Triple Layer Drywall (or More) - Post your Results, Please - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 14 Old 11-02-2018, 01:21 PM - Thread Starter
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Triple Layer Drywall (or More) - Post your Results, Please

I'm interested to know who has done 3 or more layers of dywall and/or OSB. @BIGmouthinDC has mentioned he has done 2 such theaters. Anyone else? I like my bass but I'm not going crazy by DIY Speakers standards; probably just 4 21" LLTs in 15ft^3 each.

1. Do you think you obtained better bass isolation vs 2 layers?

2. Was it worth the extra labor and expense?

3. Did it add any additional complexity over 2 layers, other than a few more clips and channel to support the weight?

4. Do you really need Green Glue between every layer, or will most of the damping benefit come from the outer (inner?) two layers?

5. Did you do all the walls and ceiling with 3 or more layers?

6. Did you use clips and channel for all the surfaces?

7. What did you do to isolate the floor?

8. Where is your theater located relative to the rest of the house?

9. What else do I need to know that I haven't considered (besides doors are the weak link)?

Thanks in advance,

Mike
Future proprietor of the Gearhead Garage Theater
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post #2 of 14 Old 11-02-2018, 01:29 PM
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Beast Unleashed and Curve Frenzy are the two I did, both basement builds. Question #9 don't overlook isolating the floor, and addressing any shared duct work. Conduits to an equipment room for wiring can also conduct sound. After the wires are in stuff the ends with insulation.
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post #3 of 14 Old 11-02-2018, 02:38 PM - Thread Starter
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Thanks, BIG.

I plan to use U-boats as a minimum and probably the Kinetics RIM system if it doesn't break the bank. HVAC will be a separate system from the house without any shared ductwork, not even makeup air. The equipment room will be adjacent to the triple layer theater enclosure, but still inside of the exterior theater shell over the garage.

I'll go review those build threads now.

Thanks!
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post #4 of 14 Old 12-05-2018, 11:08 AM
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I realize this is a month old, and I am currently in the middle of building my theater with 3 layers of gyp bd, so I can't comment on results yet, but I did want to share what I've gathered so far:

Quote:
Originally Posted by mhutchins View Post
1. Do you think you obtained better bass isolation vs 2 layers?
1. Can't tell yet, but my brother's theater uses 2 layers and GG and his subwoofers are insanely loud and flat to 5hz. I will have a similar setup so I'll have a nice point of reference to compare when I'm done.

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Originally Posted by mhutchins View Post
2. Was it worth the extra labor and expense?
2. Can't tell yet.

Quote:
Originally Posted by mhutchins View Post
3. Did it add any additional complexity over 2 layers, other than a few more clips and channel to support the weight?
3. In some ways yes, but actually it makes things easier in a sense too. For instance I don't have to worry about large gaps too much as long as I stagger my seams the right way, I'll always have at least 2 layers of solid gyp bd in all locations. Also made caulking all layers easier. Was even able to provide solid wood substrate for mounting speakers and lights into. If interested in my design (extremely fast, easy and cheap), let me know.

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4. Do you really need Green Glue between every layer, or will most of the damping benefit come from the outer (inner?) two layers?
4. Not worried about using GG. Maybe with 2 layers, but with 3 layers doesn't seem worth the hassle. Not even sure if it makes any difference with 3 layers.

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Originally Posted by mhutchins View Post
5. Did you do all the walls and ceiling with 3 or more layers?
5. Yes, all walls and ceiling.

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Originally Posted by mhutchins View Post
6. Did you use clips and channel for all the surfaces?
6. Only used clips on the ceiling and one wall where I couldn't "decouple" the framing.

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Originally Posted by mhutchins View Post
7. What did you do to isolate the floor?
7. It's in the basement, so wasn't too worried about the floor. However, I still set my wall framing on rubber pads to provide a little more vibration absorption. There was a bit more to it than that, if interested in full construction details let me know.

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Originally Posted by mhutchins View Post
8. Where is your theater located relative to the rest of the house?
8. Basement on conc slab.

