Replies

1. 
   calvin | Jun 22, 2007 04:32am | #1

   From what I've read, laying batt insulation above the tiles/grid is really not recommended

    

   no kidding, what's the reasoning behind this?

   A great place for Information, Comraderie, and a sucker punch.

   Remodeling Contractor just outside the Glass City.

   http://www.quittintime.com/

    

2. 
   ponytl | Jun 22, 2007 04:47am | #2

   From what I've read, laying batt insulation above the tiles/grid is really not recommended

   hmmm funny that they sell 2x4 batts for this .... i've moved and placed way more of them than i'd ever wish on anyone... suck azz job...  but done all the time

   p

1. 
   bldrbill | Jun 30, 2007 12:00am | #15

   Thanks ponytl.  I found these things--they're called sonobatts, made by Owens Corning.  They come 3-1/2X24X48 and are made especially for suspended ceilings.

   http://www.owenscorning.com/around/sound/commercial_acoustics/SONOBATT.pdf

3. 
   gstringe | Jun 22, 2007 04:47am | #3

   Even if you never have to go back there, don't lay batts on top of the tile. Any one who ever has to access the area above the lay in tiles hates batts on the tile. Batts are an absolute mess to deal with after they have been installed when accessing the area later. Dirt, dust and insulation down your back, in your eyesblah blah and they never get put back correctly after being disturbed....doooonnnnn't do it.

   Open the ceiling up and spray foam the joist space...end of discussion...

   Nobody gets in to see the wizard...not nobody...not no how!
4. 
   fingersandtoes | Jun 22, 2007 05:53am | #4

   The problem with putting insulation on the suspended ceiling, is that you won't be able the provide an adequate air barrier to prevent the passage of warm interior air into the cold roof space above. It is a recipe for real moisture problems.

5. 
   McDesign | Jun 22, 2007 06:26am | #5

   My personal shop has batts directly above (5-6") a t-bar ceiling with (9) 4-tube troffer fixtures.  Never a problem for 6-8 years.

   Forrest

1. 
   bldrbill | Jun 22, 2007 06:18pm | #6

   I see you're in Georgia.  I'm in Alabama, another high humidity area.  If you haven't had any moisture problems, maybe I won't either.

    

1. 
   McDesign | Jun 22, 2007 06:42pm | #8

   I can take a pic if you'd like, but basically my shop roof has a 2/12 (shed) pitch; unfaced R-19 batts between the 2x6 rafters.  6mil poly stapled up to the underside of the rafters.  The suspended ceiling is also on the same slope, and is dropped down just enough for the top of the ~4" thick troffer fixtures to clear the poly - maybe 5-6" total.

   The poly is as air-tight as I could make it.  No roof ventilation.

   Forrest

1. 
   bldrbill | Jun 22, 2007 09:03pm | #9

   I think I understand what you have.  I at first thought you had laid the batts on the ceiling tiles.

6. 
   DanH | Jun 22, 2007 06:29pm | #7

   Insulation is useless without an infiltration barrier, and a suspended ceiling is a lousy infiltration barrier.

   The "right" answer (ignoring the option of sprayed insulation against the roof sheathing) is probably to completely take down the ceiling, install drywall (possibly with a vapor barrier above it), and then insulate conventionally above the drywall. This option is also the best from a fire-protection point of view (which you should investigate before deciding on any approach).

   Ignoring fire issues, one could probably get away with plastic or insulation mesh stapled to or layed above the joists, with cellulose then blown on top. Would likely be possible without complete disassembly of the ceiling (though all panels and short cross-pieces should be removed during the installation).

   So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
7. 
   Shep | Jun 22, 2007 09:03pm | #10

   We did that years ago in the offices in my church.

   Its gotta be at least 20 years and there's no sign of any damage or degradation.

   We were loosing a lot of heat thru the suspended ceilings, and needed to do something.

1. 
   bldrbill | Jun 22, 2007 09:05pm | #11

   Shep, this is also in a church office.  Did you just place the insulation batts on the ceiling tiles?  If so, did the added weight cause any problems?

1. 
   Shep | Jun 23, 2007 05:49pm | #12

   As I recall, we used 6" unfaced insulation, and they did sit right on top of the ceiling tiles.

   The additional weight was pretty negligible per square foot, so didn't affect the grid.

1. 
   bldrbill | Jun 24, 2007 12:29am | #13

   Thanks Shep.  I'm going to try your method. 

1. 
   Shep | Jun 24, 2007 02:24am | #14

   The worst part is pulling the insulation up thru the grid, and getting it distributed over the ceiling.

   We pulled out 2 tiles on either end of the room, and 2 guys on stepladders worked together to get it done.