Leaderboard

A minor clarification , 9 inches is for RCC footings on soil, as per ACI 2011 15.7, minimum depth of footing above bottom reinforcement for footing on soil should be 6 inches, while for footing on piles should be 12 inches. So by adding dia and cover to reinforcement, minimum depth of RCC footings on soil comes to 9 inches, while for footing on piles it comes to 15 inches. This value is general for normal conditions, if you enhance cover along with dia of bar you may have slightly thicker minimum criteria. Well For plain concrete footings, as per clause 22.7.4, minimum depth should be 8 inches. Further to this as per 22.4.7 if this is casted directly in contact with soil, one will have to take 2 inches reduced thickness in calculations, means one will provide 8 inches thick footing in that condition but calculations shall be based on 6 inches. I hope this would serve the purpose

To add to this, Minimum thickness above bottom of concrete reinforcement prescribed for concrete footing is: Reinforced Concrete Footing on Soil: 6 inches (Section 15.7) Reinforced Concrete Footing on Piles: 12 inches (Section 15.7) Minimum Thickness of Plain Concrete Footing on Soil: 8 inches (Section 22.7.4) Plain Concrete Footings on piles are not permitted (Section 22.7.3)