FACTORY CONSTRUCTION AND PLANNING. The selection of the site and the design of factory buildings are vital economic factors in manufacture, as they contribute seriously to the cost of production, not only on account of the initial outlay of capital required, but because of their influence on efficient pro duction. The elimination of waste, whether of material, time or ef fort, is the chief feature of all manufacturing, and the design of factory buildings plays its part in this elimination.
The haphazard methods of erecting factory buildings are pass ing, and more systematic consideration is being given to their planning and erection, though even at the present time more ef fort is devoted to providing good machinery than good, suitable buildings. The factors most largely influencing the design of fac tory buildings are large scale and standardized production; factory legislation, both government and local; building by-laws; insur ance conditions and the welfare of the employees.
Regarding the actual design and building of factories, the de termining factor is naturally the character of the product, but certain general considerations apply whatever the product. The architect of every new factory should make himself thoroughly familiar with the processes and products of the factory before attempting his design, which should be made with a view to meet ing adequately the future needs of the industry which, under fa vourable conditions, will naturally expand, especially as the pres ent-day tendency is towards amalgamations and the formation of large corporations. One of the best ways of providing for this contingency is to design all buildings on the principle of suitable standardized units which can be increased as necessity arises. These standardized units should represent a complete organiza tion, but should be so arranged as to make future extensions pos sible without interfering with the existing business.
The supplies of electricity, gas and water are all important con siderations, especially where, as in the case of some industries, enormous quantities of any one are needed, as, for example, in the pulp and paper industry, which requires a vast amount of water; or where the cost of power represents a large part of the ultimate cost of the product. The climate is an important factor in certain industries, as, for example, in the textile industry, where a humid atmosphere is necessary ; though in this case it is be coming less important than formerly because the humidity can be controlled artificially.
Suitable Labour Supply.—Where the necessary labour supply is of the unskilled type this is not an important factor, but where skilled labour is essential it is necessary to locate the industry in a district where training and heredity have developed the required type. Skilled labour is not so migratory as unskilled on account of social and family attachments, etc.
Room for Expansion.—It would, of course, be futile to place a factory in a crowded and congested area where there is no space for expansion. The present tendency is for factories to be built on the outskirts of existing industrial areas because here (pro viding transport facilities are satisfactory, which is not always the case) land is usually cheaper, taxation lower and working condi tions better than in the towns. It is, however, difficult to induce labour that is accustomed to town life to migrate to country dis tricts and this, coupled with the housing question (see HOUSING), may be an important factor operating against an otherwise ideal site. Further, some industries may be dangerous or offensive and these must be located well away from congested areas.
Other Factors.—Capital available for investment, laws affecting the tenancy of land, sewage, floods, drinking water supply, etc., are all important points to consider in the selection of a site.
Main Types.—There are, in general, three main types of fac tory building:— I. The single story building of the weaving-shed type, having a saw-toothed roof consisting of a series of unequally inclined ridges, glazed usually only on the north side, which permits of uniform lighting without shadows. In the single story type when the site does not permit of north lighting, the ridges, which must be equally inclined, can be glazed on both sides. This type is not well adapted for overhead shafting, cranes, etc.
2. The one-story building with large truss spans, provided with accommodation for travelling cranes, etc. This is the foundry, forge and machine shop type and is suitable for medium and heavy work.
3. Multi-story buildings for all kinds of manufacture and stor age, except in the case of the heaviest industries.
Naturally, each type has its advantages and disadvantages and must be considered in relation to the product of the factory; but generally, when cost of land is not prohibitive and the product is bulky, the natural choice would be towards a one-story building. Each of these three types of building permits of a construction of any one of the following kinds:— (a) Timber and masonry, known as "Mill construction." (b) Steel framework.
(c) Reinforced concrete.
Whatever type of construction is employed, the predominating necessity is "fireproofness." In the event of a fire, although the actual amount of material damage is recoverable by insurance, the loss through disorganization is not recoverable, and frequently is so overwhelming as to prevent ultimate reorganization.
Mill Construction.—Mill construction is of various types, but in the main, the outside walls are of masonry, the floors of wood, and the roofs, posts, joists and girders of wood or metal. Where much timber is involved the great disadvantage of this type, which for other than heavy work is in other respects satisfactory, is that for fire-resisting purposes it cannot be recommended. This type of building is seldom used for heights of more than six floors on account of its lack of lateral stability, which is chiefly dependent on the masonry of the walls, and which, if developed to any height, would require to be supported by excessive-sized pillars and increased thickness in the lower stories. The adoption of this type of building is getting less and less.
Steel Framework.—Buildings of this type were made possible by the introduction of the Bessemer process of steel manufacture. Here rolled steel structural members are used and filled in with walls, floor and roof, etc. The steel members are riveted or bolted together. Where long spans without support are necessary, steel framework is essential, and it is also necessary in the case of high walls exposed to wind pressure and to the lateral forces of moving cranes. Steel framework buildings are not fireproof be cause exposed steelwork twists and buckles when subject to in tense heat, thus wrecking the building more quickly than the fire itself. If the structural steel framework is encased in fire-re sisting material such as concrete, it is admirably suitable for the interior of a factory (see FERRO-CONCRETE).
