# vapor retarder - when required in IBC 2006



## syarn (Nov 12, 2010)

in northern USA buildings; when does the IBC 2006 require the vapor barrier on the "warm side" of the exterior wall to control moisture?

chapter & verse please.  thx u.

it seems to me that zone 4c Marine is southernmost climate that the code calls for the vapor retarder per IBC 2009 section 1405.3 vapor retarders....

is there an online tool or calculator that goes beyond the code and analyzes when the vapor retarder is of value?


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## Examiner (Nov 12, 2010)

http://www.buildingscience.com/documents/digests/bsd-106-understanding-vapor-barriers/?topic=/designguidance/buildingscienceanddesign/walldesign/main_topic

a good site with lots of free info


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## syarn (Nov 16, 2010)

thank you very much


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## Architect1281 (Nov 16, 2010)

NOT in IBC but in IECC here

502.5 Moisture control. (Mandatory).

All framed walls, floors and ceilings not ventilated to allow moisture to escape shall be provided with an approved vapor retarder having a permeance rating of 1 perm (5.7 × 10 –11 kg/Pa · s · m2) or less, when tested in accordance with the dessicant method using Procedure A of ASTM E 96. The vapor retarder shall be installed on the warm-in-winter side of the insulation.

Exceptions:

1.	Buildings located in Climate Zones 1 through 3 as indicated in Figure 301.1 and Table 301.1.

2.	In construction where moisture or its freezing will not damage the materials.

3.	Where other approved means to avoid condensation in unventilated framed wall, floor, roof and ceiling cavities are provided.


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