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Swamp build - Page 4

post #91 of 109
Flex is a good thing. Flex is a bad thing. It depends on the amount of flex, where the flex occurs and the purpose of the flex (application dependent).

For example, flex in structural walls can be a bad thing...unless the flex was engineered in to protect the structure from impact (think earthquake, high wind loads).

In sound isolation applications, flex will convert acoustic (kinetic) energy into heat...but not all of the acoustic energy. A certain amount of flex is required in constrained layer damping (think green glue between two sheets of dryall). In a clips + channel application, the objective is to allow some degree of flex in the channel, drywall, green glue components. There is a second purpose to this type of construction ... to reduce the amount of flex (or vibration) transferred into the underlying structure (framing). Once you have flex in the framing, you have a few things happening that you'd prefer not occur. One is that flex/vibration is now carried through to the structure allowing sound transmission to occur throughout the structure. A second is if the whole wall is flexing you are then turning the opposite side of the wall into a speaker...somewhat contrary to the original purpose (it's not a perfect world, some of that flex/vibration is going to make it through in any case ... it's the amount that gets through which is key). A secondary issue with 'too much flex' in the wall is simply when the wall deforms under stress, it snaps back into its static state. When it returns, it doesn't necessarily return at the same rate at which the deformation occured. Depending upon the material, this could be a faster or slower rate. Thus the wall is returning a portion of the energy back into the room out of phase and at a differerent frequency. Is this a problem? Answer: "depends". "Depends" meaning just how much energy is returned.

Saying flex is good, is a truthful statement. Saying flex is bad is also a truthful statement. Grabbing onto a statement in a book (or the internet) like "flex is good" and running with it is not the best idea. Not all flex, or all amounts of flex is good. It depends on the amount of flex, where the flex occurs and the purpose of the flex (which is pretty much where I started.)
post #92 of 109
Well, despite the theater not being built to your satisfaction, the rest of the house is looking really nice!!
post #93 of 109

Although, I always thought his and hers showers should be........ smaller wink.gif

Or at least have two drains so that it's clear where all the hair that stops them up comes from biggrin.gif
post #94 of 109
Originally Posted by J_P_A View Post

Although, I always thought his and hers showers should be........ smaller wink.gif

Or, given the size maybe it is a his and hers and hers and hers shower....biggrin.gif
post #95 of 109
Now we're getting somewhere!
post #96 of 109
Originally Posted by rabident View Post

I also saw Green Glue company makes engineered drywall called SILENTFX. I didn't realize there was an alternative to QuietRock. It's basically 2 layers of drywall with the green glue already sandwiched between. Goes on like a single layer of drywall. I don't know the price, but I think anyone that's been through clips + GG + DD with their builder would appreciate the added simplicity. At that point it becomes clips & channel which most drywall crews are familiar with. No issues with 2 screw lengths and the dangers of using the wrong one (which I think is a real issue with drywall crews paid by the job and therefore going 200mph trying to get done and move on). For DIY, I am sure field assembly drywall (FAD) is cheaper and probably performs better. But if you're going to pay someone, you should factor in how well FAD performs on clips while bound to a stud.

The house is really coming along nicely. My wife (and I) give you a big "thumbs up" for the exterior stone work.

While this product category may have started with QuietRock, there are a handful of other companies that make alternatives. National Gypsum makes Gold Bond Soundbreak XP and Suppress Products makes Sound Engineered Drywall (SED) to name two. Although both have a viscoelastic constrained dampening layer, even the price of these "off" brands is phenomenally high vs. standard drywall and Green Glue.

As you point out, your contractor would really have to charge a very high finish rate for the two layers of 5/8" and manual application of Green Glue for the two assemblies to be equivalent financially. But since soundproofing is all about mass, two layers of 5/8" with a Green Glue layer in between will always win vs. a single layer of these integrated soundproof products - with the possible exception of QuietRock 545.

