Castellated beams:- Where a number of services, water, gas, cables etc are required to pass through beams, a castellated beam may be used. The web of a standard joist section is cut along a castellated line Fig 1 The two halves are then placed one above the other as Fig 2 and welded at the connecting points. The beam thus made is one-and-a-half times the depth of the original beam from which it was cut, and so has less deflection under load.