# What is a concealed space?



## MikeC (Jul 23, 2015)

Is the area between the roof trusses and a suspended acoustic ceiling considered a concealed space for the purpose of 2009 IBC 719.2.1?

This space was going to be a return plenum.  The contractor and HVAC designer decided to run return ducts instead (without notifying the engineer or me), and deleted the 5/8 gyp board from the bottom of the roof trusses, leaving kraft face insulation exposed.  I am waiting for updated plans from the engineer, but I just wanted to be ready because I think they are going to leave the kraft facing exposed.


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## cda (Jul 23, 2015)

Wood or metal construction?

Sprinkled building ?

What is the flame spread and smoke numbers?


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## steveray (Jul 23, 2015)

719.2.1 Facings. Where such materials are installed in concealed spaces in buildings of Type III, IV or V construction, the flame spread and smoke-developed limitations do not apply to facings, coverings, and layers of reflective foil insulation that are installed behind and in substantial contact with the unexposed surface of the ceiling, wall or floor finish.

Substantial contact is the key....Which I believe is also in the insulation instructions....Sounds like a no-go to me


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## Francis Vineyard (Jul 23, 2015)

Also should the 5/8 gypsum be required for protection or fire-resistance look at Section 803.11 provisions on suspended ceilings.

And yes it is a concealed space.


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## MikeC (Jul 23, 2015)

Wow, don't I feel stupid.  I quit reading before I got to the "in substantial contact with" part.  Thanks.

FWIW, this contractor doesn't like to follow directions.  He has a habit of changing things.  He seems to think that plans are a guideline.


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## fatboy (Jul 23, 2015)

FWIW, I like your signature line, nicely done.


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## Sifu (Jul 23, 2015)

Usually printed right on the paper facing too.


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## kilitact (Jul 24, 2015)

720.2 Concealed installation.

Insulating materials, where concealed as installed in buildings of any type of construction, shall have a flame spread index of not more than 25 and a smoke-developed index of not more than 450.

If the insulation installed in this concealed space meets the flame and smoke requirements, should be good to go.


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## MikeC (Jul 27, 2015)

Thanks all,  I have been in contact with the engineer.  He is proposing the removal of the current insulation and installation of new insulation that exceeds the flame spread / smoke develop requirements.  Even though this is minor, I am half tempted to require a new set of drawings and bill the minimum for a new plan review.  This is the third time the contractor has changed the plans on this job without approval from the engineer or me.


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