The kind of superstructure best to be adopted for the barn depends on many conditions. The balloon construction may be used for small barns, but large ones naturally require large timbers or many small ones, hence the old style of frame-work, with some modification, is usually adopted. In modern barn buildings the main timbers are reduced in size, more and lighter braces are used in lieu of the large mortised and pinned braces. They are cut with smooth, angled ends and spiked to posts and beams. A brace of 2 × 4 inches is inexpensive, and allows of following the old rule of placing a brace in every angle made by the principal timbers.

Another modification should be adopted: the joists, so far as possible, should rest on sills and beams and not be gained into them. It is unwise and unscientific to cut gains for the reception of the ends of the joists at considerable expense, since such gains weaken both joists and sills. In most cases the joists may be placed on top of the sills, thereby obviating the necessity of framing, while preserving the strength of sill and joist entire. When it is desirable, as it often is in small structures, to have the top of the sill or beam coincide with the tops of the joists, it is cheaper and better to use a rather light timber and fortify it by nailing upon it 2 × 4-inch studding (Fig. 109), thereby avoiding the necessity of cutting gains, while giving additional strength to the timber which supports the joists.

The joists in barns should be bridged as in houses. That part of the barn floor which is above the root-cellar should be deafened, as shown in Fig. 101. Cleats nailed on the sides of the joists serve to support the short boards which carry the deafening material. The 2-inch space between the false and the true floor is filled with mortar composed of about five or six parts of sand to one of lime or cement. If all of the floor driven upon above the basement is deafened, it will deaden sound and promote warmth in the lower story.

While the balloon frame has been almost universally adopted in the construction of houses, it is only recently that large barn frames have been successfully constructed on the same general principles. The plank frame has now been so modified and improved that it serves well for the largest farm building. All of the frame timbers are sawed two inches thick and of variable widths, as required. Instead of uniting the timbers by means of mortise and tenon, they are fastened with wire spikes. This new method secures as strong a frame as the old, and saves from 30 to 40 per cent of material, while the plank frame is more easily and cheaply erected than the large timbered frame is. The 2-inch frame material can be so placed as to direction and position that it will secure the maximum of strength with the minimum of lumber.

The illustration (Fig. 110) shows one end of a 67 × 97-ft. barn, posts 18 ft. long, recently erected at the Pennsylvania Agricultural College. A cross-section at one side of the driving floor is also shown (Fig. 111). A cross-section of a built-up post is seen in Fig. 112. It will be seen that the building is firmly tied together, the roof fully supported, and that no timbers obstruct the unloading of provender by horse power. This new method of constructing large frames is so little known and the principles involved are so valuable that I append a foot note at the risk of being misunderstood.[7] Since long, large timbers have become expensive, it is probable that the plank frame will become as common in the near future, in barn building, as the balloon frame is in house building.

It is frequently convenient to place horses or other animals on the second floor above other animals, or above a covered yard, in which case a tight floor may be made as follows (Fig. 113): Lay an unmatched, rough inch floor; upon this place strong, tarred building-paper, with joints well lapped. Saw and prepare the 2-inch planks which are to form the floors. For every four hundred square feet of floor, procure one barrel of hard Trinidad asphalt and three gallons of gas tar. A large iron kettle may be used for heating and mixing the material, which should be in the proportion of about one to ten. With an ax remove the barrel, and chop off and place in the kettle pieces of asphalt until it is not much more than one-half full, then add the due proportion of gas tar. The kettle should be placed in a rude arch and at a little distance from the building. By means of a slow fire heat the material. When all is ready, dip the hot mixture into a galvanized iron pail and pour it in a small stream on the paper, spreading to the width of the plank intended to be laid, by means of a shingle or paddle. Lay the plank in the hot material, being careful that when it is spiked down the hot asphalt does not fly up into the face. Then proceed to lay other planks in like manner. Finally pour some of the material into the cracks if there should be any.[8]

