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a case where the bridging joist rests direct on the iron binder, solid strutting being inserted between the joists to keep them vertical. The ceiling is formed of either lath and plaster or match-boarding fixed direct to the joists, the binder being cased round as shown. Fig. 339 illustrates an arrangement of casing the under side of a girder or binder when it is deeper than the joists. If constructed as shown at Fig. 340 a flat ceiling can be obtained under the binder; but this construction cannot be adopted when the iron member has to serve as a girder for floors having heavy loads to carry, as a single binder would not be deep enough.

The plan of a framed floor, 45 ft. by 26 ft., is shown at Fig. 341. Three girders, supported at their centres by iron columns, carry the binders as shown. The sizes of the various members are: Girders, 14 in. by 10 in. sawn, reversed, and bolted with a ¾-in. rolled flitch in the centre; binders,