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Originally Posted by mhutchins View Post
9. What else do I need to know that I haven't considered (besides doors are the weak link)?
9. See below:

a. Take tons of photos during the process for reference later.
b. I've been marking exact locations for all my wire penetrations (for example I write on adjacent studs 'wire is 46.5 in above floor and 54 in from framing')
c. I've been marking exact locations of my hat channel center lines, and transferring them to adjacent surfaces as each layer goes up.
d. You don't need to space your hat channels on 16" centers instead of 24" for 3 layers, as long as you have the correct number of clips. For me, using 16" centers would've given me way too many clips - each clip would only be holding 14-16 lbs. Going to 24" centers put me closer (still 5 lbs under) to the 36 lbs per clip sweet spot. I verified this with the clip manufacturer.
e. Do NOT forget you will need a safe spot to store several thousand pounds of drywall. To do my 250 sq ft theater I needed a stack 5ft high that weighed over 3 TONS.
f. Framing the door jamb on hinge side needs to be heavy duty, like a 2x8 or 2x6 if it swings into the theater side of the wall. Let me know if you want to see pics of what I did.
g. RSIC DC04 clips every 4 ft are cheaper than RSIC-1's everywhere.
h. Use 1" fine thread #6 or #8 drywall screws for the first layer on hat channels
i. Use 1-5/8" fine thread #6 or #8 drywall screws for the second layer on hat channels
j. Use 2-3/8" fine thread #8 drywall screws for the third layer on hat channels
k. 25-30 screws per sheet for walls, 30-36 screws per sheet for the ceiling
l. I only needed about 8 or 9 putty pads, but I bought a 20 pack of putty pads off Amazon so I could double-up around my electrical boxes, and have enough left over to fill in any large gaps between drywall sheets or other penetrations. That's worked pretty nice.
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post #5 of 14 Old 12-05-2018, 06:58 PM - Thread Starter
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^^^^^^^^^^^

Thanks Ethan, I really appreciate the reply!

I hope you can find the time to start a build thread to share some of what you learned from your brother's build and now your own build, as well. I would love to see the renders for your build if you have any. The renders you posted in your brother's build were fantastic, so I'm guessing the renders for your theater must look pretty good too.

3. Did it add any additional complexity over 2 layers, other than a few more clips and channel to support the weight?
Quote:
3. In some ways yes, but actually it makes things easier in a sense too. For instance I don't have to worry about large gaps too much as long as I stagger my seams the right way, I'll always have at least 2 layers of solid gyp bd in all locations. Also made caulking all layers easier. Was even able to provide solid wood substrate for mounting speakers and lights into. If interested in my design (extremely fast, easy and cheap), let me know.
Yes please, I'm always interested in clever solutions that make things easier and/or better! Thanks for all the tips on #9 , too.

Thanks again,
Mike
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post #6 of 14 Old 12-07-2018, 09:33 AM
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If green glue is in the budget it will only help.

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JVC-RS540, 124" Wide 2.40:1 DIY Screen, Denon 8500H, Denon 6200W, Panasonic UB820 UHD Player, (3) iNuke 6000DSP; (2) iNuke NX3000D; (3) HTM-12; (14) RSL C34e surrounds; (2) 18" DA RSS460HO-4 Subwoofers; (1) DA UM18-22 18" Ultimax Subwoofer; (4) DA RSS390HO-4 15" Reference HO Subwoofers; BOSS Platform - (12) 12" Subwoofers
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post #7 of 14 Old 12-10-2018, 08:09 AM
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Quote:
Originally Posted by mhutchins View Post
Yes please, I'm always interested in clever solutions that make things easier and/or better! Thanks for all the tips on #9 , too.

Thanks again,
Mike

Man how did you remember I did my brother's theater? I actually forgot that I posted that lol. Sadly no renders for me, I already knew in my head what it would look like . But I still did 3D model a bunch in sketchup to help me visualize how to build it and to make sure my screen would fit, projector location would work, etc., like I modeled the studs and everything. Then I popped on my Vive and stood in my theater in VR to make sure everything "felt" right.


But on to my second layer trick...


