Hanging the hangers!? :?

Sen · Post by **Sen** » Wed Jul 07, 2004 2:57 pm

Hello Steve and everyone else,
I'm in a bit of a doubt how to hang my acoustic hangers off the ceiling.
the studio's outer shell is finished and I should start with the inside construction soon. The situation with the ceiling at present is: (well there is no ceiling actually, but here goes)
I have (from outside in):
-roof tiles
-battens
-thermal foil insul.
-rafters

rafters are on 600mm centers (sorry about the metrics) and 200 wide.
My current "ceiling" is not sealed of course, so I can't count it as a leaf
of mass.What i will do is add two leaves of mass (with an air cavity in b/ween) before I start wit the inside treatments.
I was planning to put a couple of layers of plaster board just below the foil insul. which would have to be 550mm wide to fit b/ween the rafters. Seal that up and i will (hopefully) have my first leaf of mass. Then i would attach RC to the bottom of the rafters and another couple of layers of plaster screwed to RC. That would leave me with about 150-170mm of air gap (with insulation) depending on how far down the first leaf of mass comes.
Now my problem is: how do I attach the hangers to this ceiling??

I've been following the sticky "floating floor over basement concrete" in which Steve suggests that hangers should not be fastened through the layers, nto the RC and hang off that. I totally agree with this, because these things will have a bit of weight in 'em. For my circumstances, the free-standing stands that Steve suggests will be impossible because in that case I would have the stand legs all over my control room

.
How can this be done without shorting out two leaves of mass up on the ceiling??
I was thinking to put the RC on closer centers (what distance would be good?) n to do the second leaf of mass out of some denser and havier material than plasterboard. (chipboard??)
In that case I thought maybe I would be able to screw the hanger chains into the chipboard but missing the RC above so that I don't short anything out. I know this may require a hard ceiling which would be attached to closely spaced RC, but would it do the trick??....Or am I just crazy in assumptions that it would??

Please help me in my planning, because i would like to have everyhting planned out before i start doing anything inside.
Thank you so much everybody

Post by **Aaronw** » Wed Jul 07, 2004 11:41 pm

Hello Sen,

The problem w/ hanging the hangers from the ceiling or RC, is that the additional weight of the hangers will will pull the RC past it's load capacity and short out the isolation. The RC will no longer be a "spring" to absorb the transmission of sound.

As far as the framing that Steve is suggesting on the thread, as well as what's happening in my CR, is those area's will be part of the framing of the inside splayed walls for acoustical purposes, etc. and won't even be seen. I haven't started mine yet, but I have a thread under the acoustics forum & there is another thread I recently found under the construction forum that has a lot of pictures.

http://johnlsayers.com/phpBB2/viewtopic.php?t=1453

http://johnlsayers.com/phpBB2/viewtopic ... c&start=22

Hope this helps.

Aaron

Sen · Post by **Sen** » Thu Jul 08, 2004 1:36 pm

Hi Arron,
Thank you for your reply. I've been following your "sticky" and conversation with Steve. The place looks great...good luck with everything else.
I have also seen the thread you started about the hangers in which Thomas suggests that they're to be hung off the joists (or roof rafters in my case). I'm putting the RC on the rafters and then the inside ceiling layers to isolate them from the rafters and the upper ceiling mass leaf. So if I go direct into the rafters I will loose the isolation that my RC will provide. A bit of a brain teaser

I did realize that your stands for the hangers will be in the walls behind the soffits basically.
See, I've got heaps of room between my ceiling and the false ceiling in the CR and would like to utilize that space for my hangers, but .....
I've hardly slept last couple of nights trying to figure out how to dp this

Post by **Aaronw** » Fri Jul 09, 2004 4:07 am

What do you have along the walls in terms of construction? You could probably run a 2x4 up along each side and have a 2x4 going across the span of the room (don't know how wide it is?). Don't attach the 2x4 to the ceiling and suspend the hangers off of the 2x4.

Doing the same thing, use 4 total (2 on each side) spread apart, and above the false ceiling, you can have 2 spans, then use cross supports, basically making a frame to support multiple hangers.

Don't know if that made since, if not let me know.

Aaron

Sen · Post by **Sen** » Fri Jul 09, 2004 9:47 am

Hi Aaron,
thanks again mate. Your post did make sense and I was thinking that I would have to do something like that if I can't come up with a better (easier) solution and just hang them off the existing ceiling.
My room is 4.5m wide (about 15') and I think I could get away with some 2X4 trusses, cross-braced, but it would create a whole lot of extra work that I wasn't planning on doing

. Anyhow, if I don't come up with anything else that would have to be the plan!
If anyone else has any other ideas, please feel free to chime in
thanks a lot

Sen · Post by **Sen** » Fri Jul 09, 2004 8:14 pm

Steve...anyone...any ideas on this one??

thanks

knightfly · Post by **knightfly** » Fri Jul 09, 2004 8:33 pm

Sen, one way to do this - space your RC closer together (calculate the extra weight and compare to extra layers of plasterboard) then, try to hang your hangers so they span several RC's - this way, the extra weight will not pull the RC out of useful range.

The only other problem might be sealing - all fasteners (for the hangers) need to go into RC, and will impinge on your air cavity between leaves - as long as you use standard drywall screws for steel studs and screw into the RC, your insulation between leaves will keep any extra penetrations from making much of a difference in isolation.

The basic concept is not unlike a heavier car needing stiffer springs - only instead of stiffer, you just use MORE of them (as in, closer spacing)

Because of the limitations of this method, you probably will want to choose lighter material than MDF for your hangers, though... Steve

Sen · Post by **Sen** » Fri Jul 09, 2004 8:47 pm

Steve, thanks very much...I was waiting for this sort of a comment because that's what I really wanted to do..just screw them up into the RC without building any separate frames or stands.
Now when you say ""try to hang your hangers so they span several RC's"" do you mean for instance hang one chain off one RC and then the other off another piece of RC?..instead of just hanging the whole hanger on the same RC?
BTW, what would you suggest as a lighter material than MDF without compromising too much of good acoustical properties?
thanks very much Steve

knightfly · Post by **knightfly** » Sat Jul 10, 2004 9:28 pm

Yeah, if you have hangers spaced very close you'd want to run them perpendicular to the RC, or you'd be stuck with one every 16" or 24" - not too well packed that way.

Lighter than MDF - either plywood or Celotex/Homosote - either wrapped in fiberglass insulation. 1/2" MDF weighs about the same as 5/8 wallboard, so if you were to use that heavy a material you'd need to calculate just how much more weight you were placing on the RC grid - even the Celotex might be pushing it a bit in some cases.

Here's a pic just in case I wasn't clear enough - keep in mind, though, that any vibration the hangers transmit to the chains will weaken your LF isolation in the ceiling a bit... Steve

Sen · Post by **Sen** » Sat Jul 10, 2004 11:23 pm

Steve,
this seems like my only way to go. I'll try it.
thank you very much for your help. It's greatly appreciated

all the best