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Bay Area Moisture Control Meets or Exceeds all California Building Codes

California Building Codes We are a certified bonded and licenced contractor (CA Lic# 72630) that meets or exceeds California Building Codes.

BAMC, Inc. will install a liner that is 20 mil thick and similar to a pool liner. The top edge of the CleanSpace membrane is sealed to the walls with polyurethane sealant. All seams are sealed with a special sealant and 4 inch wide tape made especially for the CleanSpace membrane. BAMC, Inc. seals the polyethylene to the top edge of the foundation wall.

A properly sealed, moisture-protected, and insulated crawlspace will increase comfort, save on energy costs, improve the durability of the home, and reduce entry of moisture, radon, and other potential irritants or pollutants into the home. Whichever design is followed, the keys to an effective crawlspace are:

Moisture control – using a water-managed foundation system to drain rainwater and groundwater away from foundations.

Airtight construction – sealing all air leaks between the conditioned space and the outside prior to insulation installation.

Complete insulation coverage – properly installing the correct insulation levels and making sure the insulation coverage is continuous and complete.


A crawlspace is susceptible to moisture and deterioration problems because of contact with the earth. The best approaches for preventing these problems will depend on the local climate and style of construction, but the following general rules apply to most crawlspace designs.

  1. Keep all untreated wood materials away from the earth.
  2. Provide rain drainage, such as gutters, to conduct rainwater away from the house.
  3. Slope the earth away from the house for at least 5 feet at a minimum 5% grade (3 inches in 5 feet). Establish drainage swales to direct rainwater around the house.
  4. Add a sill gasket to provide air sealing.
  5. Install a protective membrane, such as an EPDM-type membrane, to serve as a capillarybreak that reduces wicking of water from the masonry wall. This membrane, in addition to metal flashing, can serve as a termite shield.
  6. Dampproof the below-grade portion of the foundation wall to prevent the wall from absorbing ground moisture by capillary action.
  7. Install drainage plane material or gravel against the foundation wall to relieve hydrostatic pressure and channel water to the foundation drain.
  8. Provide a foundation drainage system at the bottom of the footing, not on top, when the foundation floor (interior grade) is below the exterior grade. Surround a perforated 4-inch drain pipe with gravel and cover them with filter fabric.
  9. Install 6-mil polyethylene across the crawlspace floor to prevent soil moisture from migrating into the crawlspace. Overlap and tape all seams by 12 inches, and seal the polyethylene 6 inches up the crawlspace walls.

Source: Office Of Building Technology, State and Community Programs
Energy Efficiency and Renewable Energy * U.S. Department Of Energy

For more information visit http://www.bsc.ca.gov/default.htm

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