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The Cinemar Home Theater Construction Thread - Page 6

post #151 of 2749
3/8/10 at 1:58pm
Quote:
Originally Posted by mcascio View Post


I feel like I have a shrinking room.

I know how you feel...my planned room is down to ~12'8" width and I think I am about to lose another 1"
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post #152 of 2749
3/8/10 at 2:41pm
mcascio,

What are the dimensions of your columns?
Builder was nice enough to put a support beam about 12" off my proposed wall. I am thinking with the 2x6 plate and double DD my coumns will have to protrude about 10" maybe a hair more?
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post #153 of 2749
3/8/10 at 3:20pm
Quote:
Originally Posted by mcascio View Post

Hi Ted,

Are you saying that if I don't space the double stud walls an inch apart, the sound proofing may not work?

Listen to Ted. An inch is the minimum.

Studies have shown that more space equals better results. I have 13" between the walls of my theater and mechanical room (overkill), then 1" between the bathroom and music room walls. It is important to point out that you should also ensure that the studs in the two walls don't line up with each other.
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post #154 of 2749
3/8/10 at 4:13pm
Thread Starter 
Quote:
Originally Posted by Larry M View Post

mcascio,

What are the dimensions of your columns?
Builder was nice enough to put a support beam about 12" off my proposed wall. I am thinking with the 2x6 plate and double DD my coumns will have to protrude about 10" maybe a hair more?

LarryM,

My proposed columns are 1'5" wide x 9" deep. In my case, I sized them to fit my speakers.
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post #155 of 2749
3/8/10 at 5:25pm
Thread Starter 
Quote:
Originally Posted by Audixium View Post

Listen to Ted. An inch is the minimum.

Studies have shown that more space equals better results. I have 13" between the walls of my theater and mechanical room (overkill), then 1" between the bathroom and music room walls. It is important to point out that you should also ensure that the studs in the two walls don't line up with each other.

With that said and space being a concern, what's better for sound proofing?
1) Double Stud Wall with 1/2" spacing
2) Staggered Stud Wall

I'm assuming number 1 is still preferred.
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post #156 of 2749
3/9/10 at 4:12am
Quote:
Originally Posted by mcascio View Post

LarryM,

My proposed columns are 1'5" wide x 9" deep. In my case, I sized them to fit my speakers.


Ok great that is pretty close to what I am thinking
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post #157 of 2749
3/9/10 at 5:08am
Quote:
Originally Posted by mcascio View Post

With that said and space being a concern, what's better for sound proofing?
1) Double Stud Wall with 1/2" spacing
2) Staggered Stud Wall

I'm assuming number 1 is still preferred.

Yes, double wall would still be preferred. I don't understand why you would construct a double wall and not go an extra 1/2" to make it a full 1" spacing...is there an obstruction to work around? What is it about that extra 1/2" that makes you not want the full 1"?

The way sound isolation works is you either go all the way or don't play at all. One thing like a warped stud coupling your framing can cancel out all your other efforts (and expenses). I personally do not want to go through all this isolation effort only to end up with one small thing (like a 1/2" decision) making everything moot.

I know how it feels losing floor space. But in the end I chose to do all I can on the isolation front. I suggest you reconsider that 1/2".
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post #158 of 2749
3/9/10 at 5:47am
Quote:
Originally Posted by Larry M View Post


1) Wood is preferred over steel studs correct? Only in a single stud application. Once decoupled, it doesn't matter. Most here are using decoupled framing.

2) Along the poured concrete foundation, should there be spacing between the 2x6 top and bottom plate and the concrete walls or can it be installed up against the wall? If yes how much is required? (I see you mentioned 1 inch above for what I believe to be back to back wood framing) Same 1" min spacing between the foundation and new framed wall. Also, you only need a 2x4 frame, not 2x6 or staggered.

3) In the staggered stud for a new wall scenario; am I putting studs every 8 or 16? i.e. the sheetrock touches a wood stud every 16 when a staggered stud is set every 8 or the sheetrock touches a wood stud every 32 when a staggered stud is set every 16? I've seen you mention 24 OC in other threads before, maybe I am not visualizing it correctly? 24" OC is when you're framing a single stud wall. Next so a foundation, the addition of a framed wall creates a double wall system. No need to stagger.

