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Concrete Cover Specifications
Required cover where standard formwork and compaction are used
Exposure Classification Required cover, mm
Characteristic Strength (f'c)
20 MPa 25 MPa 32 MPa 40 MPa ≥50 MPa
A1 20 20 20 20 20
A2 (50) 30 25 20 20
B1   (60) 40 30 25
B2     (65) 45 35
C       (70) 50
Required cover where rigid formwork and intense compaction are used
Exposure Classification Required cover, mm
Characteristic Strength (f'c)
20 MPa 25 MPa 32 MPa 40 MPa ≥50 MPa
A1 15 15 15 15 15
A2 (35) 20 15 15 15
B1   (45) 30 25 20
B2     (50) 35 25
C       (55) 40
Required cover for spun or rolled members
Exposure Classification Cover mm
A1 & A2 10
B1 15
B2 20
C 25
Source

AS/NZS Standards documentation