I know some guys have used plywood or something like that for their first layer so that they have something to screw into, but the whole point of going 3 layers is to cheaply get as much mass as possible, so I didn't want to sacrifice any of it. Also didn't want to spend more $$ either. On my walls where the framing itself is attached via RSIC DC04's, that's no issue I just put up some blocking where I knew I'd be mounting speakers. But for the ceiling and the one wall where the gyp bd is mounting on clips and hat channels, blocking won't work. So how do I install speakers without relying on flimsy gyp bd anchors?

What I did was put up my first layer of gyp bd and located all my wire penetrations exactly where they needed to be, drilling holes just big enough for the wires to pass through. In my ceiling, I'm mounting 4 atmos speakers and I'll be installing 3 light fixtures (no electrical box, just straight wire coming through like speaker wire). So that's 7 wire penetrations in my ceiling.

For the second layer, I switched it up. Using the mounting template that came with my OWM5's, I figured I'd need 10 inches of 5/8" thick 3" MDF trim board. So I cut (4) 10" pieces, traced it on the gyp bd very close to where it would need to be for the speaker mount, then cut out the gyp bd and installed it with a 10" x 3" rectangle missing. Before putting up the gyp bd, I tested each cut with my template piece to make sure a tight fit. I then did the same for my electrical wires, but only did a 6" long piece centered directly on the wire. After I put the entire second layer up, I took my pieces of MDF trim, measured each cut out to locate the exact spot I needed to drill for my wire hole, then drilled my holes. The trim on the finished side has rounded edges, so I put the pieces in rounded edge first as it makes for a much easier install. After a quick test fit to make sure I drilled the hole in the right spot, I then caulk around the base of the wire penetration and the edges of the opening, and put in my MDF trim to infill the opening.

Because I have OCD I sanded them down a bit to get a perfectly even surface (They only stuck out by 1/32" but that bugged me). Now I have an MDF substrate to screw into for my speaker mount screws and whatever light fixtures I purchase. The third layer will cover the MDF trim infill pieces, and when I mount my speakers and lights, as long as my screws hit the MDF (which, of course, they will since I measured everything) it will be VERY difficult for anything to pull my speakers or lights out of the ceiling.


Attached photos for visual explanation.
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post #8 of 14 Old 12-10-2019, 03:49 PM - Thread Starter
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@below90hz

How is your theater build coming along?

Mike
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post #9 of 14 Old 12-10-2019, 08:12 PM
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Quote:
Originally Posted by mhutchins View Post
@below90hz

How is your theater build coming along?

Mike

Well it's almost done. I just need to finish putting up the door stops and gasketing, paint the doors and door frames, build some new subwoofers. I've been using it for the past couple months though and I have to say I am very pleased with how it turned out. The only thing I'm not 100% sure about is the level of sound attenuation. There is already a huge reduction in sound transmission, but since the doors aren't actually sealed (and I have 4 of them) I have yet to discover the full extent of the attenuation.


What did you decide to do with yours?



-Ethan

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post #10 of 14 Old 12-11-2019, 08:03 AM - Thread Starter
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Quote:
Originally Posted by below90hz View Post
Well it's almost done.
.
.
What did you decide to do with yours?

-Ethan
Hi Ethan,

That's great that you are on the home stretch toward completion!!

I finally got the green light on the theater and I have an architect working on the plans for an addition above our garage. I have been working with Nyal Mellor on some preliminary sound isolation issues to make sure they are addressed in the outer shell construction. I have decided to go with the Kinetics RIM system supporting a 3" Gypcrete floor for a full floating room-in-room design. Expensive, I know, but necessary to meet very stringent WAF criteria. I will start a build thread as soon as I have drawings I can post.

Mike
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post #11 of 14 Old 12-11-2019, 08:29 AM
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Quote:
Originally Posted by mhutchins View Post
necessary to meet very stringent WAF criteria.

Oh i know all about that. I was blessed with a wife who hates bass. The very tiniest, most minute, subtle vibration that only elephants and bats can detect will send her right down into the theater demanding I turn down the "ridiculously loud" volume. Like, it has to be at zero. Anything above "zero bass" and she acts like I kick puppies for a living.



I wish I could've done room within a room but my tiny townhouse just doesn't have the space. Neither does my tiny wallet come to think of it.

