soundproofing suspended ceilings

  Hello,

     Does anyone have any suggestions on limiting sound transmission
through suspended ceilings?

     I really have two questions:

     A) in a commercial setup where there is suspended ceiling in use
(which means offices are just big cubicles in the building shell
capped off with suspended ceiling) how do you keep noise from
traveling out of a noisy room?  The suspended ceiling does little to
stop the noise from exiting through the ceiling and because there are
no walls seperating the offices above the suspended ceiling, the noise
migrates down into adjacent rooms.

     B) in same scenario outlined above, if you can't stop the noise
at the source can you add something to the suspended ceiling in
adjacent rooms to limit migration of noise into them through the
suspended ceiling?

     For A) I'm wondering if I can't hang egg shell foam sheets above
the walls (in plane) maybe mass loaded with carpet padding affixed to
it.  I don't even no how that would hold up with fire codes.  I have
no idea what fire codes would be like above the suspended ceiling,
whether there are limitations as to what you can put above them.

     For A) I'm considering rolling out insulation over top of
ceiling, possibly egg shell foam properly fire rated (and I'd make
sure I was allowed to do so by code).  Again, I wonder if 'mass
loading' with carpet padding might help?  (And again, of course
there's the fire code allowances to do so.

Dean

 Blow Cellulose insulation on top.  of course if there's mechanical or
electrical to be accessed periodically, that may not be a viable option.

steve

  dean_maiorano@hotmail.com wrote in
com:


There are several issues here.  In most such office areas, the area
above the suspended ceiling is used as a return air plenum, thus
restricting the kinds of things that can be placed there.  I'm
afraid that probably the only kind of insulation allowed would be
enclosed fiberglass batts.  You also have the issues of
requirements for open air spaces around the light fixtures.

If you have only one or two offices that need to be soundproofed
you might be able to get permission to place enclosed fiberglass
bats over those offices only, as long as you make allowances for
return air flow from the office into the above-ceiling area, and
don't cover over any light fixtures.  The best thing to do would be
to contact a building inspector from your local authority and ask
them what would be permissible and what others may have done to
accomplish the same task.

 As tim has already said, the major consideration is the routing of
return air if it is a plenum return.  One of the best solutions if
you have a ducted return would be to extend drywall to the deck
around the problem area.  Additional layers drywall and addition
of sound panels to the isolation wall will increase the isolation.
Contact a local drywall supply house and investigate sound board -
a brown cellulose sheet product that can be cut into grid sized
pieces.  It will double the weight of the  drop ceiling, so make
sure the hanger wires are adequately spaced and in good repair.



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DanG  (remove the sevens)
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 On Jan 17, 10:11 pm, dean_maior...@hotmail.com wrote:

How much noise is it, is it talk level or jackhammer. anything can be
sound proofed but cost is determined by db level. Radioshack has db
meters, then you will know what to do by a rating, db = decibel.