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Code limits on deflections On 17 November last year, Dr J. B. Bellamy invited information concerning the origin of the deflection limits set out in the various structural Codes. He responds to comments that have appeared in Verulam from Roger Mead and Mr C. K. Lim: I would like to thank Mr Lim (20 April) for his quotation from Structural engineering by White, Gergely & Sexsmith which justifies the limit as a device to prevent tension craclung of plaster. Mr Lim does not give the date the book was published, but the reference to plaster rather than plasterboard suggests a date prior to World War 2, and that could explain the thinking behind the wording of current British Codes. More recent thinking would surely consider it more appropriate to control the tensile stresses in the plaster, not the deflection of that member. On that basis, the deflection clauses in many Codes are now archaic and need overhaul. Verulam