# Which side should the insulation paper face



## joetheinspector (Feb 28, 2017)

Where in the  code or insulation installation instructions does it say which side the paper should face?
I have always heard that the paper (barrier) is supposed to face the warm side in the winter which would be the floor side in climate zone 5. Someone has installed the insulation with the paper facing the crawl space side. I have heard that the paper should be facing the floor side. I need a code section or installation instruction section. Does anyone have this??
We are under the 2009 IRC and the 2009 International energy code. Climate zone 5.


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## steveray (Feb 28, 2017)

R601.3 Vapor retarders. Class I or II vapor retarders are
required on the interior side of frame walls in Zones 5,6, 7, 8
and Marine 4.
Exceptions:
1. Basement walls.
2. Below grade portion of any wall.
3. Construction where moisture or its freezing will not
damage the materials.


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## joetheinspector (Feb 28, 2017)

THANKS
do you know where it says anything about floors? Floor to vented crawlspace


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## Paul Sweet (Mar 1, 2017)

Most paper-faced insulation must have the paper in contact with the subfloor or wall finish.  This should be printed on the paper face of the insulation.  IRC R302.10.1

A foil facer often has a flame spread of 25 or less, and is usually allowed to be exposed.  However, it would probably be on the wrong side for a floor anywhere but climate zone 1 or 2.


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## Francis Vineyard (Mar 1, 2017)

Be aware that Foil Scrim Paper (FSK) is not an equivalent approved barrier in leiu of "ceiling, floor or wall finish" that are listed in chapters 5 & 7.

*R302.10.1 Insulation. *Insulation materials, including facings, such as vapor retarders and vapor-permeable membranes installed within floor-ceiling assemblies, roof-ceiling assemblies, wall assemblies, crawl spaces and _attics _shall have a flame spread index not to exceed 25 with an accompanying smoke-developed index not to exceed 450 when tested in accordance with ASTM E 84 or UL 723.

*Exceptions:*

1. When such materials are installed in concealed spaces, the flame spread index and smoke-developed index limitations do not apply to the facings, provided that the facing is installed in substantial contact with the unexposed surface of the ceiling, floor or wall finish.


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## Enrgxprt (Dec 5, 2019)

Where heating degree days are higher, paper always to the warm side. In moist humid climates (think more cooling degree days) paper to the outside and again, the warm side... 

Remember, moisture moves from areas of high concentration to areas of low. If its 95% humid out and 45% in the vapor push is towards the inside. We want to keep the vapor out. If we have central air on inside, we certainly want to prevent the vapor from compensating on the back of our sheetrock. Conversely, in the North East, if we have optimal humidity inside the home during  the winter (40-45%) we want to make sure we keep that off the cold sheathing, so paper inside..


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## mtlogcabin (Dec 6, 2019)

If you did not install a vapor retarder barrier on the floor of the crawlspace then you should install one on the floor joist. The Kraft-faced fiberglass batt will meet a Class II requirement. I don't know if that meets your zone requirements or not.
The key is to not trap moisture I suggest you get a copy of the book below and use it for your area to answer questions you may have about the proper way to install insulation. It varies so much depending on where you are located. If you are not in a cold climate he has other books on the link that may be helpful for where you are located 

R601.3.2 Material vapor retarder class.
The vapor retarder class shall be based on the manufacturer's certified testing or a tested assembly.
The following shall be deemed to meet the class specified:
Class I: Sheet polyethylene, unperforated aluminum foil.
Class II: Kraft-faced fiberglass batts.
Class III: Latex or enamel paint.

https://www.amazon.com/Builders-Guide-Climates-Joseph-Lstiburek/dp/0975512714


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## Enrgxprt (Dec 6, 2019)

One of the best books and most used in my collection...


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