Currently I'm planning 2x6 plates with staggered 2x4s, double 5/8 drywall, and of course green glue.

Next to a foundation, use a single row of studs, wood or steel, 16" or 24" OC. Separate from foundation by 1". The other walls that separate the theater from the rest of the basement could be staggered, better to build double walls, however.
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post #159 of 2749
3/9/10 at 7:13am
Thread Starter 
Quote:
Originally Posted by Audixium View Post

Yes, double wall would still be preferred. I don't understand why you would construct a double wall and not go an extra 1/2" to make it a full 1" spacing...is there an obstruction to work around? What is it about that extra 1/2" that makes you not want the full 1"?

The way sound isolation works is you either go all the way or don't play at all. One thing like a warped stud coupling your framing can cancel out all your other efforts (and expenses). I personally do not want to go through all this isolation effort only to end up with one small thing (like a 1/2" decision) making everything moot.

I know how it feels losing floor space. But in the end I chose to do all I can on the isolation front. I suggest you reconsider that 1/2".

Thanks for all the great info. While a .5" may not sound like much, I'm currently spaced at a .25". So it's really .75" x 4 walls. So I'll lose another 3" in the room. It wouldn't be that big of a deal, but I already have a tight squeeze between the back row and a column. I think I'm down to about 19" between the column and the back row chair. Knowing how this distance affects soundproofing though allows me to re-evaluate the design again prior to construction.
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post #160 of 2749
3/9/10 at 8:33am
It's good to get used to re-evaluating in the design phase. Because during the build phase you will be forced to accept change due to issues that were unforeseen. That is why I asked about your tolerance for a 1/2" change. You might be in for bigger surprises than that once you are actually in the construction phase. I think most of the build threads over the past four to five years have proven that out.

Unfortunately compromises are part of every build. I would rather not potentially compromise the sound isolation over needing that last half inch of interior dimension.

I think you could use some of that awesome creativity to come up with a solution that accommodates both issues adequately. And again, listen to Ted .
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post #161 of 2749
3/9/10 at 1:40pm
Thread Starter 
Ted or Audixium,

If I go with an inch off the foundation for some of the walls, does it make sense for me to add a 1/2" of Rigid Foam insulation to increase the R-Value a bit? I'm assuming if the 2x4 wall warped a bit it wouldn't really make much of a difference if it's hitting the foam.

So it would be:
* Concrete Foundation
* 1/2" Rigid Foam
* 1/2" Air Gap
* 2x4 Framed Wall
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post #162 of 2749
3/9/10 at 1:42pm
I would not encourage the use of the foam. If the stud hits the foam toy are limiting the independent movement of the wall, which is a compromise.
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post #163 of 2749
3/9/10 at 1:46pm
Thread Starter 
Great. You just saved me a few bucks.
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post #164 of 2749
3/9/10 at 1:57pm
Quote:
Originally Posted by mcascio View Post

Thanks for all the great info. While a .5" may not sound like much, I'm currently spaced at a .25". So it's really .75" x 4 walls. So I'll lose another 3" in the room. It wouldn't be that big of a deal, but I already have a tight squeeze between the back row and a column. I think I'm down to about 19" between the column and the back row chair. Knowing how this distance affects soundproofing though allows me to re-evaluate the design again prior to construction.

Same here...I'd like the room to look as uniform as possible but currently I don't know how to do that with the structural beam placed where it is Would be nice to just space 3 columns where need be wouldn't it
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post #165 of 2749
3/10/10 at 7:33am
Thread Starter 
Larry,
Always seems like there's an obstacle around every corner doesn't it?

Ted,
Question on ductwork and soundproofing.
I have a total of six 6" ducts above the theater. Two of those six service the theater room. The basement will have it's own trunk line and be zoned separate from the rest of the house. My theory was to replace the six 6" ducts with insulated flexible ducts.

Do I need to install insulated flexible ducts in the entire basement or is that overkill and not worth the extra cost?

Or do I need to have the main duct servicing the basement lined with insulation as well?

Keep in mind, my main concern is soundproofing to the floor above. While I don't want the basement to be flooded with sound, I'm not as concerned about the adjoining bathroom, furnance room and bar area. The only planned bedroom in the lower level will be on the opposite end of the house as the theater.

