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Detailing symbols (previous & current)

The symbols used on reinforcement drawings to indicate the type of reinforcement have been specified in various Standards over the years, as indicated below:

BS 1478:1948
Not specified: many variants for square and twisted bars.

BS 1478:1964
MR = round mild, HR = round high yield, HS = square high yield

BS 1478:1967
M = round mild steel, H = round area high yield, S = square area high yield

BS 4466:1969
R = round mild steel, Y = round area high yield

BS 4466:1981
R = Grade 250, T = Grade 460/425 type 2

BS 4466:1989
R = Grade 250 plain, T = Grade 460 type 2, S = Grade 460 stainless, W = Grade 460 plain, D = Grade 460 type 1

BS 8666: 2000
R = Grade 250 plain, T = Grade 460 type 2, S = Grade 460 stainless, W = Grade 460 plain, D = Grade 460 type 1, X = Type of reinforcement not included in the above but having properties defined in the design or contract specification.

BS 8666: 2005
H = Grade B500A, B500B or Grade B500C in accordance with BS 4449: 2005
A = Grade B500A in accordance with BS 4449: 2005
B = Grade B500B or Grade B500C in accordance with BS 4449: 2005
C = Grade B500C in accordance with BS 4449: 2005
S = Specified grade and type of ribbed stainless steel to BS 6744: 2001
X = Type of reinforcement not included in the above but having properties defined in the design or contract specification.

Further information on how reinforcement has developed over the years is given in Concrete Society Technical Report 70, Historical approaches to the design of concrete buildings and structures.

Acknowledgement: The Concrete Society

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Historic reinforcing bars and steel fabric

TR70 Historical approaches to the design of concrete buildings and structures