Minimum concrete cover requirements are presented below for various building codes.
Japanese Building Code
The Japanese building code provides the following guidance:
Type of Structure | Design Cover (mm) | ||
Not in Contact with Soil | Slab | Internal | 30 |
External | 40 | ||
Column / Beam / Structural Wall | Internal | 40 | |
External | 50 | ||
Non-Structural Wall | Internal | 30 | |
External | 40 | ||
Ground Floor Slab | 50 | ||
In Contact with Soil | Column / Beam / Structural Walls / Slabs | 50 | |
Foundation Slabs | 70 | ||
Foundations | 70 |
These values include a 10 mm allowance on the nominal cover to account for construction tolerance.
ACI 318
The American Concrete Institute (ACI 318-11) provides the following recommendations for minimum cover:
Type of Structure | Design Cover (mm) | ||
Permanently in Contact with the Ground | 75 | ||
In Contact with Ground or Water | No. 16 rebar and smaller | 40 | |
No. 19 to No. 57 rebar | 50 | ||
Not Exposed to Weather or in Contact with the Ground | Slabs, Walls, Joists | No. 36 rebar and smaller | 20 |
No. 43 and No. 47 rebar | 40 | ||
Beams, Columns | All rebar | 40 | |
Shells, Folded Plate Members | No. 16 rebar and smaller | 13 | |
No. 19 rebar and larger | 20 |
For other conditions, such as corrosive environments or a minimum specified fire resistance, refer to the relevant clauses in the ACI code.