Mr. S. B. Tietz (F): I should like to deal with a few random problems that I have encountered on rehabilitation jobs. The purpose of old buildings usually changes when they are modified, and the structures have to be adapted to the new use and, sometimes, to changes of volumes. Often the building elevations are also schedules. Materials tailored to one use may not happily adapt to changing loads, spans, and the requirements of building regulations. Furthermore, materials may have deteriorated with
age or may be so hidden that deterioration is difficult to establish. Large numbers of regulations under planning, public health, or other statutory requirements, have to be complied with, or circumvented in a manner meeting the approval of enforcement officers. The problems would be less intractable if design engineers could be the arbiters of what is structurally sensible and what is structurally less sensible. More often one has to find the lowest common denominator of acceptability.