

Bryan


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## donlino (Aug 21, 2009)

This is helpful. I was only planning on installing the Dricore subfloor becasue I thought it would be helfpul in decoupling the room and would help keep the bass in the room. I don't have any issues with a cold floor so sounds like I can omit the plan for the subfloor. Is there any decoupling benefit in installing a subfloor in a home theater room that is built in basement with a concrete slab or this only appropriate on 1st or 2nd floors that are built on wood? Or would I need to build a traditional floated subfloor with 2x2s, insulation, plywod etc. to achieve any real decoupling for my room since it's over concrete? Also, is there any benfit in using a sill gasket above the top plate of the walls to help decouple them from the ceiling since my ceiling is already drywalled? (I do plan on adding a second 5/8" sheet to the ceiling with Green Glue but same issue applies the top plate of the wall will still be in contact with 2nd new sheet). Thanks!


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## Ted White (May 4, 2009)

donlino said:


> Is there any decoupling benefit in installing a subfloor in a home theater room that is built in basement with a concrete slab
> 
> No
> 
> ...


Not necessary


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## donlino (Aug 21, 2009)

Got it makes sense. Will I have a weak link in my decoupling if I don't do anything to treat the right and front walls of the room that are already drywalled? The concrete foundation sits behind them. The option as I see it is to add a second sheet of drywall (5/8") to the front and right walls with Green Glue in between. My guess is the builder used 1/2" on the existing front and right walls even though I would be building the new left and back double walls each with 2 layers of 5/8", hopefully that won't screw up the acoustics. As for my ceiling is the best approach to blow in insulation above the existing 5/8" drywall and then Green Glue followed by new 5/8" drywall sheet? Is there a better approach such as putting the new sheets on furring strips below the existing ceiling (although that would decrease headroom)? Would appreciate your thoughts.


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## Ted White (May 4, 2009)

Would you know if the wall framing is spaced from the concrete? Or is the framing pushed right up to the foundation?

R19 Batt insulation in joists is great. R13 in walls.

You would not use clips, furring or spacers on any kind on existing drywall. The small air cavity will cause big problems.


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## donlino (Aug 21, 2009)

I will check later today. I think there is a smaill space between the studs and the foundation wall but probably not much. I don't think I can use batts in the ceiling since it's already drywalled with one sheet so I believe my only option is to poke holes and blow-in insulation. Should I try to completely fill the cavity or leave an air gap?


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## Ted White (May 4, 2009)

A small space between the studs and foundation is all you need to have those walls officially decoupled. So you can just add drywall to the existing walls.

Go for a light density application of cellulose. This stuff is often over-packed and then starts conducting vibration. There's no advantage per say to leave an air cavity other than it ensures no over-compaction.


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## donlino (Aug 21, 2009)

Ted, you indicated that I should just add drywall to tthe existing walls (front & right walls) but I thought a second sheet on those walls is not necessary since they are in front of the concrete foundation walls. Can you please clarify?


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## Ted White (May 4, 2009)

We're not concerned about sound exiting through the concrete into the dirt. We are, however, concerned about sound passing through single drywall and headed straight up into your floor joists. Common flanking path.


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## donlino (Aug 21, 2009)

Has anyone installed backer boxes for can lights in a ceiling that's already drywalled? Just curious if the degree of difficulty increases substantially as a result of the existing drywall. Also, is the best approach to use acoustic caulk on the first layer of drywall for my double wall construction or should I just tape and mud the first wall? Thanks.


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## Ted White (May 4, 2009)

I do not believe it is at all practical to build a backer box through the small hole in the ceiling.

I would rely on sealant on the first layer. No need to do the mud and tape on first layer.


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## donlino (Aug 21, 2009)

To clarify, I currently do not have can lights where I plan on putting the home theater room. I actually have 2 ceiling fans in that space that will need to come down. I will have to install the cans and in this case will also need to install the backer boxes with the cans by cutting rather large openings from what I can see. Seems like a lot of work given the existing drywall ceiling.


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## Ted White (May 4, 2009)

You can certainly cut out drywall to accomodate a box. Also, it would be easier all around if you stick with some of the new fixtures from Halo, etc. Their 3-4" cans mean less flanking issues.