Reinforced Concrete.—Buildings of this material have come to be recognized as one of the standard types for industry. The ma terial is classed as "fireproof" and will stand the destructive ef fects of fire as well as any material. It is not usually damaged beyond repair by fire, and seldom, if ever, destroyed. It is a par ticularly durable material, and its durability improves with age. It is particularly well suited for multi-story buildings containing vibrating machinery or machines with heavy reciprocating parts. "Daylight factories" giving the maximum of natural lighting have come into vogue with reinforced concrete because columns or pillars may be more slender and the steel framework windows which are used give an increased lighting area. In cases where the floor load is higher than aoo lb. per sq.f t., reinforced concrete buildings are cheaper than those of mill construction.
Reinforced concrete buildings have developed almost entirely since 191o. The first line of development was along the form of beam and girder construction, but now the flat slab method of flooring is used, especially in cases where the live load is 15o lb. or more per square foot. For lighter loads, the development has been towards the long span joist construction with a filler of metal, tile, terra-cotta or gypsum block, which reduces dead load and saves concrete.
Floors.—These should be designed to provide facilities for fu ture changes, especially if they are of reinforced concrete, and ducts should be arranged to accommodate pipes, etc. Conduits should be properly placed and openings provided for belts, shaft ing and other accessories, properly protected. Where apparatus must be taken through floors, ample openings and trap doors or removable floor slabs are essential. Floors formed of concrete and merely spade-finished are unsuitable, and their durability should be increased by some form of floor-hardener or by the application of paving. Pavings are of many kinds, metallic, granolithic, ce mented, of fir boarding laid on battens, pitchpine boarding, brick ing, maple boarding, rock asphalt, wood blocks, etc. Each of these types has its advantages and disadvantages, some being unsuitable on account of dust, others on account of the discomfort to workers, and every building requires separate consideration. Floor areas must be laid out so as to avoid the conflict of travel in opposite directions and to permit of easy transport.
Lighting.—Windows, while no more expensive in initial outlay than walls, are an expensive item in upkeep, and with a large area of glazing the size of glass forming a unit should be of the order of 'ft. 4in. by aft. or even larger, if of the roughcast or "pris matic" type. It is not usually essential that all parts should be made to open. Steel sashing, although difficult to clean and a source of lost heat, is preferable to wooden sashing as it provides increased lighting facilities, giving 8o% to 9o% light area as against 50% to 70% for wooden sashes and frames. One-story saw-toothed buildings should have roof windows facing north to avoid direct sunlight.
Walls. The thickness of building walls is dictated by building acts and by-laws, and in most countries there is no possibility of erecting such walls of less thickness than 9in. or i4in. depending on the height and length of the wall and whether steel framework is used. As already stated in connection with the various types of building construction, various materials are used for walls such as brick, concrete, stone, etc. Where hoists and cranes are fitted these must be provided with ample support.
Roofs.—Roofs are one of the large items in building construc tion. Their particular form is dependent upon the intended pur pose of the building ; a high pitched gabled roof is the best for forges, foundries and other shops engaged in hot processes in which large quantities of heat require to be dissipated, and in other cases where a level ceiling is not required ; the glazed saw toothed form of roof provides the best condition of steady, uni form, natural lighting; the flat roof is the natural type for build ings with interior columns. Whatever the type the essential fea tures are water- and fire-proofness. For general purposes the best material is mineral rock asphalt, which is unaffected by heat or cold and requires no yearly treatment, and is also capable of withstanding traffic without damage. Where sloping roofs are used, steel or reinforced concrete roof principals are employed, and this method of support is now as cheap as steel. Slates as a cov ering are high in first cost and heavy for long span roofs, but if of good quality are very durable. Bituminous felts and other corn positions in sheet form are low in first cost, but require special treatment every few years.
Heating and Ventilation.—Of these two subjects the latter is the more important. In an ordinary factory the air should be changed three to five times per hour, while under some circum stances it should be changed as many as 20 times per hour. The temperature also varies with the nature of the work carried on, but a good average is 57° F, though for heavy manual labour a lower temperature should prevail, and for sedentary work, a higher. Various systems of ventilation and heating are employed, but the most suitable for the particular case must be selected, care being taken to economize space and avoid interference with cranes, conveyors, etc. (see PUBLIC HEALTH).
Stairways, Lifts, Elevators, etc.—Stairways should be ample for emergencies and give passengers the least inconvenience, a 63in. rise being considered good practice. Lifts should be encased with brick walls to prevent the spread of fire, and the openings should be fitted with doors of fire-resisting material made to close auto matically in case of fire.
Power Supplies.—Where power is generated on the site, the plant should be located at a point most convenient for the hand ling of fuel and ashes, and all boiler and engine-room equipment should be capable of extension. Where live steam is used in the manufacturing processes, the power plant should be situated cen trally in order to avoid the necessity of long lengths of piping and excessive loss of heat.
Fire Protection.—The installation of apparatus to deal with outbreaks of fire is a necessity in all industrial buildings. The most usual form is by the sprinkler system in which pipes are fixed horizontally along the ceiling, and supplied with water which is not released until the temperature in the building is sufficiently high to melt the solder which holds the automatic valve of the sprinklers in position. When this is released the water is dis charged over the affected area. Where sprinklers are not used, hy drants with lengths of hose should be fixed near stairs and in easily accessible positions and fire buckets and chemical fire ex tinguishers should be placed within the reach of anyone in the building. In the case of some trades, buckets of sand are more useful than water. Lightning-conductors should be fixed to all buildings. (See also INDUSTRIAL ARCHITECTURE.)