Mud-bricks are made out of earth and sand, that is mixed with water and shaped with moulds. Then these bricks are laid out in the sun and dried. As all the elements used for the preparation of the mud-brick is natural and costless, the mud-brick comes out to be a very low cost material and fully friendly with the natural environment, which means no pollution of the earth.
The mud-bricks are only capable of taking compression loads that means no shear force or bending can be applied to them. By this, the mud-brick roofing can only be in forms of domes and vaults. The vault is made in the shape of a parabola thus eliminating all bending and allowing the material to work under compression. There is not any problem in walls as bending and shear does not exist.