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Simpson Dedicated Theater Build

post #1 of 11
Thread Starter 

I'm starting this thread to see if the location I have available to me would suffice and be worth the effort to turn into a HT. It's a basement bedroom location (13'-6" x 15'-6") at the outside corner of my home with two exterior walls and three windows (less that 7sq.ft each). Ceiling height is 8'-6" from concrete floor to bottom of joist. It is a full walkout on both sides of the room. The room site directly below the master bedroom and shares a cold air return with it.

- Use as a dedicated HTR with 106" screen and 4 theater seats
- Prevent as much sound from escaping the room so as not to disturb others.
- Make it as acoustically correct as I can afford :-)

- BenQ w1070 PJ
- Pioneer Elite 7.1 AVR
- 106" diag fixed screen with frame
- Klipsch Synergy speakers F/C/S
- Velodyne 12" Active/Passive 150W Sub
- Sony BR player
- Dish HD

I attached an illustration. I plan on using:

Ceiling (exposed joist currently):
Double R13 batts in the joists with whisper clips, hat channel 5/8" DD/GG.
Considering a soffit with some lights, will build sound boxes above them if so.
Have 1 - 6" metal heat run and 1 - 4" fresh return air vent pipe in ceiling to contend with, plan on wrapping them with insulation? Do I need more for these?

Currently have 1/2 "DW, replace everything with 5/8" DD/GG. Use sound isolation caulk on all wall/floor seams/ and electrical boxes. Maybe use 5/8" OSB/Dwall and GG? This way I have attachment substrate.

Carpet over concrete, no soundproofing

Replace with solid core and door sealing products.

Sound dampening panels in the room depending on sound reflections.
Base traps (not sure where yet, probably front wall.


1. Wall framing - The existing walls (2 interior and 2 exterior) are not decoupled from the ceiling joists above as they are all load baring walls. Will 5/8" DD/GG be effective in stopping sounds from traveling up the wall cavity to the room above if they are coupled? Can't really afford to loose another 6" from the room. Would I short circuit if I trimmed out the windows to the wall?

2. Windows - they are double pane insulated but the exterior walls have 1.5" extruded foam to which they are nailed to (maybe this decouples them?). Will these be an issue to transferring sound through the wall cavity to the room above? The home has cement board siding which really dampens outside noise. I plan on using some sort of blackout window treatment for light and maybe to prevent high frequency reflection, thoughts?

3. Cold air return - not sure what can be done with that since I need a return vent in the room. I don't care about hearing the air flow too much, just not to use it as an amplifier to the room above and be the weak link. Maybe a baffle in the wall to help dampen.

Any advice on the approach and if this room is worth the investment? I'm not looking for the ultimate HT, just a place that I can be proud to invest in and enjoy the results.

Thanks in advance!
post #2 of 11
Thread Starter 
I was considering a larger screen yes, and bringing my seating a few feet closer off the back wall.

I would like to avoid any "Swiss cheese" because this is directly below the master bedroom. Most of the time we will both be watching but for obvious reasons it needs to be the best I can "afford".

Biggest concern is doing DD/GG with out decoupling on the walls and if it will be effective enough. Or would it be a waste with out decoupling? I do plan on decoupling the ceiling though. GG is expensive and I wouldn't want to throw away money on a solution that would not be effective.

If there is a way to decouple (whisper clips) the walls w/o loosing 2-3 inches on each one I'd be interested in learning how. I would loose 6 inches in room width/depth. No a huge amount but if it will make that big of a difference in sound isolation over just using DD/GG alone I may consider it.
Edited by simpsonb4 - 1/9/14 at 6:35am
post #3 of 11
Thread Starter 
Originally Posted by DavidK442 View Post

up-sized again to 9.5' wide because scope movies just didn't have the impact I wanted. smile.gif)

Is that a 9'-5" diag or width?
post #4 of 11
No decoupling = no bass containment.

If you just did DD and GG, you would likely not hear much outside the theater in the mid or high frequencies but the bass is gonna resonate throughout the framing in the house. Decoupling doesn't add the much more to the build cost, IMO. Source the clips where you can and buy the hat track at a local commercial drywall supply house. Also think about Big's suggestion for the first layer being OSB instead of drywall. I wish I would have done that so I didn't have to keep measuring where the darn hat track was to screw anything down.

