# Insulation Over Ceiling Tiles



## north star (Oct 17, 2019)

*> ? > ? > ? *

I see a lot of construction plans with thermal and \ or
acoustical insulation installed \ laid on top of the ceiling tiles.
I seem to recall that this was not an approved type of installation.

*Q1)*  Is installing thermal or even acoustical insulation on top of
ceiling tiles permitted ?.........If not, please provide the Code section
or sections disallowing this.........FWIW, ...there is no electrical wiring
on top of the ceiling tiles either.

Thank you !   

*< ? < ? < ?*


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## steveray (Oct 17, 2019)

I would question whether or not the acoustical ceiling could support it....Manufacturers installation instructions.

[A] 104.9 Approved materials and equipment. Materials,
equipment and devices approved by the building official shall
be constructed and installed in accordance with such
approval.


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## north star (Oct 17, 2019)

*0 - 0 - 0*

Thank you ***steveray*** !

*0 - 0 - 0*


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## steveray (Oct 17, 2019)

C402.2.2 Roof assembly. The minimum thermal resistance
(R-value) of the insulating material installed either
between the roof framing or continuously on the roof
assembly shall be as specified in Table C402.1.3, based on
construction materials used in the roof assembly. Skylight
curbs shall be insulated to the level of roofs with insulation
entirely above deck or R-5, whichever is less.
Exceptions:
1. Continuously insulated roof assemblies where the
thickness of insulation varies 1 inch (25 mm) or
less and where the area-weighted U-factor is
equivalent to the same assembly with the R-value
specified in Table C402.1.3.
2. Where tapered insulation is used with insulation
entirely above deck, the R-value where the insulation
thickness varies 1 inch (25 mm) or less
from the minimum thickness of tapered insulation
shall comply with the R-value specified in
Table C402.1.3.
3. Unit skylight curbs included as a component of a
skylight listed and labeled in accordance with
NFRC 100 shall not be required to be insulated.
Insulation installed on a suspended ceiling with removable ceiling tiles shall not be considered part of the minimum thermal resistance of the roof insulation.


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## mtlogcabin (Oct 17, 2019)

2012 IEEC
C402.2.1 Roof assembly.
Insulation installed on a suspended ceiling with removable ceiling tiles shall not be considered part of the minimum thermal resistance of the roof insulation.

Installing thermal insulation on removable ceiling tiles does not help with meeting the energy
I could not find a prohibition of using sound insulation on removable ceiling tiles


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## Paul Sweet (Oct 18, 2019)

This was very common back in the 70s & 80s.  The main problem is that the insulation always pushed aside when anybody has to get above the ceiling, and never put back.


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## Rick18071 (Oct 18, 2019)

I have checked the manufacturers instructions on a job and it did not say if it is allowed or not allowed. They were installing  insulation just for sound proofing in the suspended ceiling.

The NEC Handbook commentary 300.4(C) says cables are not to be laid on suspended ceilings because it would inhibit access but there is noting about anything else that could inhibit access.


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## jar546 (Oct 18, 2019)

Then there is the issue with the paper being exposed


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## mark handler (Oct 19, 2019)

Paul Sweet has the answer


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## Builder Bob (Oct 21, 2019)

energy code does not allow it - as stated in an earlier post


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## north star (Oct 22, 2019)

*& * &  * &*

Welcome back JimBob !........I hope that you are doing well. 

*& * &  * &*


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## Rick18071 (Oct 22, 2019)

energy code does not have the answer if the insulation is only used for sound which is what I am concerned about.


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## Paul Sweet (Oct 22, 2019)

It's allowable for sound, but it still gets moved around so it doesn't do much good after a decade or so..


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## Pop Alexandra (May 13, 2022)

Paul Sweet said:


> It's allowable for sound, but it still gets moved around so it doesn't do much good after a decade or so..


That's my experience as well. I usually replace ceiling panels every 10 to 12 years.


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## jj1289 (May 13, 2022)

It must be approved by the manufacture of the ceiling system. Generally if insulation is going to be installed on top of the tiles and grid system, the tiles and grid system have to be specified to support the additional weight.


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## Pcinspector1 (May 13, 2022)

north star, 
One thing to check is if there are troffers or other types of lighting, the troffer light fixture has to have the *IC marking for Insulation Contact*. 

Also the ROMEX KING can't install ROMEX above the grid system in commercial but he can on his residential jobs!


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## ccollings (May 13, 2022)

this is a common practice with open office buildings and is done for acoustics.  use unfaced batts.  what we've done is run the ceiling grid continuous across a space.   at offices, rather than run the walls up to the deck, you use modular walls (Dirtt) and only run them to the ceiling and add acoustic insulation over the ceiling tiles.  these spaces get remodeled every 5 - 10 years, so this allows a lot of flexibility.    it's not my favorite practice but i understand it.


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## Genduct (May 13, 2022)

steveray said:


> I would question whether or not the acoustical ceiling could support it....Manufacturers installation instructions.
> 
> [A] 104.9 Approved materials and equipment. Materials,
> equipment and devices approved by the building official shall
> ...


Depending on Climate Zone, does not good building science say the Air/ Vapor and Thermal Barrier need to be maintained?  I don't think much of the Acoustical ceiling being very effective on the air or vapor part of that statement
So even if the Code Doesn't dis-allow it,  I suspect that Best Practices would not look kindly on installing this as described


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## bill1952 (May 14, 2022)

Genduct said:


> Depending on Climate Zone, does not good building science say the Air/ Vapor and Thermal Barrier need to be maintained?  I don't think much of the Acoustical ceiling being very effective on the air or vapor part of that statement
> So even if the Code Doesn't dis-allow it,  I suspect that Best Practices would not look kindly on installing this as described


in heating climates.


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## Genduct (May 14, 2022)

bill1952 said:


> in heating climates.


Bill. Do you agree that our Mixed Humid zone 4 is probably even more of a challenge?


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## bill1952 (May 14, 2022)

Probably. Block walls and foam insulation.  That was Joe Lstibruk's solution at a conference he was speaking at. I was thinking about OP, and don't know where in the world he is.


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