Minimum foam board thickness over OSB

[Arky217]

For a mixed humid climate (Arkansas),
what would be the minimum thickness or R-value of foam board over OSB wall sheathing to prevent condensation in the colder months on the inner surface of the OSB when the wall cavity batts are R-19 ?

Thanks,
Arky

[MountainDon]

References:

http://www.buildingscience.com/documents/houseplans/hp-mixed-humid-recommendations/view?searchterm=mixed%20humid

http://www.buildingscience.com/documents/houseplans/hp-haymount-va-example/view?searchterm=mixed%20humid

http://www.buildingscience.com/documents/houseplans/hp-greensburg-ks-example/view?searchterm=mixed%20humid

http://www.buildingscience.com/documents/profiles/etw-louisville-profile/?searchterm=mixed%20humid

http://www.buildingscience.com/documents/profiles/etw-charlotte-profile/?searchterm=mixed%20humid

A quick look shows 1", 1 1/2" and what appears to be 2".  The houses are all in mixed humid but scattered around. Maybe looking at the degree heatings days, rainfall and whatever in the different locations and comparing to your location in AR will help.   Also there's a link to a book...

Builder's Guide to Mixed-Humid Climates $45

[bayview]

   Really a wealth of information on the Building Science site . . .

   I was surprised that air conditioned spaces shouldn't have any type of vapor barrier . . .    Since A/C dehumidifies the home.

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