Quick Answer
Mineral wool and spray foam are the best types of insulation for earth-sheltered homes due to their high R-value and moisture-resistance. These materials help maintain a consistent indoor temperature and prevent moisture buildup, which is crucial in earth-sheltered homes. They also provide excellent thermal performance.
Earth-Sheltered Insulation Considerations
When it comes to insulating an earth-sheltered home, high R-value and moisture-resistance are essential. Mineral wool and spray foam excel in this regard. Mineral wool, for instance, has an R-value of R-3.8 per inch and is available in batts or loose-fill formats. Spray foam, on the other hand, can achieve an R-value of R-6.0 per inch and forms a continuous, monolithic barrier.
Insulation Installation Techniques
Proper installation techniques are crucial to ensure the effectiveness of insulation in earth-sheltered homes. In walls, for example, mineral wool or spray foam is typically installed between the structural framing members. A vapor barrier, such as a 6-mil polyethylene sheet, should be applied to the warm side of the insulation to prevent moisture from entering the insulated space. In crawlspaces, loose-fill insulation is often used, but a vapor barrier should still be installed to prevent moisture buildup.
Rigid Foam and Moisture Control
Rigid foam insulation can also be effective in earth-sheltered homes, particularly when used in conjunction with a vapor barrier. However, it’s essential to ensure that the foam is properly sealed to prevent moisture from entering the insulated space. A minimum of 1/4-inch space between the foam and any adjacent surfaces, such as foundation walls or piers, is recommended to allow for moisture movement.
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