Batt insulation over suspended ceiling

Are there any regulations that address the practice of installing fibergalss batt insulation directly on top of suspended ceiling tiles in a commercial building?

I have seen this and it is frequently done for sound deadening .

Roy Cooke

You may have issues…

As usuall, Roy has been around and is correct in his statement that insulation above suspended ceilings is meant to be installed to increase the STC ratings for multi-level occupancies.

The insulation used should not have a vapor retarder of any kind to the batt insulation, because those retarders are flammable and have to be covered with a fire resistant material.

The batt insulation should be unfaced and can be of various thicknesses varying on the STC required.

Batt insulation above suspended ceilings have been used for years for sound control and is being used a little less in todays economy due to the improved STC ratings of drop in tiles that are available.

The only thing to note in this application would be the facing that might exist such as paper facings or foil facings that can not be left exposed due to fire hazards. Other than that, it can be used for sound or additional insulation supplements.

Marcel :slight_smile: :slight_smile:

WOW! …Marcel fantastic ,
Sorry I will be too busy to write an exam on all this great material.

Thanks for the Plug, yes age does have some small advantages .Cooke


Thnks for all the great info, even though it wasn’t what I had hoped for. I personally hate the practice of installing batt insulation over ceiling tiles. It makes the tiles sag and make my job (electrical contractor) much harder. I was hoping to see that there was a regulation that would impose a life sentence of hard labor to anyone who installed or spec’d the installation.


I apoligize for not informing you on what you wanted to hear.

Unfortunately, there are ways of eliminating sag due to insulation weight on ceiling tiles and yes, it is a pain in someone’s ##s to come back and add electrical complementaries after the fact. I have been there.

It is uncommon today to see this type of Construction due the advancement of Suspended Ceiling Tiles designed for either supplemented insulation or sound control.
As far as I know, there is no Code Section that I can find to make this type of installation to side in your discontent to dealing with it.

I guess you will have to go home itching tonight and did you replace the insulation to it’s original position when you were done installing your wires? ha. ha. Most don’t.

Marcel :slight_smile: :stuck_out_tongue: :smiley: :wink:

Johns Manville has an ecapsulated fiberglass insulation that comes in several forms.

They specify use above suspended ceilings in this application sheet:

See this from the sheet:

ComfortTherm insulation carries a Class A rating (ASTM C 665) for low flame spread and has been classified FHC 25/50 by Underwriters Laboratories, meaning it can be used for some exposed (not covered by gypsum wallboard) applications where permitted by the local building code. See National Evaluation Service, Inc. (NES)
Report No. NER-549 – copies available upon request. Under some conditions, even low flame spread material can burn at a slow rate if exposed to an open flame or other heat sources. Do not use ComfortTherm insulation where encapsulation film will be exposed to sunlight or mechanical abuse.
New Construction
• Wood frame construction – residential homes and light commercial buildings
• Metal frame construction – commercial buildings
• Pre-manufactured homes – modular or manufactured housing
• Suspended ceiling systems – sized to fit above 2 x 4 ceilings
• Interior wall sound control – interior walls and floor and ceiling assemblies (For sound class ratings for
wall assemblies, see the appropriate STC values datasheet for either steel or wood framing.)”

Would this be permissible in a single home residential application? One of the available sizes is 2’x4’ R30 batts for this use, as listed above.

If you are looking for sound proof material, you can use this: sound absorbers. These are available in two different categories, one is wall sound absorber and the other is ceiling sound absorber. They are have similar structure but not exactly the same. Sound absorbers for walls are a green design, environmentally friendly fabric wrapped acoustic absorber panels.