Cm high, if sand

At the bottom of the pit, a pillow of sand 20-25 cm high, if sand soil must be poured with gravel and pour bitumen. Then a solution of concrete is prepared from sand and cement and poured to the ground. After hardening on the pillars of concrete, put a brick, holding the level of horizon. Calculate the pillars so that the floor level is below the floor of the house by 15-20 cm. Throughout the area of ​​the veranda, a expanded clay layer is poured between the earth and the floor to protect the structure from humidity. After solidification of the solution, we proceed to install the frame.

SRC = "