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## sandbag (Aug 2, 2009)

Ted and others suggested removing the ceiling drywall (granted, a mess) from the existing joists, addressing all sound flank issues while you have the ceiling open, then hanging new joists in the existing joist space but dropped down at least an inch or more for true decoupling, insulating above the new joists being certain not to over compress the insulation, adding additional insulation between the new joists, then creating a new 5/8" + GG + 5/8" ceiling attached to the new joists. This way you get a minimal ceiling drop, a decoupled higher mass ceiling, insulation and the knowledge of what lurks between the two leafs of that presently mysterious floor/ceiling. You can probably downsize the joist web dimension by 2" from the present combo floor/ceiling joists, since you will have no floor loads to support. FYI - In my case, I'm supporting the new joists on beams so as to avoid coupling them to the existing walls. Probably not necessary. I'm even planning on green gluing a layer of drywall to the exposed subfloor, above and spaced apart from the top edge of the new joists, since I have only 3/4" plywood floor decking, and want more mass. I may even add more, depending on the frustration factor. The weight will be about the same as the drywall removed from the existing ceiling. I'll be losing torsional resistance. After removing the ceiling drywall, I'll bounce on the floor above a few times to see if it moves much more. 
I have been warned not to create a third resonating leaf as would be the case in your furring strip approach. Good luck - there are a lot of good suggestions to be had for the asking.


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## Ted White (May 4, 2009)

Sounds like the plan, Sandbag.


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## donlino (Aug 21, 2009)

Sandbag I will not be applying furring strips to the existing drywalled ceiling. I would simply blow in insulation above the existing drywall, apply green glue then apply new 5/8" drywall. I'm not sure but the builder may have installed furring strips directly to the joists and then installed the drywall but I don't think this creates a triple leaf effect? Will I have a triple leaf situation be installing new drywall to the existing drywall (with green glue in the middle)?


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## Ted White (May 4, 2009)

If there are furring strips on the joists, then there is no triple leaf. If you were to apply furring to the existing drywall, you would have a triple leaf and the entire system would suffer considerably.


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## bpape (Sep 14, 2006)

Correct. It's all a matter of where the iso is and where the mass is. 

Bryan


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## donlino (Aug 21, 2009)

quick update, I cleared out the area, pulled the carpet out and decided that I will remove the existing drywall ceiling. Given my change in plans regarding the ceiling, I will need to research my options for isolating the ceiling. specifically if it's feasible to install new joists and lower the ceiling slightly so it is decoupled from the floor above.


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## donlino (Aug 21, 2009)

My existing floor joists run from left to right across the width of the room. If I float the new joists unfortunatley I can't rest them on any new walls since the top foot of my left wall is already built. The top of the left wall is a box around my hvac that runs through the middle of my basment. The right wall is already drywalled so all I was going to do was add 2nd sheet. what would I attach my floating joist to achieve effective decoupling? Would it be ok to attach it to the same rim joist as the existing joists? would decoupling occur as long as the floating joists don't touch the floor above? hope that makes sense.


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## bpape (Sep 14, 2006)

It would help some as the rim joists are pretty well damped and under load. You could also use RSIC-1 clips or Whisper Clips to just isolate the drywall from the existing joists.

Bryan


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## sandbag (Aug 2, 2009)

That's a great question. Of course it will be coupled at the rim joist, and likely through it up through any upstairs wall resting on it, and of course along and out through the existing joists to the floor. How much will this be? Far less than your present direct coupled floor/ceiling, which is an undamped drumhead that builds resonances rather than defeating them. I'm assuming you have 2"x10"-12" lumber joists spaced 16" o/c on a 3.5" stud wall in the following comments (if you have open web steel tresses or other good but different stuff up there, let us know): 

I'm for ease of construction plus caulk. You'll be space challenged if you try to use the existing rim joists, because you'd be inserting an equivalent length joist into a 3.5" deep, 14.5" space over the sill plates. Plan on the new joists being 3.5" or so shorter than the total rim joist to rim joist dimension to enable you to put them in place. To minimize loss of ceiling height you will probably want to notch (aargh!) the new joists to ride an inch or so lower than the existing ceiling. A perimeter ledger for securing the new drywall edge might be helpful, and help level the new ceiling better than blocks between studs. You can buy half-saddle joist hangers to hang from the top of the sill, but the top edge will still be whippy. 
Note: the experts say to leave a caulk gap between wall/ceiling drywall junctions.
I'd cut the new joists shorter and stabilize them with blocking, leaving plenty of movement room for the existing joists. Depends a lot on your framing skills, whether you will go with soffits (room to fudge), and how much actual space you'll have to work in. If you'll use a framing nailer, will it fit where you need it to fit? If a screw gun, how long is your gun + bit + screw?

