surrounding ground. For instance, concrete and reinforced masonry, wood, and steel are all viable materials. Concrete is the most common choice for constructing earth-sheltered buildings due to its strength, durability, and fire resistance. Cast-in-place concrete is employed for non-critical structural elements such as concrete foundations, floor slabs, and exterior walls with less than of earth cover, while precast reinforced concrete can be used for floors, walls, and roofs. Concrete masonry units should be or greater, with the use of “A” or “H” facilitating unit placement around vertical reinforcing bars, depending on the required structural integrity. It is typically advised to use Type S mortar, grout with a minimum strength of , and a concrete slab with a minimum strength of and thickness. Brick or stone masonry reinforced with steel bars can be utilized for walls that will be subjected to lateral or vertical pressure from earth cover. Masonry generally costs less than cast-in-place concrete. Wood can be widely employed in earth-sheltered buildings for structural and internal work, including floors, roofs, and exterior walls. However, wooden frame walls, which must endure lateral pressure, are limited to a burial depth of one story when used as a structural material. Beyond this depth, the cost will rapidly increase while using wood as a structural material. Although wood can be less expensive than other materials, it lacks steel's strength, therefore it might not be the ideal option for structural material in some earth-sheltered dwellings, especially in moist soil type. Steel is used for beams, columns, bar joists, and masonry reinforcement. The advantage is that steel has high tensional and compressional strength, while the disadvantage is that it must be protected from corrosion if it is exposed to air, water, or other chemicals. It must be used effectively because it is also expensive. Excavation In earth-sheltered construction, there is often extensive excavation done on the building site. An excavation several feet larger than the walls' planned perimeter is made to allow for access to the outside of the wall for waterproofing and insulation. Foundations Once the site is prepared and the utility lines installed, a foundation of reinforced concrete is poured. The walls are then installed. Usually, they are either poured in place or formed either on or off-site and then moved into place. Reinforced concrete is the most common choice. The process is repeated for the roof structure. If the walls, floor, and roof