A practical form of construction. Should not be over four stories. Two stories preferable for a machine shop. Foundation walls. Supporting posts. Strengthening knees. Lengths of bays. Side walls. Vertical planking. Steel shingles. Cold water paints. Ground floor timbers. Floor planks. Air spaces. Floor laid directly on coal-tar concrete. Three methods of floor construction. Improved form. Another plan. Second-floor construction. Roof construction. Roof planking. Truss bracing the framework. Strength of this form of construction.

It is entirely feasible to construct a practical form of machine shop or factory building entirely of wood, and on account of the relative cheapness of the materials it will be necessarily more economical to do so than to build it of brick and wood combined.

It is not usual, however, to build in this form over four stories in height, and it is perhaps better to confine the height to two stories, when it is to be used as a machine shop, or for manufacturing when machinery is to be used, unless it is of a light variety.

Fig. 14 is an isometrical perspective of this form of construction, shown of two stories.

Foundation walls are built on all four sides, the same as if brick walls are to be erected. Piers are built to support the central posts, and all posts and sills rest upon cast iron plates bedded in cement mortar on the walls and piers.

All posts extend from the walls or piers to the rafters. The floor timbers of the second floor rest upon wooden knees bolted to the posts. If preferred, these knees may be made of cast iron, but the difference in the cost of the two will not be great, and there will be the liability of the cast iron to crack under very heavy and sudden strains unless carefully designed for the purpose. In case they are used, all component parts or members, such as the resting plates, strengthening ribs, etc., should be of nearly equal thickness, in order to prevent undue strain on the metal in cooling after they are cast. Ribs, say three quarters of an inch to one inch square, according to size of the timber to be supported, may be formed on them and these let into grooves cut in the timbers, which will materially assist the bolts in holding them in proper position, and in resisting strains.

Factory Building of Slow Burning Construction, of Wood only.

Fig. 14. Factory Building of Slow-Burning Construction, of Wood only.

The bays of this form of building are built about 8 feet centers, and the transverse span of the floor timbers should be about 20 feet, never to exceed 25 feet.

The sides of the building may be of 2i-inch, or 3-inch planks, planed on the inside, tongued and grooved, or better, with a groove in each edge and separate splines put in, and spiked on horizontally, the window frames sustaining the ends of the planks reaching them. The planks should be at least two bays (16 feet) in length, and nominally break joints every three feet. As the spaces above and below the windows are the only places where the planking is horizontally continuous, it will be better to break joints every two planks.

If preferred, the planks may be put on vertically, for which purpose horizontal spiking strips may be let into the posts, or spiked on their surface, at the tops and bottoms of the windows.

A very strong and rigid structure may be constructed by applying the planks in a diagonal position, thus bracing the framework in a most effectual manner. The waste of materials will be somewhat increased, and the labor cost will be considerably higher.

Outside of this planking may be applied corrugated iron, sheet steel shingles (so-called), or sheet steel stamped to represent clapboards or stone work. A large variety of this material is now made in artistic forms, which is easily applied, attractive in appearance, very durable when kept painted, and nearly impassable to any ordinary fire.

The timber work showing inside, as well as the under side of the second -floor planks, and the roof planks, should be planed and may then be kalso-mined or covered with any of the so-called "cold water paints," which may be of any desired tint, neat appearance, and sufficiently porous to permit the timber to season nearly as well as if it were not covered at all.

The ground floor may be laid upon floor timbers, as shown at the right of the engraving, and should consist of 3-inch planks, about 6 inches wide, grooved on each edge, and have separate splines fitted in. They should be two bays (16 feet) in length, and break joints every three feet. Upon these should be laid a top flooring of 1¬-inch hard wood, running the same direction as the 3-inch planks. These planks may be taken up and replaced at any time when they become worn and unfit for further use, without disturbing the main flooring.

To preserve this floor from decay, an air space, at least the thickness of the floor timbers, and twice that is better, should be left under it and be ventilated by small grated openings in the foundation walls.

At the left of the engraving is shown a floor laid directly upon coal-tar concrete. There are three methods of putting down this kind of a floor. The first style is to lay down a foundation or bed of small crushed stone or cinders to the depth of six inches, for ordinary purposes. Upon this is laid two inches of coal-tar concrete, or of sand mixed with hot coal-tar, and directly upon this is laid 3-inch planks, not tongued or grooved, and over them, and at right angles to them, a top floor of 1¬-inch hard wood planks. These being spiked together form a solid and rigid mass supported by the concrete.

This form may be much improved upon by laying 3×4 inch sleepers, which have previously been mopped with hot tar, on the crushed stone, or cinder bed, leveling them up and then filling in the spaces flush with the top of the sleepers with hot tar concrete, then spiking down a main floor of 2-inch planks, not matched, and over this, at right angles to it, nailing down a top floor of 1¬-inch hard wood planks.

Still another plan is to lay down the crushed stone or cinders as before, drive stakes four feet apart each way, the tops level with what is to be the under side of the floor. To these spike nailing strips, say of 2 x 4 inch scantling, set edgewise, previously tarred on the bottom, and fill up the spaces with coal-tar concrete as before, and spike down 2-inch planks. This makes a cheap floor and is sufficiently solid and durable for many cases. If it is to be subjected to hard usage, it will be advisable to cover it with a top floor which can be readily renewed when worn out.

The second floor is built like that in the preceding chapter, that is, 3-inch grooved planks, with separate splines, two thicknesses of rosin-sized paper, mopped with hot tar, and a top floor of hard wood 1¬ inches thick. The 3-inch planks are at least two bays (16 feet) in length and break joints every three feet.

The roof is built with the rafters supported on the side and center posts, fastened at the center with ¾-inch iron dogs and bolted to the side posts and to the knees of the center posts. The rafters have a pitch of one half inch per foot, and are covered with 3-inch planks, grooved on both edges, joined by separate splines, two bays (16 feet) in length and breaking joints every three feet. The roof planks may be covered with roofing paper mopped with tar, and over this thick roofing tin, or with two or three thicknesses of roofing felt, and then tar and gravel, in the usual manner.

If it is desirable to erect a frame that shall be entirely self-sustaining, before any planking is put on, it can be done by letting into the outer posts spiking strips in a diagonal position, forming truss-like braces. These will be under the windows on the first floor, and between the first and second-floor windows. In this manner the frame may be rendered very rigid.

While this construction is simple and apparently not heavy, such a building will sustain great weights in proportion to the amount of materials used in their construction, and will successfully withstand shocks, strains, and vibration that would seriously injure structures of seemingly much greater strength.