Cover in concrete is the least distance between the surface of embedded reinforcement (steel bar) and the outer surface of the concrete. It is provided to protect steel from corrosion, to provide thermal insulation, which protects the reinforcement bars from fire and to facilitate bond and anchorage between steel and concrete. Cover shall be made up of proportion not less than 1:1½:3 concrete.
Cover to be provided shall be as follows if not specified/shown in construction drawings.
- For RCC slab, the cover should be 15 mm or dia of reinforcement whichever is greater.
- For RCC beam, the cover should be 25 mm or dia of reinforcement whichever is greater.
- For RCC column the clear cover should be 40 mm unless other-wise specified in drawing. In case of columns of minimum dimension of 200 mm or below, whose reinforcing bars do not exceed 12 mm, minimum cover of 25 mm should be provided.
- For lintel, chajja or canopy, 15 mm or the diameter of such reinforcements, whichever is greater.
- In case of footing of columns or walls (side and bottom), the clear cover shall be 50 mm.