One other note, the insulated flexible duct's will travel about 20' before it enters the main trunk duct.
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post #166 of 2749
3/10/10 at 8:03am
FWIW - I'm inserting Flex Duct sections in all 22 of my current supply runs since they are already exposed. I figure it is better to do it now instead of realize after everything is sealed up that I should have done it to begin with.

Perhaps Ted could chime in regarding how long of a Flex Duct section is the absolute minimum. I had planned somewhere around six feet for each run. But some runs I only have access to two feet.

If I were you I'd just go ahead and do it so you don't regret it later.
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post #167 of 2749
3/10/10 at 8:38am
Here's the scoop on ductwork. If it is above the decoupled, massive and damped ceiling and does not provide supply and return to the room in question, then you can leave it alone.

If, however, the duct is going to service the room, you have to take precautions. You cannot simply cut a hole in the decoupled, massive, damped ceiling drywall and think for a moment that ultra-lightweight flex duct is going to do a solitary thing, because it won't.

Picture the 6" diameter hole in the ceiling with flex duct going into the ceiling cavity. High energy sound waves will simply "see" the hole in the drywall and off it goes. The flex has virtually no mass, and consequently the soundwave will simply pass through the flex and enter the subfloor above as well as the joists. Also, cross-talk will contaminate the other ducts, pipes, etc above that ceiling.

You have to build mufflers (generally within the soffits) that treat the noise before it is allowed to leave that room.
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post #168 of 2749
3/14/10 at 3:25pm
Thread Starter 
Hi Ted,

Can you elaborate on sound proofing with the insulated duct? I thought the muffler solves the problem of sound passing through the insulated flex duct but what about the gaping 6" hole in the drywall?

I've attached a diagram in hopes that it will help you see the situation I'm in where the vents will enter the room.

The main trunk is outside the theater and on the otherside of an I-Beam. So going over the I-Beam and through the joists are really my only option.

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post #169 of 2749
3/14/10 at 3:46pm
With that large opening directly across from the room opening I would imagine that you would have a large sound leaking problem
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post #170 of 2749
3/14/10 at 9:02pm
Mario...

Before the writer's strike a couple of years ago put a hold on my home theater build, I had a similar idea for wainscoting my room much like yours, only in stained wood. At the time BPape had turned me on to Ethan Winer's article about using such paneling to hide a bass trap.

See this page in general: http://www.ethanwiner.com/basstrap.html and this drawing from that article in particular: http://www.ethanwiner.com/BTPlans.gif

Using the 1/4 plywood on the outside of each panel, as shown in the drawings, then applying molding around the edges of each one, would create the look I think you're after, and make the bottom half of your room a bass trap. Of course, once you hit ear level height, you'll still want to have some kind of acoustical treatment (above the chair rail.)

Hopefully, ]I'll be able to jump back into my own long-dormant build by this summer. But reading your thread reminded me of this article, and I thought I'd give you another option to get the paneling look you want.

Oh... and when the heck is DVDLobby 3.90 coming out? My MainLobby system feels incomplete.

Chip
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post #171 of 2749
3/15/10 at 9:14am
mcascio, your design is adequate, however if possible you should consider:
  • Doing double drywall + Green glue surrounding the soffit
  • and running the HVAC though the soffit with flex duct before it exits into the floor joist cavity

This causes the sound to be muffled in the flex duct inside the soffit before it exits the theater. Ted's diagram shows this, see my build thread link below for an example.
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post #172 of 2749
3/15/10 at 12:54pm
mcascio, the issue is that the flex needs to travel through the soffit for as long as possible before leaving the soffit. Your diagram shows a straight shot and no travel through the soffit. See how my image has the duct taking a 90 degree turn and travels thru the soffit?
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post #173 of 2749
3/15/10 at 2:04pm
Thread Starter 
Thanks Chip,

I'll take a peek at those links to see if they provide anymore insight. I hope you can start digging into yours this summer. At the pace I'm going, it may be summer before I start.

I just received another beta of DVDLobby 3.90 for testing. Our problem has been continual scope creep. More and more features are getting rolled in that weren't originally part of our plan. But in the end, it's gonna be awesome.