I don't recall exactly, but even if you use two layers of the engineered products to get the extra mass, it is my understanding that the measurable difference between two layers of the engineered drywall and two layers of 5/8" with Green Glue is only a couple of STC points at best. Considering the HUGE upcharge of one vs. the other, it's not money well-spent. A local distributor was clearing out 5/8" Suppress drywall in 4x8 sheets at $46 per sheet vs. the typical $75. A 4x8 sheet of standard 5/8" can be had for only about $8. Even factoring in buckets of Green Glue and a professional contractor's time, it is still difficult to justify the huge differential despite the easier installation of a single layer of the engineered product.
Edited by TMcG - 12/16/12 at 3:53am
post #97 of 109
Originally Posted by rabident View Post

How long is a 2" screw? I know I asked that before, but I don't remember the answer. Is 5/8 drywall really 5/8" wide?
Whisper clip specs list 1 5/8" from the peak of the channel ridge to the stud they sit on. At face value with 5/8" drywall resting on top, that would make 2 1/4" distance to the stud. I was using 1 1/4" for the first layer and 2" for the 2nd. Assuming the wrong screw was used, (2" on first layer) wouldn't the 2 1/4" gap mean the screw couldn't make it to the stud? Or is it possible based on tolerances, flex, and the way they slam the screws in that a 2" screw could catch a stud?

Yes, unlike dimensional lumber, screw length and drywall thicknesses are pretty much spot-on. I would think the only way they could catch a stud is if the wrong screw was used (the longer 2") on the first layer and really, really slammed it home. But even then the screw would barely penetrate the stud. Don't get me wrong, it's still a "short circuit" in the assembly, but the chances are low for any kind of solid connection. I would think your bigger concern at that point would be the lack of holding power of the drywall to the channel since the paper would be completely pierced if the screw was really slammed home. The driving power used to drive home those screws shouldn't be even remotely close to flexing the wall. Plus all those guys use the professional screw guns with the clutch that doesn't allow for any screws to be "slammed home".

Do you think you have a number of "short circuit" connections?
Edited by TMcG - 12/16/12 at 4:38am
post #98 of 109
Two individual layers of drywall plus green glue is a superior approach when concerned about sloppy installation. The two layer+GG approach is reasonably tolerant of installation errors provided the entire first layer is installed prior to the second layer. When installing the manufactured two layer products you cannot stagger, or overlap, the seams between sheets. The failure to properly seal these seams can lead to a significant reduction in assembly performance.
post #99 of 109
Can you still get to the back of that wall? For some reason I'm thinking the adjacent room isn't in drywall.
post #100 of 109
That is now a double wall and doesn't share framing with the theater, the mechanical room is 2 layers 5/8 and green glue.
post #101 of 109
Hmmm. Good to know. I suppose the "best" way to isolate that room would be double drywall and GG on that side as well. I think that's how a lot of the tests are done. Would it be much trouble to have the cables and boxes surface mounted now, or is the room drywalled already?

I know you guys are beyond an joys to move in. Hope you guys get in there soon!
post #102 of 109
Don't overlook the fact that what ever you build will need ventilation. Not because of the heater but also heat generated by the pump.

post #103 of 109
You can always use hardiebacker instead of drywall. It will be more expensive, but it won't matter if it gets wet. Also, you could turn the pump so that the pipes are at 90 degrees to wherever they are going. Come out away from the pump far enough to build an enclosure, then turn the pipes and build another enclosure around that. Sort of a duct muffler for your piping. I would think that rubber isolators or feet would be a good idea.
post #104 of 109
Looks like we've had a long break in the action here. Everything still going as planned?
post #105 of 109
Originally Posted by rabident View Post

In other news, my wife decided she wanted a 900lb fridge at the last minute. Kitchen is over the theater. The 12" OC theater trusses that gave me grief with the HVAC ducts ended up saving the day for her. So that worked out well.

Looking forward to moving in and getting started on the theater.

900 lb fridge? Holy COW!!!!! eek.gif

I thought my wife' 48'' Sub Zero was a beast at a little under 700 lbs.....................what fridge are you talking about?
post #106 of 109
Sorry to hear about all the troubles - they are considerable. Especially your health - obviously that has to be the top priority - you have my best wishes.

I wonder how many people and in how many sessions you would need to get it built by committee of volunteers. I'd imagine there are a number of locals or semi-locals who you could perhaps oversee for a few weekends to get a lot of it done. Do you have a task list for the finishing? With everything spec'ed out already, you might do pretty well to buy supplies and host a few building parties. Just a thought.
post #107 of 109
Perhaps it's little consolation but you're welcome to come over to my place again to enjoy a movie to take your mind off of things. I know my place isn't much by your standards but the beer's cold and the couch is comfy. You wouldn't even have to use the stairs, either!
post #108 of 109
Wow. I hate to hear about the health issues! I've heard of a few people recently with similar trips to the ER for pain that they suspected was gallbladder. Hope you get back on your feet soon!

