As soon as the floor timbers are in place, it is generally the custom to lay down a rough floor. This makes a platform upon which subsequent operations are carried on 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 construction. 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 7/8-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.

For floors of kitchens, offices or other places where much wear will come, and where the expense of oak or other fine woods is not desirable, floors of rift Georgia pine may well be used. Birch and maple also make a good floor and have good wearing qualities. For parlors, halls, and for parquetry flooring, oak is used to a great extent, either by itself or in connection with other fancy woods. All hardwood flooring should be quarter-sawed. The usual thickness of flooring stock is 7/8-inch, but for stores, factories, or public buildings, 1 1/8-inch or 1 1/2-inch stock should be used.

Stock

Spruce and pine floorings are carried in two grades - first and second quality. First quality is free from knots, while second quality will have small and tight knots.

Hard pine flooring is rated as rift, or "quarter-sawed," first and second clear, and star. Only rift hard pine should be used for a good floor, as "slash" boards will split and sliver. Oak flooring should always be quarter-sawed, and this as well as all hard woods should be used in narrow widths, 2 1/2 inches being as wide as should be used for first-class work. First-class flooring is usually grooved on the under side to lie close to the under floor and should be matched and blind-nailed for good work. For offices or factories, square-edged boards will wear better and admit of renewal more easily than matched flooring. Floors laid diagonally or across the under flooring will lie smoother and remain closer, than if laid the same way as the under floor. If the added stiffness is desired for mill floors, and it is not convenient to lay the floor diagonally, a degree of stiffness may be gained by laying the floor square and nailing it in diagonal rows.

Paper And Deafening

Between the upper and under floors, paper should be laid, and a deafening of plaster, quilt or mineral wood may be used. For mill or factory floors, two or three thicknesses of paper should be used, mopped with tar or asphalt.