Should the floor become worn in time and need repairing, even up the surface by spreading thin cement mortar upon it, and upon this lay a second plank floor. The cement mortar will assist in making the floor water-tight and in preventing dry rot. Barn floors which have become much worn from driving over them may be treated in like manner. Where it seems advisable to place cows on the second floor, and over a manure cellar, the following plan may be adopted: A tight floor, as in the former case, is built with drips as shown; a small hole is placed between each pair of stalls, through which the voidings of the animals may be dropped into the story below, the floor of which is concreted. The objection might be raised that the manure underneath the animals would be objectionable; but since the floor of the stable described is tight when the openings in the drip are closed, and the story below is well lighted and ventilated, the objection does not hold good.

As far as possible, horses should stand with their heads away from the windows, as draughts of air and glaring sunlight are trying to their eyes. A few box stalls are convenient, and assist in providing the two cubic feet of air space which should be allowed for each pound of live weight in the horse barn. The stable should be so situated that the fumes of ammonia arising from it cannot reach the harness and carriages, if they are highly polished and expensive. The horse stable may often be placed on the second floor of the wing, as it brings it on a level with the main driving floor and near to where the wagons are likely to be kept. The story beneath the horses makes an acceptable covered yard. An office, which may be warmed, and a repair room should be provided in one corner of the barn or in a small detached building near to it.

If the farm is ample, and large amounts of hay and grain are to be stored, instead of building a wagon house, the main barn might be extended twenty feet, more or less, in length. This additional room may be used for carriages and light harness in part, and in part for the storage of grain, meal, and the like. The space underneath this room would serve to enlarge the cow stable. The place for washing carriages might also be located on the lower floor, where it would serve for storing the milk wagon as well, and the space above it could be devoted to storing hay and the like. Barn windows should have small panes of glass, as the cross bars of the windows serve not only to hold the glass but as fenders also. Since the glass in barn windows is likely to be broken, the cost of repairs is reduced to a minimum if the panes are small.

A cupola, if it is large and well proportioned, may add beauty to the barn and serve to ventilate the mows, thereby making them cooler for the workmen than they otherwise would be. It may also give opportunity for lighting the mows and the floors, thereby avoiding the necessity of windows at the side of the mows, where they are likely to be broken and where they are covered as soon as the barn is partly filled.

Hay and grain contain 20 to 25 per cent of moisture when stored, and hence tend to become warm. The hot, moist air, due to this heating, ascends to the roof or cupola and forms an easier passage to the earth for electrical discharges than the normal air of the building does. Thunder storms prevail largely about the time barns are filled, hence they should be provided with good lightning rods, that an easier and safer way may be provided for the discharges than by the ascending warm, moist air of the building. (See lightning rods, Chap. XX.)

Barns not more than sixty feet wide may be covered by self-supporting roofs. The curb or gambrel form is the best. If the gables are clipped, the cost will not be materially increased, while the structure will be much improved in looks. Barns should have strong, wide, projecting roofs; a few extra rows of shingles at the eaves will serve to protect the outside covering and the framework, and will improve the looks of the structure. Should it be decided to paint the barn, an ample projection will greatly reduce the expense of keeping the paint presentable. Financially speaking, it does not pay to paint the barn unless the boarding is placed horizontally. The boarding of many unpainted barns is still in a good state of preservation, although they were built more than three-fourths of a century ago, and had roofs projecting but a few inches over sides and ends. Protected by a roof projection of one to two feet, rough, vertical barn boards may last for one to two hundred years without paint. It may be said, then, that properly constructed barns are painted to improve their looks and not to preserve them. When the barns are well removed from the house and virtually hidden by trees, they may be left unpainted, but where they are conspicuous they should be painted, that the barn may not mar the beauty of the home. The oxide of iron, which usually has a red or reddish tinge, mixed with pure oil, forms a most desirable and satisfactory barn paint. (See Painting the House, Chap. IX.)