# Theater construction questions



## Kevinicus (Sep 11, 2014)

I am about to start work on my basement theater soon, and I want to make sure I do things right, and there are some aspects I am unsure of.

HVAC: This is probably the thing I understand the least about what the issues really are. I know there needs to be steps to limit the sound from the system, and that the proper airflow and temperature is in the room, but when it gets to the details I'm completely lost. My room will not have complete sound isolation, so I know it shouldn't be as complex as others, but I still want to limit sound and keep the temperature nice. What are the big issues I need to look for, and what methods does the contractor need to use to accomplish them usually?

Stage/Riser: I know that leaving a gap between the wall is recommended for decoupling, but what I want to know is what is used to cover/fill the gap so that it's not seen? Does carpet usually fill it? Or base boards/molding? Also, how exactly does the screen wall attach with clips? Are the clips screwed into the studs/joists and attached to the false wall frame? Minimalist approach to the wall is best, right?

What are the typical layers used for the stage and riser? Should they be built on top of some layer that decouples them from the floor?

How do the panels that cover the false wall usually attach?

Insulation: What kind of insulation in the walls and ceiling should be used when there won't be complete sound isolation? Regular fiber glass? Foam? Roxul? 

Electrical: I am planning at least 3 20A circuits (2 for subs, 1 for equipment), should I have another for lights? Should the projector be on it's own circuit?

I'm sure I have a lot of other questions, but those are the big ones pressing on my mind right now. Any other major things to look out for, feel free to inform me. Any help at all is very much appreciated! Thanks. I've included some pictures of what I have to work with. I tore down the ceiling this past weekend, so you can see the current ducting. 

This is the layout I'm looking at after I construct/extend a couple walls:



I do plan to push back the wall on the right back to the I-beam to make it a little wider. Here are various pictures around the room.















I'm also concerned about closing off the area at the bottom of the stairs and adding a door there. I'm afraid it will limit the size of anything I can bring in or out of the basement once it's put in. Here's that area:


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## rambocommando (Aug 28, 2014)

I'm just going to touch on the parts that I am knowledgeable enough to talk about. The best advice I can give you is to go through theater build threads, on this forum, on other forums, wherever you can find them. Just read through the thread, see what mistakes or changes someone else made. Its always best to learn from other peoples' mistakes, and cheaper too 

The risers being decoupled from the rest of the room is unnecessary. You would want the drywall to be decoupled from the studs (using clips/hat track) to prevent sound coming in or going out. There isn't really a benefit to keeping the risers decoupled from the rest of the room. Being in the basement the sounds will only travel up or horizontally. If you build the riser after the room is drywalled, and the drywall is decoupled, then you are good to go. I wouldn't worry about decoupling from the basement floor.

For insulation, I would recommend Roxul. You might not have complete sound isolation, but cutting down as much outside sound as you can is essential. Insulation is a good bang for your buck way of lowering it. 

For building a stage/frontwall, generally people build a simple frame "stud wall" with 2x2s and maybe a set of 2x4 directly behind where the screen will be mounted. You would then attach the screen mounting hardware to the 2x4s and attach the screen that way. The rest of the wall would be made up of acoustically transparent material stretched over frames of 2x2 and stapled (think painting canvas stretched on a frame). Those panels are then attached as you see fit.


As for bringing things in, you'll want to get measurement on the furniture that you plan on buying. Don't assume that it will fit because you need it to. Especially if you are planning on getting rows of 3 or 4 seats as one unit.

The thing I notice about your setup is that you'll have to pay attention to the ceiling height for the projector, and the height the back row will be at on risers. Also, the back row against the wall isn't an ideal location, ideally you would have 5 feet or so behind your back row, but we all have space constraints


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## Kevinicus (Sep 11, 2014)

Yeah, the walls aren't going to be decoupled. It's not in the budget, and as far as the ceiling goes, it's already low enough as it is, so that would just make it worse. I had heard decoupling the riser if possible is the way to to it, especially if the walls aren't decoupled, and also if there might be buttkickers at some point. The stage of course will be more important to decouple with subs.

As for the stage wall, I'm more curious as how it is supposed to be supported if it's not going to be attached to the walls. Clips, I understand can be used, but how are they attached after drywall is up?

I'm worried about a sofa I'd bring in for the room off to the side. I can get it in now before any construction is done, but once that wall is finished, I think it would be very difficult to get back out if I wanted to. The theater seating I'm not worried about since the backs come off.

The projector will be above the back row of seating, but above the actual seats, not the area anyone would stand on the riser. And there will be about 3' behind the back row. The black outline on my layout is soffit area.


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## Kevinicus (Sep 11, 2014)

Well, the first HVAC guy was out today. I'm not sure he understood the theater aspect of things (not that I really do either). He was talking about putting the return low towards the floor to keep the warmer air down. He seemed to be thinking of ways to keep the theater warm in the winter. He wasn't concerned about it getting warm in there because it was a basement and they tend to stay cool. I mentioned the projector/people generating heat, but he didn't seem to think much of it. 

I asked about not having the theater connected to the same trunk as other rooms, but again he didn't seem concerned, and/or didn't see a way of doing it. He wants to branch off two supplies from a main trunk to put in front of the screen. I am wondering if they can be ran through the soffit I'm going to build along the side, but I do want to have lights in the soffit too, and I'm not sure it would fit. 

Basically he wanted to do 2 supplies like I mentioned, a return low at the back that would use insulated flex ducting and something else about having another vent for combustion air going into the mechanical room (he said this could be done a lot of different ways).

