This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
A word might be appropriately inserted at this point in regard to floors of piazzas and porches. These may be supported either on brick piers or on wood posts, but preferably on piers, as these are much more durable than posts. If piers are used, a sill, usually 4X6 inches in size, should be laid on the piers all around, and light girders should be inserted between the piers and the wall of the house, in order to divide the floor area into two or three panels. The joists may then be framed parallel to the walls of the house, and the floor boards laid at right angles to these walls. The whole frame should be so constructed that it will pitch outward, away from the house at the rate of 1 inch in 5 or 6 feet, thus bringing the outside edge lower than the inside edge and giving an opportunity for the water to drain off.
Fig. 160. Cross Bridging between Joists.
Fig. 161. Construction of Unsupported Corner.
The stairs are built on frames called "stringers" or "carriages," which may be considered as a part of the floor framing. They consist of pieces of plank 2 to 3 inches thick and 12 or more inches wide, which are cut to form the steps of the stairs and which are then set up in place. There are usually three of these stringers under each flight of stairs, one at each side and a third in the center, and they are fastened at the bottom to the floor and at the top to the joists which form the stair well. This subject is taken up more fully under "Stair Building."
An interesting place in a floor framing plan is where we have a corner without any support beneath it, as at the corner A in Fig. 161. This corner must be supported from the three points B, C, and D, and the figure shows how this is accomplished. A piece of timber E is placed across from B to C, and another piece starts from D and rests on the piece B C, projecting beyond it to the corner A. This furnishes a sufficiently strong support for the corner.