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Need help with wall/floor insulation in "unique" HT construction. (1 Viewer)

Rancho5

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Newb here. I've found countless usefull threads on how to build my HT, especially the "What would you do differently" thread. I, however, find myself in a unique position.

The attic space above the garage (entrance is in the home) will be our HT. We had it framed for a live load when we built the house. Currently it is 7'3" tall (7 when finished), 23' long and 10'3" wide (10 when finished). Cozy but doable I believe.

Since it is above the garage, and nothing is up there now, I am in the unique position of using anything I want for walls against the studs, and for flooring. I first just thought I'd sheetrock the walls and double the floors with 3/4 tongue and groove OSB. Then I started reading about bass traps, etc, and really got thinking about room acoustics. I figured I will build framed fiberglass traps and install them along the walls. I will run 3 inch tubing to all speaker locations for future growth but also will have access to the wiring by means of crawl spaces that run the length of the HT.

We plan on a projector and I currently have a Cambridge Soundworks system which I love. I will probably want to upgrade in the years to come however.

I have thought about a "room within a room" but it's only 10' wide to begin with.

So the question is: Do I automatically use sheetrock for the walls and ceiling and just use bass traps on the walls, etc, OR do I have other options? I have a limited budget so cost is a concern as well. I'm a DYI kind of guy.

Any help on these issues would be greatly appreciated.
 

brandonchenry

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well dont run 3" pipe to your speaker locations! What do you invision in the future? The current trend is heading towards wireless (you would still need to plug your speaker into power). 12g speaker wire should do you fine.

the only place I could fathom needing a 3" pipe would be from your rack to your projector.
 

Rancho5

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After reading many posts, it seems that most people are running wide pipe to each speaker location for future expansion. Or, at the very least, 2 sets of wire. Perhaps I have mis-read.

Any suggestions on the insulation, walls and ceiling?
 

Robert_J

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Double drywall, green glue and RISC clips for sound isolation. Bass traps, absorption panels, etc are for acoustics. They are very different things. What are your goals for this?

-Robert
 

Rancho5

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Goals: To have a great sounding HT built correctly. I have absolutely no walls to begin with, unlike some others on the forum, so there really are no limitations. I have noticed that many here have basement walls or game room walls to contend with or adapt to. I simply have a framed wooden box with space above, below and surrounding. I'd just hate to simply build this room and then discover, too late, that I should have used "such and such" for the walls, or the ceilings or floors.

If you could explain the relationship between insulation and acoustics I'd appreciate it. Without beinig an expert, it would seem that the goal would be to insulate as well as possible to create a "separate" environment from the rest of the home. If this is true, I'm just curious how to go about it.

Also if you could please explain bass traps, etc, as well. From what I gather they are used to correct imperfections in the acoustics of a room, but then again, I'm pretty new at this.

Thank you for your help.
 

Robert_J

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Sound isolation is when you try to contain all of the sound of the theater room inside its walls. It is easy until you try to contain the bass. To do that you need to add mass to the walls by using double drywall or a product called QuietRock. Between the 2 layers you add green glue. It absorbs some sound that is transfered between the two layers. You then add RISC clips between the inner drywall and the studs of the wall. Again, another layer to absorb more sound. It would even be better if you did the same on the other side of the wall. You have to have a solid core door and an air tight door sill. Seal up every electrical outlet. Use special air duct material to feed your HVAC to the room. After seeing the cost of this I determined that if someone else in the house is sleeping I would use the volume control to keep the sound outside the room to a comfortable level. When my wife and I watch movies the volume is cranked to the point you can feel the waves of bass though the concrete foundation.

In a room there will be peaks and valleys in the bass response. It is just the way the sound waves interact with the room boundaries. You can add large rolls of insulation (2 foot to 3 foot diameter and 8 feet tall) or you can add a parametric EQ to flatten out the bass response. It takes up much less space.

Sound absorption panels stop reflections. Take a look in the Projects section at RobertR's theater. The thread should be near the top. On one pic you can see the panels that are secured to the walls. You can cover your entire wall with them of stategically place them where you have the worst reflections.

-Robert
 

Rancho5

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Robert,

Thanks for your reply. I will begin searching "green glue" and "RISC" clips and their application.

The guy I'm hiring to frame in the catwalk to the HT suggested using 3/4 tounge and groove OSB for the base flooring. Two layers actually, opposing. I would be intereseted in your thoughts on this as well.
 

Robert_J

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Also look up Resiliant Channel products.

OSB will help but you have to compare the weight. Square foot to square foot, which is heavier? The heavier material will have a higher STC value.

-Robert
 

Rancho5

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I looked up the RSIC clips and green glue. For my budget it looks like green glue and doublel drywall will be what I do. I wish I could afford both.

Re: Flooring. The double layer of tongue-groove 3/4" OSB would be quite heavy. Not knowing what STC value is, could you please explain? I would be using green glue between the sheets.

Alec.
 

Robert_J

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STC

I'm not sure what the STC of OSB would be but I'm sure it is pretty high being that it is a very dense material. MDF or HDF would be better at soundproofing but it is much heavier (extra support may be needed) and it contains toxic chemicals. A little bit used for speaker boxes is OK. But covering the floor in the stuff may make you sick. I saw one place mentioning green glue between layers on the floor.

And if you go with a massive sub you will NOT be able to contain the bass. I think the slab of my house is as dense as it gets but at full blast I can feel it all the way on the other side of the house. It just a slight rumble at your feet and lights shaking just a little. Like a small earthquake.

-Robert
 

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