Clear Cover
Also known as: concrete cover, nominal cover
Clear cover is the distance between the outermost reinforcement and the nearest concrete surface.
Clear cover protects the steel reinforcement from corrosion, fire, and moisture, and ensures the bars bond properly with the surrounding concrete. It is measured from the surface of the concrete to the outer face of the nearest bar (often the stirrup).
IS 456 specifies minimum cover by member type and exposure condition — typically around 25 mm for beams, 40 mm for columns, and more in aggressive environments. Too little cover risks early corrosion; too much wastes the effective depth of the section.
Cover also affects bar-bending calculations: the cutting length of a stirrup is based on the cover-offset centreline of the member.