The upper floor is generally made of hardwood such as maple or birch, and this is laid with square edges over two or three thick nesses of paper, each layer being mopped with tar, asphalt, or similar material; or sometimes a layer of plaster is spread between the upper and under floors.
This construction may be adapted to the use of mercantile or office buildings, but the general requirements of this class of buildings will not admit of the posts occurring so often as every eight feet. This necessitates the use of a girder and intermediate beams. If these beams are spaced four or five feet apart, it will permit the use of two-inch plank which may be tongued instead of splined. With this increased spacing of the posts, it will be necessary to use iron or steer posts for a building four or more stories in height; and if the posts are more than fourteen feet apart, it will be cheaper and better to use steel beams for girders. In this case. all weight-bearing metal must be protected by at least an inch of plaster or other fireproof material.
Partitions. Where slow burning or mill construction is used for the floors of a building, the partitions should be made of solid plank plastered on both sides on metal lathing, or else of light steel framing with metal lath, and plaster.
Roofs. The same methods of framing may be employed for the roofs as for the floors, but lighter limbers can be Wised, set to the required pitch, with a. tar and gravel or metal roof. steep pitched roofs may also be constructed in the same way, trussing the timbers if the span requires it.
Supervision. The supervision of the framing of floors of brick buildings will call for constant vigilance on the part of the superintendent, as it is not only necessary to follow closely the work of the carpenters, but the fact that the mason-work is being carried along at the sane time, by a different set of workmen, will necessitate a great deal of forethought in order to bring the different parts together at the proper time.
The anchoring of floors properly, and at the proper time, will require constant attention, and the setting of plates, the building in of bolts and hangers, and the leveling-up of floors and walls to their relative positions, will require harmonious action between the mason and the carpenter.
In heavy framing, careful watching will he necessary, to see that proper connections are made between post, girders and floor beams, and that all necessary ties, straps and bolts are set and tightened.
if trusses occur, they should be strained up tightly when built and kept tightly strained as long as there are any workmen remain ing at the building, as the shrinkage of the timbers will often loosen the joints and allow sagging to occur.
Flooring. As soon as the floor timbers are in place, it is gen erally the custom to lay down a rough floor. This makes a platform upon which subsequent operations are carried 011 and also forms the foundation for the upper or finished floor. The character of this rough lining floor will depend upon the nature of the floor con struction. If the floors are of slow-burning or mill construction with the beams far apart, plank must be used of varying thickness according to the spacing of the beams. For a spacing of four or five feet, 2-inch plank may be used, but from five to eight feet of space will require 3-inch plank. This planking should be matched or splined and securely nailed to every bearing, and it will add to the rigidity of the building if laid diagonally, besides giving an even surface upon which to lay the finished floor. For the under floors of dwellings or other buildings of ordinary light construction, an under floor of ;-inch hemlock or pine is generally used without matching. The boards should be mill-planed to an even thickness and as narrow as can be readily obtained. The under flooring should be securely nailed to every bearing, and should be laid close to the exterior walls, covering the floor surface completely with no large holes or wide crevices.
Upper Floors. The laying of upper floors should be delayed until the finish of the rooms has been completed, up to the hanging of the doors. For floors that are to be carpeted, spruce or pine is generally used, and this may be laid without matching. For floors not carpeted, hardwood flooring should be used, and the boards should_ be sawed into narrow widths and matched and blind nailed.