As far as the theater goes, I think Fred has a great idea. Barring that, you may have to go through a GC. I'd just make it clear that everything is going to be scrutinized heavily!
post #109 of 109
Thread Starter 
I would like to put Big's documentation of my room build in my 1st post since it still represents my current build status. But the forum switches to Rich Text Editor and won't let me post normal content. Anyone know how to disable rich text editing mode?
Originally Posted by BIGmouthinDC View Post

So rabident asked me to come down for a day to supervise the drywalling process. Coordinating with the builder and his subs was not easy, to get them to commit to an exact date was a challenge so I was kind of on standby for the assignment. I got there Monday night and we found two walls without channel so Rabident and I finished what we could with the channel on hand but we were still 3 rows short on one wall. An emergency delivery of another bundle in the morning solved that and by 9:45 am the room was ready to rock. It took awhile to get the guys to down from working on the other floors And we started about 10:15

This is how we started 3 guys, no lift just a couple of ladders. One superman on stilts. One guy on the ground would hand the end up to the guy on stilts another guy would climb a ladder. Holding the drywall up with one hand and with a screw gun in the other the superman fasten his end then walked over and fastened the other. To start the first row they were having problems positioning the first sheet so it wasn't touching the framing and they wanted to do the walls first. So I suggested sliding pieces of drywall as blocking under the channel, installing the drywall then removing the blocking. That worked and everyone was happy.


I started out putting on the Green Glue but it must have looked like fun because by the end of the day all 6 members of the crew (including superman) wanted to take a turn so they could add that to their resume, I was happy to oblige as my hand was getting stiff.


Throughout the day a big concern was were they using the right screws, 1 1/4 for the first layer and 2 inches for the second. First and second layers were going up at the same time in different areas of the room and we kept looking over there shoulders and reminding them and as a final test we pushed the walls to see if they would move without being bound to a stud. It was in this process that I discovered that I could set up a standing wave in the 12 x 30 wall at about 80-100 cycles per minute. When I pushed in the far end would come out and if I did it repeatedly at the right frequency it would oscillate. It did however stop immediately if I stopped pushing.

I think the main room was done by 5pm, basically 6 hours for a 3 man crew before lunch and 6 guys after. The most interesting thing I saw was a kid who couldn't have been more than 150 lbs carrying a full sheet (4x12) in by himself.
Originally Posted by Dennis Erskine View Post

It was in this process that I discovered that I could set up a standing wave in the 12 x 30 wall at about 80-100 cycles per minute.
Well, that's a problem.
Originally Posted by BIGmouthinDC View Post

Ted Thought it was a good thing that it was such a low frequency. It also took about 100 lbs of force and damped immediately when I stopped pushing.
Originally Posted by Dennis Erskine View Post

If that's a load bearing wall, that is a problem.
If that is one side of a double stud wall, that is a problem if the studs contact each other.
I note from reviewing some of the pictures, there is no blocking. In most areas, a 12' wall will require blocking at the 1/3 and 2/3 locations (height).
Originally Posted by Dennis Erskine View Post

Judging from the degree of compression, it would indicate there is very little compression of the clips and channel and the majority of the movement is structural ... which, aside from structural issues is serving to transmit vibratory energy into the structure of the house. That's not too much of a problem if your intent is to keep the room quiet. It is a problem if your intent is to keep the house quiet. (granted, the movement itself is absorbing energy which is a good thing).

I followed my Signature Design framing plans exactly, as I was told was important. The plans did not have blocking depicted between the studs, so I thought it was not supposed to be there. The builder said that normally he would block those walls. I asked him not to, which he was reluctant to do. I doubt he will be willing to hang additional MDF and 2x4 skeleton framing from the existing drywall due to structural integrity concerns.

Trying to see what my options are. I hate to take down the drywall because it was a lot of work to get it up. Could I cut through 2 layers of drywall, add the blocking, then patch it back up?
Edited by rabident - 12/26/13 at 2:19am
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