A sod shelter (or turf house) is strong and fireproof. A framework covered with sod provides a shelter that is warm in cold weather, and one that is easily made waterproof and insect -proof in the summer.
The framework for a sod shelter must be very strong, and it can be made of logs, driftwood, poles, etc. You should use sod with a heavy growth of grass or weeds should be used since the roots tend to hold the soil together. Cutting about 2 inches of soil along with the grass is sufficient. The size of the blocks is determined by your strength.
Your sod shelter can be excavated as well. The sunken floor of the shelter helps moderate temperatures, with the mass of the ground serving as an insulator.