Should Exterior Walls Have Vapor Barrier In Texas?


What we use in Texas is a moisture barrier and it goes behind siding or brick to keep any of the wind-driven rain from getting to the structure. That’s the place it is used. Vapor barriers are never used in this climate. … So, that is where a true vapor barrier is used on the inside of homes in very cold climates.


The vapor barrier should be installed on the exterior side of the wall. This would prevent moisture from entering the shed and causing damage. Whereas in the cold climate of the north the vapor barrier needs to be installed on the interior wall, or the warm side of the wall.

Should You Install Vapor Barrier on Crawl Space Ground

Frequently Asked Questions

Is a vapor barrier required by code?

The International Residential Code (IRC) requires either a Class I or II vapor retarder on the interior side of frame walls in climate zones: 5, 6, 7, 8 and marine 4 (see climate zone map).

Where does vapor barrier go in Houston-greenbuildingtalk?

Putting a vapor retarder on the interior would INCREASE rather than decrease the potential for mold & moisture problem in the stud bays, whereas with EPS on the exterior and standard latex paints on the interior the moisture from exterior drives will pass through the wall without collecting in any of the layers to cause a problem.

What kind of insulation should be used on vapor barriers?

The rigid insulation installed on the interior should ideally be non-moisture sensitive and allow the wall to dry inwards – hence the recommended use of vapor semi permeable foam sheathing.

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