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First, some background on the HT project.


While taking a break from the construction the other night, I started to think about the hundreds or even thousands of posts I've read over the last year and a half and all the information, ideas, and expertise that people have openly shared in their posts. I then realized that I haven't shared anything of what I'm up to with the Forum. Fortunately, I have taken a couple of hundred pictures to this point, and its time to post some pics of the progress.


When initially deciding which techniques I would employ in building the room, I asked myself 2 questions.


1. What can I do to keep as much sound in the room as possible, and then deal with it acoustically later?

2. When sound gets past the drywall (and it will), what reasonable techniques can I apply to get in its way before it makes it to the rest of the house?


One question I know that I am going to get asked is "Why did you go through the expense of using Mass Loaded Vinyl and building a room within a room"?


Answer: When I originally started this back in 2002 it looked like Mass Loaded Vinyl, mounted to the studs, under the drywall, was a good solution. I ordered 800 sq' of MLV from a company in MA. While awaiting its arrival, I read a lot of posts about the room within a room design and decided that was a better solution (for me). When the vinyl arrived I stored it thinking I would sell it off some day. As I built the walls of the HT I realized that hanging limp in the 1" air gap between the walls was an ideal place for the mass loaded vinyl. Plus, it was no longer on a pallet in the middle of my garage floor...LOL, problem solved!



HT Specs:


Room Dimensions

- 12'w x 21'd x 7'h


Room Construction (to this point)


Double wall with floating ceiling (room within room)

- 2x4 walls assembled with screws for rigidity

- Internal walls are set at 1" from external walls and sit on a strip of mass loaded vinyl to give some disconnection from concrete floor

- Internal walls are bolted to concrete floor with 3" Tapcon concrete screws (somewhat negating the disconnection of the vinyl)

- 2x6 floating joists are doubled up to control twisting and give a 3" surface to install the ceiling MLV and drywall to

- Floating joists are bolted to the top plate of the internal walls for rigidity and to also help control twisting of the joists

- Internal Walls and Floating joists are set 1" below the existing joists for disconnection clearance


Room completely encased in Mass loaded vinyl

- MLV is installed very-very loosely on the inside face of the outside walls

- MLV comes over the top plate of the internal walls and under the floating joists and is joined to the MLV that is installed on the underside of the floating joists there-by sealing the entire room. (Not as bad as it sounds, see the pics)

- All seams of the MLV are taped with Nashua metal HVAC tape (Very sticky)

- MLV is sealed to the floor with silicone caulk (sticks really well to concrete)

- MLV on the 2 concrete walls comes down 24" to cover the basement windows, help negate flanking, and to maintain the airtight integrity of the room. Since the metal tape does not stick well to concrete, the concrete was treated with construction adhesive as a base for the tape to stick to (worked very well)


Roxul AFB insulation in walls

- Purchased this (1.5x cost of FG) before I read some threads questioning its ability to stop sound better than FG (had to stick it somewhere)...LOL


Owens Corning R13 in ceiling (multiple layers)

- Easier to stuff between the staggered joists than Roxul


Double 1/2" drywall (opposing directions) (glued and screwed)

- Have to hang 70 sheets of 1/2" drywall, couldn't bring myself to hang 35 of 1/2" and 35 of 5/8" X type


Double Safe and Sound doors (Owens Corning) with a 3" air lock

- Doors will open in opposing directions

- Doors will be jammed with 1" poplar (dense)

- Doors will be jammed individually within 1/4" of each other and then joined with acoustic caulk

- Doors will be completely sealed to jamb and threshold


Please feel free to comment, criticize or just ask (why did you do that...LOL)



Zoomer
 

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This pic is a view of the West wall in the HT. This is the 1st or external of the dual wall construction. I drew a couple of lines to show the stairway that is just on the other side of this wall. The wall is insulated with Roxul AFB and The opening is where the equipment rack will go.
 

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This is a view of the same wall with Mass Loaded Vinyl installed. The vinyl is installed as loose as possible.
 

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This is a pic of the doorway to the HT. The vinyl is installed up into the joist cavities to keep sound from getting to the cold air return that is directly behind the vinyl.
 

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This is a pic of the vinyl going up on the North wall. On the left side you can see that the internal wall has been built at the doorway. Hanging the vinyl is an interesting task, I had to keep telling myself.... keep it loose. My best description of what its like to work with this stuff is like being in a tent when it collapses, except a tent doesn't weigh 1lb per sq ft.
 

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In this pic, the wall on the left will be installed to the right, when the vinyl is finished.
 

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Zoomer - Sounds like you've done your research. I have 2 questions on the MLV - where did you buy it (manufacturer & product name) and why did you install it "limp"?


BTW - using the MLV AND the room within a room concept certainly can't be a bad idea based on some recent posts here.
 

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schmidtwi,


I purchased mine from a company I found on the Internet. I won't mention their name because their website sayes "commercial sales only". I called them and told them what I needed, and they shipped it to me. If you search the Internet you'll find a lot of places that sell 1lb/sq' Mass Loaded Vinyl. 16 months ago when I purchased it, I paid about $1.25 a sq'. One thing to keep in mind is this stuff is HEAVY. Shipping charges can add up.


Mass Loaded Vinyl is also referred to as Limp Mass Vinyl. From all the information I have read, this stuff is best applied as limp/loose as possible. Thats why I installed it on the inside face of the outside wall rather than behind the drywall.


Zoomer
 

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This pic shows the MLV sealed to the floor with silicone caulk. I used this instead of acoustic caulk for 2 reasons. The GE SiliconeII caulk sticks really well to concrete and I hadn't made it to the builders supply to pickup acoustic caulk yet....LOL. By the way, the silicone caulk is $5.00 for a small tube and the acoustic caluk is $3.25 for a Quart tube. I finally made it to the builders supply and picked up a case of acoustic caulk.
 

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Here is a view of a piece of MLV that is attached to the outside wall and ready for the internal wall to be put in place.
 

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A picture of the internal wall with a strip of MLV installed to help disconnect it from the concrete.
 

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Here is a pic of the wall in place with the MLV draped over the top plate and the floating joists installed.
 

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In this pic, you see the 2 poured concrete walls with MLV affixed to them and draped over the top plates of the walls. This serves 3 purposes, it covers the glass block windows, helps with sound flanking off the concrete and up into the house, and helps with the airtight seal of the room.
 

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A pic of the floating joists being installed. The insulation goes in and then the joist is bolted into place.
 

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Here is a close up of the joists bolted in place and the MLV draped over the top plate of the internal wall. When the MLV is applied to the ceiling it will be sealed to the pieces that drape over the walls and create an airtight envelope in the room. One thing to remember is that I will have 2 inbound and 2 return air ducts suppling and removing air from the room. At that point I can (attempt to) control the sound leaving the room through the air ducts with bends or baffles.
 

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Thanks Zoomer, I'll have to search online for some decent pricing. The best pricing I've seen so far is $385 for a 4.5' x 60' roll.


Why did you decide to use nails (or screws) to attach the vinyl to the studs? Wouldn't there be less sound transfer to the studs if you used a silicone-based adhesive?
 

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Wow - airtight is certainly the right word for this room. Be careful that you don't end up suffocating in there...


I should think a bomb could go off in that room, and nobody in the rest of the house will be aware of it!


Dwight
 
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