GENERAL BUILDING CONSTRUCTION The primary consideration in any design is that the finished structure shall serve, in the most adequate manner, the purpose for which it is built. This will determine to a large extent the location of the columns, the general framing and type of the floor construction, depth of gir ders, size of columns, etc. The design of a ware house built to carry heavy loadings will vary, accordingly, from that of a residence. In the former, girders and beams placed close together might be used to advantage; in the latter, the ap pearance of unsightly beams in the ceiling of a room may be considered faulty design. Simi larly in a factory the layout of the girders may be planned so as to accord with shafting for machinery.
A bridge is similar in this respect, as its pur pose, location, and amount of waterway will pre determine to a large extent its design. The en gineer or architect will find, however, that rein forced concrete, owing to its plasticity, lends itself admirably to every possible requirement and condition.
A manufacturer about to build a factory or warehouse must choose between several types of construction. In this selection the govern ing considerations are cost, safety, durability, and fire protection, while many minor factors enter into each individual case.
Types of buildings for mills, factories, and warehouses may be classified as follows: (1) Frame construction; (2) Steel construction; (3) Mill or Slow Burning construction; (4) Reinforced concrete construction.
The first and cheapest type—frame construc tion—may be neglected as unsuitable for per manent installation, because of its lack of dura bility and its fire risk. Board walls, narrow floor-joists, board floors and roofs, not only do not protect against fire, but in themselves afford fuel even when the contents of a factory are not combustible.
Steel construction with concrete or tile floors, provided the steel is itself protected from fire by concrete or tile, is efficient and durable; but its first cost alone will usually prohibit its use for the ordinary factory building.
Mill construction—or slow burning construc tion, as it is sometimes called to distinguish it from fireproof construction—consists of brick, stone, or concrete walls, with wooden columns, timber floor-beams, and thick plank floors, which, although not fireproof, are all so heavy as to retard the progress of a fire and thus afford a measure of protection.
Reinforced concrete, through the reduction in price of first-class Portland cement and the greater perfection of the principles of design, has lately become a formidable competitor to both steel and slow burning construction—a competitor of steel, not only for factories and warehouses, but also for office buildings, hotels and apartment houses, because of its lower cost, shorter time of construction, and freedom from vibration; a competitor of slow burning con struction because of its greater fire protection, lower insurance rates, durability, freedom from repairs and renewals, and even, in many cases, its lower actual cost. Another condition favor able to the increase of concrete buildings is the increasing scarcity of yellow pine from the Southern States. The price of all lumber has increased so much in recent years that the cost of a first-class mill-constructed building is almost as high as the cost of a concrete structure. Com parative bids recently taken in some instances show only a difference of 5 per cent greater cost for the concrete over mill construction, and in other cases 10 per cent; so it is probable that the average difference in cost for a first-Cass mercantile building is somewhere between 5 and 10 per cent.
Considered from a hygienic point of view, reinforced concrete offers the advantage of absence of porosity, which is inseparable from the present ordinary modes of building. It does not afford shelter to rodents (rats, mice, etc.); they cannot attack reinforced concrete. This property is greatly appreciated in flour mills, grain warehouses, etc.
Reinforced concrete can also be easily and thoroughly cleaned—a property of great value in hospitals, schools, barracks, etc. Jail cells and banking vaults have been constructed from reinforced concrete, and even bullet-proof screens for target practice. It may be noted here that several great powers are now using re inforced concrete for the protection of fortresses against shell.