It often happens, in dwellings and tenement houses, that the stairs are built as shown by the plan, Fig. 33, and it is desirable to extend the upper floor into the stair well without any vertical support at the corner A. If there is a partition or girder under the dotted lines B, and the floor joists run at right angles to it, the projecting portion can be easily supported by merely extending the floor joists the desired distance beyond the supporting partition.
Very often, however, the joists run the other way and there is no support below, so that the corner must be made self-supporting, and just how to make it so is sometimes a puzzle to the young architect or draughtsman. Probably the best method of doing it is that shown by the partial framing plan (Fig. 34).
The trimmer B and header A are first framed in the usual way, then a heavy timber (C), of about half the depth of the floor joists, is framed diagonally between A and B, with its under side flush with the joists. This forms a support, at its centre, for the cantilever D, which in turn supports the outer end of the pieces E, E. The piece D should be made the full depth of the joists and notched over the piece C. Short pieces of joist are then cut in between the timbers A, D and E, and the floor is then ready for the flooring and lathing.
There are many places where this method of framing may be employed, particularly in tower stairways. The same method could be carried out with iron framing, omitting the short pieces of joists. If the projection is very great, however, and the floor is a heavy one, it will be better to support the corner directly, either by a post or rod.