Single Family

7. Healthy Living Environment

7.11a Basements and Concrete Slabs: Vapor Barrier

Mandatory

Provide proper drainage to the lowest level of concrete. Waterproof exterior of foundation walls, and provide vapor barriers under all slabs.

Green Communities and the Green Communities Criteria are a national initiative of Enterprise Community Partners to transform the affordable housing sector. For more information go to www.greencommunitiesonline.org

Important Considerations

Codes and Regulations

IRC: 506.2.3 Vapor retarder.
A 6 mil (0.006 inch; 152µm polyethylene or approved vapor retarder with joints lapped no less than 6 inches (152 mm) shall be placed between the concrete floor slab and the base course or the prepared subgrade where no base course exists.

Exception: The vapor barrier may be omitted:

  1. From garages, utility buildings and other unheated accessory structures.
  2. From driveways, walks, patios and other flatwork not likely to be enclosed and heated at a later date.
  3. Where approved by the building official, based on local site conditions.

Note that the Green Communities' overlap requirement is greater than the code requirement. (12" versus 6")

Specifications

03 30 00 (03300) Cast-in-place Concrete
Specification of vapor retarders should be included as part of the materials and methods section for concrete slabs. Specify lapping and seal requirements in cast-in-place concrete installation instructions (for slab-on-grade).

The information above refers to the Construction Specification Institutes (CSI) MasterFormat. The numbers listed above refer to some of the most relevant but not all of the possible MasterFormat sections related to this strategy. The 6-digit numbers refer to the newer 2004 MasterFormat edition. Numbers in parenthesis refer to the older 1995 edition.

Other Resources

Publications and Links

See full list of recommended resources and links in our library.

Related Strategies

W1b: Manage site and stormwater through design
Q1a: Eliminate sources of indoor air pollution
M1: Do a durability plan

Related Scales

Assembly