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post #12 of 14 Old 12-11-2019, 09:17 AM - Thread Starter
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I think our wives have a common genetic heritage. I feel your pain.


Fortunately I can create the space. On the other hand, I can't create unlimited funds. I'm sure this build will be limited by both time and money. I am struggling to stay focused on the room and not shop for gear. I keep reminding myself that any electronics I buy now will be obsolete by the time the theater is ready for gear. The only thing I purchased in advance were 8 of the DIYSG Concentric 8 coaxial speakers when they were discontinued. I plan to use 6 of these for my Atmos layer.

Mike
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post #13 of 14 Old 02-24-2020, 09:31 AM
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Quote:
Originally Posted by below90hz View Post
Man how did you remember I did my brother's theater? I actually forgot that I posted that lol. Sadly no renders for me, I already knew in my head what it would look like . But I still did 3D model a bunch in sketchup to help me visualize how to build it and to make sure my screen would fit, projector location would work, etc., like I modeled the studs and everything. Then I popped on my Vive and stood in my theater in VR to make sure everything "felt" right.


But on to my second layer trick...


I know some guys have used plywood or something like that for their first layer so that they have something to screw into, but the whole point of going 3 layers is to cheaply get as much mass as possible, so I didn't want to sacrifice any of it. Also didn't want to spend more $$ either. On my walls where the framing itself is attached via RSIC DC04's, that's no issue I just put up some blocking where I knew I'd be mounting speakers. But for the ceiling and the one wall where the gyp bd is mounting on clips and hat channels, blocking won't work. So how do I install speakers without relying on flimsy gyp bd anchors?

What I did was put up my first layer of gyp bd and located all my wire penetrations exactly where they needed to be, drilling holes just big enough for the wires to pass through. In my ceiling, I'm mounting 4 atmos speakers and I'll be installing 3 light fixtures (no electrical box, just straight wire coming through like speaker wire). So that's 7 wire penetrations in my ceiling.

For the second layer, I switched it up. Using the mounting template that came with my OWM5's, I figured I'd need 10 inches of 5/8" thick 3" MDF trim board. So I cut (4) 10" pieces, traced it on the gyp bd very close to where it would need to be for the speaker mount, then cut out the gyp bd and installed it with a 10" x 3" rectangle missing. Before putting up the gyp bd, I tested each cut with my template piece to make sure a tight fit. I then did the same for my electrical wires, but only did a 6" long piece centered directly on the wire. After I put the entire second layer up, I took my pieces of MDF trim, measured each cut out to locate the exact spot I needed to drill for my wire hole, then drilled my holes. The trim on the finished side has rounded edges, so I put the pieces in rounded edge first as it makes for a much easier install. After a quick test fit to make sure I drilled the hole in the right spot, I then caulk around the base of the wire penetration and the edges of the opening, and put in my MDF trim to infill the opening.

Because I have OCD I sanded them down a bit to get a perfectly even surface (They only stuck out by 1/32" but that bugged me). Now I have an MDF substrate to screw into for my speaker mount screws and whatever light fixtures I purchase. The third layer will cover the MDF trim infill pieces, and when I mount my speakers and lights, as long as my screws hit the MDF (which, of course, they will since I measured everything) it will be VERY difficult for anything to pull my speakers or lights out of the ceiling.


Attached photos for visual explanation.
Thank you so much for this. I am going to do the exact same thing. What is your plan for lights? Are you going to go with a surface mounted box with the light attached to that? Or a surface mounted light, attached to your backer box with bear wire under the light?
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post #14 of 14 Old 02-24-2020, 06:01 PM
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Quote:
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Thank you so much for this. I am going to do the exact same thing. What is your plan for lights? Are you going to go with a surface mounted box with the light attached to that? Or a surface mounted light, attached to your backer box with bear wire under the light?

I installed these lights from IKEA


They are an absolute insane value for the money and work perfectly. The only drawback is if you plan to use LED bulbs, you will probably hear a buzz. I tried like 6 different kinds of bulbs before i just settled on the ones that actually dimmed and weren't too loud. Obviously when you're actually watching something it doesn't matter since the lights are off anyways.
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