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Discussion Starter · #1 ·
Hey all,


I have been searching for an answer to this on the forum for a bit, but have come up empty. This room is being built in a basement with a drop ceiling (many wires and one bloody unmoveable pipe above). When the wall studs go in, they will need to be anchored to the floor (duh ;-) and the floor joists to the main floor above.


My question is what can be done to minimize the sound transmission to the floor above through the top plate and floor joists? I already have double walls, double drywall, etc. planned into the room. Certainly some acoustic sealant will help, but I fear a lot of bass energy leaking to the floor above. Any ideas from those that have built rooms like this?


Thanks.


Sand
 

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The drop ceiling is the best bet. A true drop ceiling with heavy insulation between might work well or a dropped joist (room within a room idea) so that eh dry wall does not come into contact with the actual floor joists from above.


I have just completed the 5/8ths layer of rock and sealed the @#$$ out of the place. Very depressed when my 3 year old daughter walks across the dining room floor above (hard wood) and I hear every step. I am sure the next layer of 1/2 will help a bit but not resolve. Sound will transmit right through those joists if you couple the ceiling to them!


Others with much more experience will be able to better help your specific needs. If I had a larger room to begin with I would have done the room within a room!
 

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Discussion Starter · #3 ·
Hey,


I am more concerned with sound going up than down. ;-) I plan on putting insulation in the joists and such to keep noises coming in through the ceiling of the HT. It is the bass moving upstream that worries me.


Thanks and take care.


Sand
 

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I understand.... I STUFFED 2 layers of R23 between the floor joists (basically 20 inches of insulation in a 10 inch cavity. Hope that does the trick. Good luck with the room!
 

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Sand,

While the replies thus far contain valuable information, your question is not about the ceiling, but the junction of the overhead floor joists and top of the wall, correct? I too, was trying to come up with a solution to this exact problem yesterday. What I came up with is to isolate the top-plate from the joists with something like ASC Walldamp or Auralex U-Boats and then construct the wall tightly between the slab and this top plate with mechanical fastening only between the two top-plates. Iam going to try to reach both companies today to speak with them about this.
 

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Discussion Starter · #6 ·
Yep - what I am concerned with is sound travelling up through the wall and top plate into the floor joists of the main floor.


For the stabiliy of the wall there has to be a connection there. Question is how to construct it so the sound transmission through that juction is minimized.


Take care.


Sand
 

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It's safe to say that you're not going to install a floating ceiling, right? By that I mean new joists below or in between the existing joists. From the sounds of it the pipe there now is cusing problems and cannot be moved easily. The floating ceiling really provides a great deal of de-coupling, which is what you're after.


If you cannot install a floating ceiling then your concerns about sound transmission are completely valid. Sound will travel up those walls and into the existing floor joists like crazy. There's not a great deal you can do. Even with a gasketing material sandwiched in between the top plate and the joists you'll still have a nice transmitter... the screw. But this scenario is about your best option. Personally, I'd build the walls 1" short of the existing joists. Every 6' to 8' I'd use a 1" gasket and a single screw. Fewer contact points is your best hope, in my opinion.


The walls, once drwalled will be quite stiff and just a few properly placed screws should keep it quite solid.


Ted
 

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Discussion Starter · #8 ·
Ted,


Thanks - that sounds like good advice. Your assessment of the problem is right on. I would love a floating ceiling. It is just not possible. When the house was built, the plumber decided to put the main sewer pipe *through* one of the main supporting members of the main floor. That combined with the mandatory 6 degree grade (maybe 7, not sure), makes movement of the pipe an extremely costly proposition.


The expense is just not worth it in that case. I am already moving the air conditioner - that is expensive enough. LOL


Thanks for the note.


Sand
 

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You are building a room in to an existing space, right? You are not replacing existing walls?


If this is the case then the walls need not be load bearing so they need not be coupled to the ceiling in any way. You should consult a contractor familiar with building codes in your area of course, but it seems reasonable.


The issue would be whether or not the new walls are stable enough without coupling to the rest of the structure. What you gain in decoupling to the ceiling you may lose in lack of stability.
 

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Sand,

I have found our holy grail, that is if you are building your walls along the inside of concrete/masonry walls as I am. I found a Decoupler Clip which attaches to the studs or top plates and then anchors to the concrete wall, yet it is designed such that the two surfaces are acoustically decoupled. I will build my walls a half inch or so shy of the joists and then stabilize the wall by anchoring with these at the top every four feet or so. You can find these at www.silentsource.com the product is RISC-DCxx, Resilient Sound Isolation DeCouple Clip.
 

