In order carry out the scheme design of slim floor beams with p.c. concrete slabs various Design Tables have been prepared and examples are presented in Tables 2a. and b. for grade 50 steel (355N/mnr yield strength) in Type 1 (non-composite) and Type 3 (composite) slabs. It can be seen that composite construction is only economic for relatively long span beams with heavy imposed loads. These tables assume that the p.c. units are placed on the beams in such a way as to cause the most onerous case for torsion during construction. Symmetric placing of the units or propping during construction will reduce torsion, potentially leading to the use of a lighter steel section, if torsion is critical to the design. A diskette offering generalised design of Slim Floors has been prepared.