PLANT OPERATIONS – TYPES OF BUILDINGS
Industrial buildings may be grouped under four types:
1. Single-storey buildings
2. High-bay and monitor types.
3. Multi-storey buildings,
4. Special types
The decision on choosing a suitable type for a particular firm depends on the manufacturing process, the area of land and the cost of construction. However, for a factory, more than one type of building may be constructed for example, single storey plants housing production facilities and multi-storey structures for administrative purposes.
Most of the industrial buildings which are now designed and constructed are with single storey particularly where acres of land are available at reasonable rates. Extensive transport facilitates have encouraged the growth of this trend because of the ease with which men and materials are transported to the plant, wherever it is located. Industrialists now go in search of villages or suburban sites where land is cheaply available in plenty with minimum requisite infrastructure facilities. This is in sharp contrast to the earlier times when the industrialists had difficulty in acquiring an adequate area of land which can be developed for plant operations. Its high cost has forced these industrialists to build multi-storey structures. It may be noted that single-storey buildings are rarely with single storey because of construction of cellars, where the terrain of the site is uneven and the construction of mezzanine floors.
Single-storey buildings offer several operating advantages. Some of these are:
1. There is a greater flexibility in layout and production routing;
2. Truss construction ensures uninterrupted operating space. Spans of over 100ft.between columns are possible;
3. The maintenance cost resulting from the vibration of machinery is reduced considerably because of the housing of the machinery on the ground floor.
4. Space is not wasted on elevators, shafts, stairways and other service facilities which are essential in multi-storey buildings.
5. The expenditure on the running and maintenance of elevators and stairways is eliminated;
6. Expansion is easily ensured by the removal of walls;
7. The cost of transportation of materials is reduced because of the absence of materials handling equipment between floors;
8. All the equipment is on the same level, making for an easier and more effective layout supervision and control;
9. Greater floor load-bearing capacity for heavy equipment is ensured.
10. The danger of fire hazards is reduced because of the lateral spread of the building;
11. Single-storey buildings offer economy both in terms of the time required for their construction and the overall cost per sq. ft.
12. They have an elegant appearance.
Single-storey buildings suffer from some limitations. These are:
1. High cost of land, particularly in the city;
2. High cost of heating, ventilating and cleaning of windows;
3. High cost of transportation for moving men and materials to the factory which is generally located far from the city.
A single-storey construction is preferable when:
1. Materials handling is difficult because the product is big or heavy;
2. Land is not a problem and its cost is not a worry;
3. Natural lighting is desired;
4. Heavy floor loads are required;
5. The construction has to be completed within a short time; and
6. Frequent changes in layout are anticipated.
High Bay and Monitor Type
This is a single-storey structure with this difference, that the roof truss is surrounded by a monitor. The building is designed to give maximum overhead space for a given floor area. The overhead space may be used to operate a crane and other overhead facilities. The monitor offers good natural ventilating, and the side walls are built with glass, act as windows for natural lighting. Buildings for steel mills and foundries are often of the monitor or bay type; they enable the management to take advantage of natural ventilation and illumination coming from high roofs and center openings, which provide ample room from crane operations.
Multi-storey buildings are gradually becoming an exception for industrial purposes, because the trend now is for the construction of single-storey structures, except in Hong Kong and Singapore, which are water locked. However, for hotels, schools, colleges, shopping, complexes and residence, multi-storey structures are generally popular, particularly in cities. When constructed for industrial use, multi-storey buildings offer the following advantages:
1. Maximum operating floor space per sq. ft. of land; this is best sited in areas where land is very costly;
2. Lower cost of heating and ventilation;
3. Reduced cost of materials handling because the advantage of the gravity flow of materials can be availed of;
4. In case of an assembled product, the operations on the different parts can be so planned that the work moves in the same general direction to the assembly floor, with minimum movement between floors;
5. Use of overhead storage;
6. Well-adapted to light manufacturing industries.
There are also certain disadvantages with multi-storey buildings which make them less popular than single-storey structures. These disadvantages are:
1. Materials handling becomes very complicated. A lot of time is wasted in moving them between floors;
2. A lot of floor space is wasted on elevators, stairways and fire escapes;
3. Floor load-bearing capacity is limited, unless special construction is used, which is very expensive;
4. Natural lighting is poor I the center of the shop, particularly when the width of the building is somewhat great;
5. Up to a certain stage, say, up to four storey, the cost per sq. ft. of floor area may be the lowest; but beyond that stage, the cost of construction rises rapidly;
6. Layout changes cannot be effected easily and quickly;
7. There is difficulty in supervision.
8. Tall building may not be good-looking.
Multi-storey buildings can still be justified:
1. In the manufacture of light products, using light materials;
2. When materials can be handled by gravity feed;
3. When the acquisition of land becomes difficult and expensive;
4. When the floor load is less.
5. Process calls for feeding inputs from a certain height while getting processed at each floor.
Generally speaking, textile mills, food industries, detergent plants and chemical industries use these types of buildings.
Some manufacturing processes require a particular type of building. The aircraft industry, for example, requires building with wide spans, which may range from a width of 300ft to 400ft. The building for a saw mill is constructed without side walls so that the flow of wind may be steady and saw dust does not accumulate inside the plant. Allowing the dust to accumulate inside the building is like welcoming a fire at the doorstep because saw dust catches fire very quickly and easily. These buildings are constructed for a specific purpose and are, therefore inflexible. Obsolescence in this type is high because of rapid changes in technology.