None of this is insurmountable. Consider plywood, screws, and glue to strengthen your notches. Stabilize the new joists, somehow. Don't forget to insulate the air pockets. And, think like a boat hull builder -- where can water seep through? -- sound leaks are even more insidious. 

But mainly, have fun and take many photos. Before and after sound pressure levels would be a great boon to all of us who prefer data over anecdote.

Hey, Tom "data over anecdote" is that slick or what?


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## Ted White (May 4, 2009)

http://www.soundproofingcompany.com/library/articles/room_within_a_room/

Floating ceiling construction discussion. If not practical, clips are the next best thing.


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## donlino (Aug 21, 2009)

Something came up today that I hadn't given much thought to up to now. I have a lally column that supports an I beam that will be inside my left double stud wall. I can probably notch the plates so they don't actually touch it but not sure best approach in order to try to decouple it from HT room. Only option I see is to wrap it with some type of pipe wrap product similar to MLV? Will I really be able to achieve my goal of noise isolation with this column in my wall? I feel like I'm trying to make some progress but keep running into obstacles. Any suggestions? i will try to post some pics later tonight.


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## Ted White (May 4, 2009)

donlino said:


> I can probably notch the plates so they don't actually touch it but not sure best approach in order to try to decouple it from HT room.


This is it pure and simple. Bury it with no contact. Pics would be great.


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## donlino (Aug 21, 2009)

Ok here are some pics of the room and the lally column. The area to the left painted dark blue is where I was originally going to put the home theater room but decided against it since the main HVAC ducts drop the ceiling a foot from 8'4" down to 7'4". Based on my rough measurements the column will affect the second wall. Will wrapping it with MLV also help?


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## Ted White (May 4, 2009)

donlino said:


> Will wrapping it with MLV also help?


It would technically help. Not sure how much. This structure would be most sensitive to impact noise, and there won't be any impact to the column if buried in a wall. So I would skip the MLV and wraps


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## donlino (Aug 21, 2009)

Thanks Ted. As you can see, the top plate of my left double walls will touch the drywall soffit of the box that frames the HVAC ducts and the I beam. Should I put some type of thick rubber material on top of the the top plates to help decouple each of the those walls from the drywall soffit? Another alternative would be to add a 2nd piece of 5/8" drywall with GG in between the two sheets. Or is neither necessary? My plan is to have the 2nd drywall sheet on the inside of my HT room go up against the existing fascia so that there are 2 layers on that part of the wall. The 1st drywall sheet on the inside of the room would only run up to the drywall soffit.


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## Ted White (May 4, 2009)

Obviously the idea is to have the inner wall contact as little of the original framing as possible. You (ideally) would not want to contact that soffit at all


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## seattle_ice (Jul 12, 2006)

Be very careful with building backer boxes around recessed cans. If you make them too tight, or the cans are the wrong type, it can be a serious fire hazard. Make sure to use good, high quality lights like Halo or Juno, and make sure they are IC rated.


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## donlino (Aug 21, 2009)

Would you recommend using the RSIC DCO4 clips to keep the top plate of the inner wall from touching the soffit? Even if I do that the second drywall sheet on the inner wall will still come in contact with the fascia of the HVAC box albeit there will be GG in between the sheets. Does one negate the other? What about the outer wall, would you recommend the RSIC DCO4 clips for that as well? This is challenging to say the least.


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## donlino (Aug 21, 2009)

I've ripped out the drywall ceiling and also removed some of the drywall that runs on the right wall that covers one of the two I beams that are in my room. The other I beam is on the left side of the room. Now that the ceiling is down, I will remove the existing round metal HVAC ducts that run across the width of the ceiling and replace with either insulated flex duct or duct board. Is one better than the other? 

With respect to the ceiling I can either try to (i) put in new floating joists (although that may be difficult given that my builder used traditionl joists with the cross braces) or (ii) use hat channels and clips. I may go with a coffered ceiling after I put up the two 5/8" sheets of drywall w/ GG. If so any idea if the hat channles/clips could support the weight? 

I don't think there is much I can do with my two existing walls (front and right). One idea I had was to decouple their top plates from the joists by removing top portion of drywall, shortening them and then attaching clips to isolate the from the joists. Seems like a lot of work. Any thoughts on whether the bulk of the sound escapes via ceiling or walls? Thanks to all for your input thus far. Here are the pics.


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## Ted White (May 4, 2009)

Nice pic array. Nice space. You're likely going to need clips for the reasons mentioned. You'd build a soffit that hung on it's own dedicated clip + channel.


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