Q: How much cover is needed over reinforcing steel in cast-in-place concrete under ordinary circumstances ?

The 1971 ACI Building Code requires the following minimum amounts of cover, in inches:

Cast against and permanently exposed to earth: 3"

  #6 - #18 bars #5 Bars, 5/8-inch wire and smaller
Exposed to earth or weather 2 1-1/2

  Slabs, walls, joists: Beams, girders and columns: Shells and folded plate members:
Not exposed to weather or contact with the ground #14 and #18 bars #11 and smaller Principal reinforcement, ties, stirrups or spirals #6 bars and larger #5 bars, 5/8-inch wire and smaller
1-1/2 1-1/2 1-1/2 3/4 1/2

For bar bundles the minimum cover must equal the equivalent diameter of the bundle but it need not be more than two inches or the tabulated minimum, whichever is greater.

Editor's note:Regulations may have changed since this article was first published. Make sure you have the current ACI standards.