I really don't know if what he was talking about would be right for the theater or not, but he indicated it would be about $500.

Is this guy way off, or making sense with what he's saying?


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## jtl (Sep 19, 2013)

Going to be a great room when finished.


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## NBPk402 (Feb 21, 2012)

You can run your HVAC ducts in a soffit, and have lights... Just make them big enough. Our soffits are 1' tall by 2' wide with LED lights in them. Our lights only take up maybe an inch or 2 max of the depth, and are similar to these except ours are round.


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## Kevinicus (Sep 11, 2014)

ellisr63 said:


> You can run your HVAC ducts in a soffit, and have lights... Just make them big enough. Our soffits are 1' tall by 2' wide with LED lights in them. Our lights only take up maybe an inch or 2 max of the depth, and are similar to these except ours are round.


I definitely can't do soffits that large. I was looking at doing maybe 9" tall by 18" wide or so. I'm not sure how large the ducting pipe would be. Those lights look like they hardly take any space at all. How well do the light?


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## NBPk402 (Feb 21, 2012)

Kevinicus said:


> I definitely can't do soffits that large. I was looking at doing maybe 9" tall by 18" wide or so. I'm not sure how large the ducting pipe would be. Those lights look like they hardly take any space at all. How well do the light?


 The light I purchased were the lowest wattage ones they had (I think they were like 4w)... They had brighter ones that were exactly the same size. We have them about 6' apart and they are nice. We only have them in the soffits, so they don't really light up the room 100% but it is enough for my purposes.

I think you might be able to run 6" flex ducting in your soffits... As long as the soffits are wider than in one direction you should have enough room for the lighting.:T


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## Kevinicus (Sep 11, 2014)

ellisr63 said:


> The light I purchased were the lowest wattage ones they had (I think they were like 4w)... They had brighter ones that were exactly the same size. We have them about 6' apart and they are nice. We only have them in the soffits, so they don't really light up the room 100% but it is enough for my purposes.
> 
> I think you might be able to run 6" flex ducting in your soffits... As long as the soffits are wider than in one direction you should have enough room for the lighting.:T


So, you're saying that there's a chance?


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## NBPk402 (Feb 21, 2012)

Kevinicus said:


> So, you're saying that there's a chance?


Yes, just find out what the outer dimension is for the flex you want to use, and make sure the soffit is at least that size. I would also try to leave a couple of inches or so for your lights... If you make the soffit wider than the ducting you will have plenty of clearance for your lighting as long as you don't mind it being closer to the edge of the soffit. Another option you have is to use something similar to  these... Just attach them to the underside of your soffits.


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## Tonto (Jun 30, 2007)

You don't want the HVAC coming straight into the room. You want it to turn, then turn again into the room. This will cut down on the sound traveling into the rest of the house via that duct. It will also help to put some insulation at each turn for absorbtion.

It wont hurt to use isolation clips on the riser. Doing so will help with the tactile responce felt in the chairs. Remember to cut holes in the front of each section & in the top/back of each section. Stuff each section with fluffy insulation. Bass will enter each section, some will be absorbed, some will exit the rear. You will feel it in the chair a little bit.


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## Kevinicus (Sep 11, 2014)

Tonto said:


> You don't want the HVAC coming straight into the room. You want it to turn, then turn again into the room. This will cut down on the sound traveling into the rest of the house via that duct. It will also help to put some insulation at each turn for absorbtion.
> 
> It wont hurt to use isolation clips on the riser. Doing so will help with the tactile responce felt in the chairs. Remember to cut holes in the front of each section & in the top/back of each section. Stuff each section with fluffy insulation. Bass will enter each section, some will be absorbed, some will exit the rear. You will feel it in the chair a little bit.


Could you elaborate a little more on what you mean by putting holes in the front and back of each section?


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## NBPk402 (Feb 21, 2012)

Kevinicus said:


> Could you elaborate a little more on what you mean by putting holes in the front and back of each section?


I believe he is referring to it being used also as a bass trap.


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## Tonto (Jun 30, 2007)

Sure, as you place your joists down for the plywood to be nailed/screwed onto (plan spacing to match insulation width). Depending on what you face the riser with (solid vs other) is the basis for proceding. My riser is 10" high (used 2x10's spaced 16" apart). I ripped a 2x6, notched the front of each joist (top & bottom) & ran them (the 2x3's) along the top & bottom (across the front), leaving the middles open. At the rear of my riser, I cut rectangles out of the plywood deck (one for each section) & used AC floor vents so you wouldn't put you foot through the hole.

If you use a solid board for the front (a 2x10 in my case), you would use a hole saw & punch some holes into the board in each section & again in the top/rear of the riser as I did.

And yes, this helps with bass trapping as well as a bit of increased tactile responce. It just doesn't make sence to waste the space!


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## Owen Bartley (Oct 18, 2006)

Kevinicus said:


> So, you're saying that there's a chance?


LOL at your Dumb & Dumber quote. 

Kevin, maybe a visual would help. Holes at the front of your riser could look something like this:


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## Kevinicus (Sep 11, 2014)

Owen Bartley said:


> LOL at your Dumb & Dumber quote.
> 
> Kevin, maybe a visual would help. Holes at the front of your riser could look something like this:


Interesting. I'd never seen anything like that in the pictures I've seen. I've heard of using the riser as a bass trap, but hadn't seen anything visually.


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## Owen Bartley (Oct 18, 2006)

I think that's a pretty common way to do it. You can use whatever works best in your setup, and get creative if you have to. I think the top / back is more difficult, especially if you have furniture legs to worry about.


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