(1) Plain concrete foundations.- Concrete in plain concrete foundations shall be proportioned and mixed in accordance with the provisions of Chapter 3.

(2) When flexural calculations are made, a plain concrete foundation shall be designed on the assumption that critical sections are at the face of the wall, pier or column which it supports, and, in a stepped foundation, also at the face of each step.

(3) A foundation referred to in subsection (2) shall be so proportioned that maximum tensile stress at any critical section will not exceed 0,03 times the design 28-day compressive strength of the concrete, shall be determined in accordance with the provisions of Chapter 3.

(4) When flexural calculations are not made, the ratio of the vertical thickness of any plain concrete foundation to its maximum projection beyond any face of the wall, pier or column which it supports, and the ratio of the depth to the projection of any step the cross-section of the foundation, shall be not less than 1,5, if the bearing pressure on the subsoil is not greater than 300 kilopascals.

(5) If the bearing pressure is greater than 300 kilopascals, the ratio specified in subsection(4) shall be increased by a minimum value of 0,1 for each increase of 50 kilopascals or remaining part thereof over 300 kilopascals in the bearing pressure under the foundation.

(6) For plain concrete foundations supporting columns and sleep-piers, the punching shear stress calculated on the area obtained by multiplying the perimeter of the column or sleep-pier by the thickness of such foundation shall not exceed 0,06 times the design 28-day comprehensive strength of the concrete determined as described in subsection (3).

(7) Plain concrete foundations are permitted to be constructed in accordance with the empirical rules set in section 22.

(8) Reinforced- concrete foundations. – Reinforced-concrete foundations shall be designed and constructed in accordance with the provisions of Chapter 3