Closed Crawl Space Assemblies

For years common construction practices and building codes required that crawl spaces be ventilated to the outside for the intended purpose of reducing moisture under a structure.

Research indicates crawl spaces ventilated to the outdoors do not function as intended, allowing instead for humid outdoor air to come into contact with cooler surfaces under a home to form condensation and to trap moisture.

Services We Offer

Evergreen is a professionally trained installation contractor of closed crawl space assemblies that offer a code-accepted method of properly weatherizing the crawl space, reducing moisture content and improving energy efficiency by eliminating and reducing air and vapor infiltration in the crawl space.

• Damp Proofing involves the application of a minimum 6-mil plastic vapor retardant material to the inside of the foundation wall to help reduce and control moisture infiltration.
• Insulated Foundation Wall involves the installation of rigid foam board insulation using powder loaded nails and special washers over a vapor barrier on the inside of the foundation wall. According to code, the foam board must provide R-10 insulation value to eliminate insulating the floor joists.
• Closed Crawl Space Floors involves the application of a minimum 8-mil plastic vapor barrier on the crawl space floor using special sealing tape at each seam to seal out moisture from the ground. In new construction, Evergreen installs a temporary, sacrificial vapor barrier during construction which is replaced with a final, sealed layer of plastic once the structure is complete. This helps reduce potential effects of moisture on construction materials, discourage mold and pests and significantly improve indoor air quality.

Benefits

• Energy Efficient – Provides greater energy efficiency by helping to create a sealed envelope, limiting air and vapor infiltration in a home or building
  
• Improved Air Quality – Improves quality of indoor air by reducing moisture, humidity, dust and allergens from entering the building envelope
  
• Reduced Moisture – Controls moisture, limiting condensation in a crawl space and the structure above it
  
• Inhibits Mold & Mildew – Maintains humidity levels at appropriate levels, inhibiting ability of mold and mildew to form or grow
  
• Increased Comfort – Improves performance of HVAC system and helps reduce infiltration and duct loss
  
• Reduced HVAC – May result in lower HVAC loads and smaller HVAC system requirements
  
• Reduced Costs – Eliminates need to insulate floor joists or provide foundation vents, and helps reduce the costs of heating and cooling

Design Illustration

The following architectural detail illustrates a complete closed crawl space assembly:

Source: Advanced Energy, Closed Crawl Spaces (2005)

Grading & Drainage

Evergreen installs closed crawl space assemblies that rely on the proper grading and drainage of a jobsite by an experienced grading contractor. Evergreen’s closed crawl space vapor barriers can be very effective at reducing moisture, but they are not designed to protect against storm water run-off, floods or other significant water inundation.

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