What is the minimum clear cover for bars exposed to exterior?

• A. 1 inch
• B. 2 inches
• C. 3 inches
• D. 4 inches

Answer: (B)

Reinforcement in exterior exposure must have adequate concrete cover to protect against moisture and chloride ingress. The minimum clear cover serves as the first line of defense to slow down corrosion and maintain durability when the steel is subjected to weather, deicing salts, and freeze–thaw cycles. For bars exposed to the exterior, two inches of clear cover is the standard minimum. A smaller cover would leave the reinforcement more vulnerable to corrosion over time, while thicker covers (three or four inches) aren’t necessary as the minimum and add unnecessary bulk and cost. So, two inches is the best choice to balance protection and constructability.