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Discussion Starter · #11 ·
Scott,


It is not a load bearing wall. However, with 2 layers of drywall (and a 20ft length in the long direction), a freestanding wall is a no-go. If not anchored it will sag.


dkramer3,


Thanks for the link. I am looking at it now. I have 1 wall where I can use this against a masonry wall. Three where I cannot, though. Looks like that Chase wall brace will work for the other walls, though! Kinda pricey, but at this stage what's another 100 bucks? LOL


Thanks!


Sand
 

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Sand,

I have been looking at this some more, and this same clip may work on your other walls as well (I have one like that). My thought is to attach the flange to the joist and then anchor to the top plate. Should work rather well.
 

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Discussion Starter · #13 ·
dkramer3,


You are right. I can likely use either the Resilient Sound Isolation DeCouple Clip or the Resilient Sound Isolation Chase Wall Brace depending on the situation. I think those will work. It may not be perfect, but it is a darn sight better than a solid screw.


Thanks a ton for the link. I am going to forward that over to the guy helping me frame up.


Take care.


Sand
 

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This clip seems like the ticket! While not an absolute de-coupling, it is better than a screw. Did I just say that??? ;)


I might order one to inspect.


Ted
 

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So did anyone try any of those Decoupling clips out yet? Just stumbled across this thread on a search of floating ceilings. Ceiling height and obstacles (as well as complexity) prevent me from going the floating ceiling route. These look promising, but being the newbie I am, I don't really understand exactly how you would use them best to do the stud to joist connection?


Here is a direct link to those products:
http://www.silentsource.com/rsic_prods.html
 

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attach the new walls to the cement walls and floor only with side braces -put some rubber where new wall meets upstairs floor joists(no screws)-snuggly fit them

then tie your free standing wall to the new end walls

tie all coners with cuts about 4 feet in from each corner on the top and if its a long run cross brace too from side to side you can hide this when ceiling is in

this will make a freestanding box

use a accustic pannel in your drop ceiling

this works nice
 

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I purchased one of those RSIC clips but decided not to go that route. I too am building (paint goes on Tuesday) a HT in my basement. I wasn't concerned about sound going out the "side walls" but:

1. Going up through all the HVAC piping in my basement to all the rooms of the house.

2. Going up through the floor above and my wife telling me to "turn it down" (I watch movies 10pm-3am when I can...).

I ended up putting up standard walls (ie. top plate affixed to bottom of floor joists) and filled the bays with natural cotton fiber insulation

( http://www.bondedlogic.com/UltraTouchMain.htm ) which has better acousitcal properties than standard glass insulation. This was followed by 1/2" Celotex SoundStop board then 1/2" rock. I insulated the drop around my HVAC main/return and put 1/8 SoundCor vinyl on the drop as well as the rock.

I now listen to music at an acceptable level while my wife sleeps and she doesn't hear a thing (bedrooms on 2nd floor) so it meets my needs.

FWIW, you could do a "floating wall" of sorts where the top plate sits 1/4" off the joists. You then drill holes in the top plates and screw carriage bolts into the joist bottoms so the wall is supported vertically but not physically touching the floor joists (ie. the wall could "ride" up & down these bolts 1/4" to 1/2" at most). This is done in extreme climates where drastic temperature changes cause a lot of heaving but would also work to decouple walls from floor joists. Ceiling would have to be a drop then.

Good luck,

Warren Briggs

Toms River, NJ
 

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Discussion Starter · #18 ·
Jeraden,


I have studded in the room with the RSICs. They do seem to dampen vibrations. Ended up using 24 for a 21'x13' room. The suppot is very solid. I do have some pictures - I'll have to post them at some point.


I don't know if it is a perfect solution, but it is better than a straight connection, to be sure.


Sand
 

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I just started framing and found this post. I am building a floating floor in the basement. This should prevent subwoofer vibration from reaching the walls. My current framing has the top plate of the 2x4 attached to the joists of the ceiling above. Does a 10" subwoofer really move enough air to move the sheetrock and joists to transfer to the floor above?
 

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Think of it this way. If you knock lightly on a regular wall can the person on the other side hear it? The reason the knock travels so easily is because the sound travels through the studs and out the other side of the wall as they are all connected. The knock is a lot less energy than the subwoofer will be putting out.
 
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