Crawl Spaces

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.

However, subsequent research indicates crawl spaces ventilated to the outdoors do not function as intended, and instead allow humid outdoor air to come into contact with cooler surfaces under a home. This then allows condensation to form and trap moisture.

Services offered by Evergreen Foam & Insulation

Evergreen Foam & Insulation is a professionally trained installer 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 and piers 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 10-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, we install 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 the potential effects of moisture on construction materials, discourage mold and pests and significantly improve indoor air quality.


  • 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 the need to insulate floor joists or provide foundation vents, and helps reduce the costs of heating and cooling

Grading & Drainage

Evergreen Foam & Insulation installs closed crawl space assemblies that rely on the proper grading and drainage of a job site by an experienced grading contractor. Our 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 sources.

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