Thanks 3fingerbrown, I was hoping the double-drywall above would have been enough.

Ted,
So is the idea that if you have two 6" holes only 1' apart vertically you've created a large sound seep-hole...but if you stagger the 6" holes by running the insulated flex duct through the soffit, you've helped eliminate the problem? Sorry - I like to figure out the logic behind these remedies. If so, how far is far enough? 2', 3', etc? I'm guessing that by introducing these holes for the vents, I'll also need to now build backer boxes for the can lights that are also in the soffits?

Also, does the hole run need to be insulated flex duct or just the part running within the soffit?
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post #174 of 2749
3/15/10 at 2:11pm
You want at least 6' I would say. The duct length doesnt matter as much as the closeness of the holes together. as the bass goes right through the duct
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post #175 of 2749
3/20/10 at 8:45am
Thread Starter 
Progress has been slow to say the least. I had some sump pump issues which is actually a good thing and forcing me to take extra precautions before construction.

I've got two new sump pumps ordered and plan on having a completely separate pvc line run out for it just in case the first gets backed up. After considering a battery backup sump, I'm now leaning towards a Generac Guardian system. I think that will give me peace of mind. And by time I add up the battery backup system and a gas generator which would be the next backup solution, it starts to get up there in price anyways. I've done a lot of things to get my energy usage down over the past year so I think I can safely get away with an 8kw unit without a problem.

Thanks adammb,

If I'm not mistaken, you did the dead vents, didn't you? I'm wondering if I still need to implement those in my install?
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post #176 of 2749
3/21/10 at 7:05am
Thread Starter 
I'll probably need to build a subfloor in the lower part of the theater. It'll probably be raised about 5 1/2" up.

So my theory is to have them build it up using 2x6 treated lumber just in case there was ever a small amount of water to flood that lowest point.

Then fill it with R13 insulation leaving a few inches of air gap between the insulation and the floor. So if it did flood, it wouldn't get the insulation wet.

Does anyone know if this will create a major sound issue for the room?
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post #177 of 2749
3/21/10 at 9:40am
Thread Starter 
One more question. Is it necessary for me to have the entire main ductwork that services the basement level insulated for soundproofing? Or is it enough just to some near the theater area insulated?
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post #178 of 2749
3/21/10 at 9:53am
Quote:
Originally Posted by mcascio View Post

I'll probably need to build a subfloor in the lower part of the theater. It'll probably be raised about 5 1/2" up.

So my theory is to have them build it up using 2x6 treated lumber just in case there was ever a small amount of water to flood that lowest point.

Then fill it with R13 insulation leaving a few inches of air gap between the insulation and the floor. So if it did flood, it wouldn't get the insulation wet.

Does anyone know if this will create a major sound issue for the room?

Mario, firstly you must use PT lumber if it is in contact with concrete, similarly you don't want insulation in direct contact with the concrete floor. Perhaps you could layer a sheet of polythene to separate the insulation from the concrete... but I'm not sure.

Quote:
Originally Posted by mcascio View Post

One more question. Is it necessary for me to have the entire main ductwork that services the basement level insulated for soundproofing? Or is it enough just to some near the theater area insulated?

The rule of thumb that I've heard is that you want to muffle the last 15' - 20' and have three 90 degree bends with at least 5' sections. Effective muffling can be achieved by encasing in MDF or DD/GG.
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post #179 of 2749
3/22/10 at 7:41am
Quote:
Originally Posted by mcascio View Post

One more question. Is it necessary for me to have the entire main ductwork that services the basement level insulated for soundproofing? Or is it enough just to some near the theater area insulated?

Generally the ducts that are up in the joists are left alone. The ducts that service the room will need to have a treatment similar to what Moggie described.
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post #180 of 2749
3/22/10 at 8:03am
Thread Starter 
Ted,

In the question just above you quoted I was actually referring to the rigid ducts from the main trunk that service the entire basement. Does the same hold true?

Also, is the term "muffling" the same as a dead vent? Or are they two separate terms?

I think I can route the insulated flex ducts in on the far side of the room and then run it through a soffit and underneath the double drywall on the ceiling.

Also, any tips or tricks for handling cold air returns?
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