earth roof

sod roof

A roof composed of a thick layer of grassland containing roots; frequently pitched or barrel-shaped and supported by logs; usually prone to problem of water leakage. In sod houses of better quality, the sod roofs were covered with shingles (which were then covered with additional sod to prevent the shingles from being blown away). In upscale modern sod houses, an impermeable plastic sheet is set beneath the sod roof to reduce or eliminate water leakage.