What Are Common Mistakes When Waterproofing Earth Shelters?

Insufficient Site Preparation

When building an earth berm home, it’s crucial to properly prepare the site before excavating. This includes compacting the soil to prevent settling, grading the site to ensure proper drainage, and applying a geotextile fabric to prevent soil erosion. The site should be sloped to direct water away from the structure, with a minimum slope of 1:10. Additionally, any areas with standing water or prone to water accumulation should be identified and addressed before construction begins.

Inadequate Waterproofing Materials

Using the right waterproofing materials is essential for protecting an earth shelter from moisture. A combination of a geomembrane liner, a drainage system, and a waterproofing coating can provide adequate protection. The geomembrane liner should be a high-density polyethylene (HDPE) or polypropylene (PP) sheet with a minimum thickness of 20 mils. A drainage system, such as a French drain or a perforated pipe, should be installed to direct water away from the structure. The waterproofing coating should be a high-quality, elastomeric material that can expand and contract with the structure.

Hydrostatic Pressure Management

Earth shelters are prone to hydrostatic pressure, which can cause the structure to fail if not properly addressed. To manage hydrostatic pressure, a drainage system should be installed to direct water away from the structure. The drainage system should be designed to handle the maximum expected water pressure, which can be calculated using the formula: P = ρgh, where P is the pressure, ρ is the density of water, g is the acceleration due to gravity, and h is the height of the water column. A minimum of 6 inches of drainage material should be installed around the structure to ensure adequate drainage.