Also, don't forget to alter, reduce or eliminate any flanking path for sound. (HVAC duct work, can light holes (build can light boxes) and fully sealed electrical outlets and a massively heavy and gasketed entry door.

brain melt yet????
post #5 of 11
Thread Starter 
Thanks for the response! Yes, it's starting to melt!! The more I think about it the more I think I should do clips and track on the walls as you and others suggest. I'm not able to decouple to actual wall so clips and hat channel with OSB/Drywall/GG is my best option. I think that will do a lot.

Now I do have 3 small windows in the room which I will be keeping in there. They are obviously nailed to the wall and I have no way of isolating them so would that be a major "leak point" and negate everything I'm trying to do?? The exterior wall build consists of 1" XPS foam, building paper and then Cement board siding. The windows are nailed through the foam into the wall studs. I do plan window treatments for light block and sound treatment at the least though.

About the floor, it's concrete, do I really need anything there? Or will carpet/pad be sufficient? There is no moisture barrier under the floor now but it is VERY dry, I have good drainage under the house. Never had any issues with moisture.

Hey, for the windows maybe I'll make some "interior shutters" out of 2 layers of 3/4" MDF and GG that I cover with fabric and just close them when needed...Light/Sound issues solved in one product!
Edited by simpsonb4 - 1/10/14 at 1:20pm
post #6 of 11
Can you flip the plan around, so that you are entering the theater at the seating area, instead of the screen area? If you needed to, you could have a step outside the door so that you enter at the riser height.... just a thought...

In terms of using two layers of drywall and the question of decoupling, those are two different subjects. The double drywall is about mass, the more mass the harder for the wall to vibrate. The decoupling is about, well decoupling, adding that is to reduce the ability of the sound vibrations to move from one structure to another.

It isn't one or the other, they work together, as part of the overall sound isolation design. If you can only afford to do one, for whatever reason, then go ahead and do it, that is better than not doing either.

For your windows, you can create window plugs that are heavy (think mass here) and fit tightly into the framing of your wall. If needed, for fire code, these can be removed.
post #7 of 11
Thread Starter 
Yes, I will use the systems together. The extra cost to clip the walls is not the issue it's talking up room width. I understand that decoupling will be a major contributor so thank you for the confirmation:)

I can't flip the layout, I'm locked with a bathroom there frown.gif

As for the windows I like the idea of making hinged plugs like shutters that fit inside the window jambs and will be sealed with stripping of some sort when closed. I can then open them when I want and they still look good, anyone ever do this?

So the windows (even plugged) won't be a weak point? I imagine a little but not enough to warrant not doing the rest of the soundproofing. Don't want to put all that effort and money into it if these will negate it.

Any suggestions on the floor? I'll will be using acoustical sealant on all joints including the floor/wall joints. Was concerned more about adding height for a step up is all. I could add a quiet matt and osb if I need to I guess.
post #8 of 11
You can flip the room, I'm suggesting the door, as you have it now, enters onto the riser area instead of the screen area . It is a preference, I enjoy walking into the rear of the theater, and stepping down into it, versus walking in by the screen. It isn't really a performance issue, just a design choice.

Window hinged shutters would likely cause vibrations/sounds and not be as tight as a plug (though would need to see the actual design to know for sure. With window plugs, they are generally effective if nice and dense and fit tightly.

For the floor, you could add one layer of subfloor, if desired, which won't eat up lots of your height. The other advantage of adding the subfloor is that it keeps the floor warmer than carpet on concrete.
post #9 of 11
Thread Starter 
I see, flip the screen wall. If I did it would cover the window and I would loose the ability to build a build any type of screen wall enclosure. It's a thought though. Really don't like the idea of permanently covering up a window, would probably take it out instead for better looks on the exterior.

So will window plugs properly fitted it won't negate doing everything else?

Is the floor really necessary and would I be foolish to leave it with just carpet?

Main issues here is that I don't want the room to be like "you almost could have had a soundproof room if you did this..."eek.gif

Thanks, I really appreciate your expertise!
Edited by simpsonb4 - 1/10/14 at 3:49pm
post #10 of 11
Nice and tight window plugs will not negate the rest of your sound isolation work. If you are shooting for the best sound isolation you can have, then you do need to address the floor, but most guys don't do lots to the floor, due to the height issue. Since you have 8.5' to work with, and you are going for excellent isolation, I would consider treating the floor. We're not talking about the loss of tons of height, nor a significant amount cost.
post #11 of 11
Thread Starter 
Since you put it like that it makes sense. So just a sound mat and 5/8 OSB glued? I search for them in here. I wouldn't need it under the riser because that will be built up with multiple layers and insulated anyway.

Thanks for pointing me in the right direction:)smile.gif
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