Warehouse Keepers at Harrogate
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BUILDING DESIGN AND CONSTRUCTION, FIRE PREVENTION, PALLETIZATION AMONG SUBJECTS IN OPENING SESSION
By S. Buckley, Assoc I nst T
AUTHORITATIVE survey of warehouse design and construction was an outstanding feature of first business session of the annual iference of the National Association Warehouse Keepers held at Harrogate Wednesday. It was made by Mr. B. Waters, art architect specializing in rehouse design.
kt the outset, Mr. Waters stressed that would be dealing with the design and istruction of buildings suitable for rehousing, rather than their use. He n outlined decisions that had to be en in settling matters of design and tstruction, and the role that a client 1st play if the architect was to serve n satisfactorily.
The client must be able to state his juirements. but clearly this was very ich easier for a man who was building quently. Where, however, building S an infrequent happening in an tanization, then the architect must Lei the client to formulate his require There were three ways in which the dgn of an industrial building could approached. he said. It could be ;cted as a standard building, in the pe that it will be suitable for the purse for which it was to be used. zondly it could be entirely "custom ilt "—suitable in every respect for its rticular requirements but for nothing e. Finally it could be built to suit the mediate requirements but in such a y that it could be adapted to chang!, needs. Only the last approach could rmally be recommended.
DOMINANT FACTORS In planning a warehouse. Mr. Waters umerated the dominating factors. lese included methods of storage (on Bets on racks or "in heaps"). methods handling (by fork-lift truck, pallet ick or by overhead conveyor) and hods of delivery and dispatch to old cross-circulation in internal and ternal movements.
When the movement within a building s been established, the movement of hides around the building must be conlered and a satisfactory pattern evolved at would permit free movement of livery and dispatch vehicles and prole adequate car parking.
In arriving at the plan shape of -a aiding several items of information !re required. These were: the types d quantities of the goods to be stored: pe of transport to be used for delivery d dispatch; access to the site: methods storage: size and height of pallet:
height of stacking; method of handling; method of assembling outgoing loads; floor at ground level or raised; loading docks; and the number of employees.
A ratio of 60 per cent storage to 40 per cent circulation was acceptable when planning pa lletization. If palletization was found to he suitable, then the maximum height should be used. The cost of increasing the height of a single-storey building was relatively small, since only the external walls and stanchions were affected. The expensive items of floor and roof were constant, and there was better land utilization.
Gangways for hand-stacking were smaller than those required for mechanical equipment. In a small warehouse the overall area of a building might be increased because of the greater risk of gangways for the trucks, and in such cases the increased height made nossible by the use of a fork-lift truck might offer no economy.
The relationship between warehouse floor and ground level must be studied, to establish that a raised loading dock (if required) could be provided economically. In considering the structure of a building, the first consideration was normally stanchion spacing.
Arguments were frequently advanced for using the maximum possible span: but this could be expensive.
It should he noted that American practice was to use a square grid of 50 ft. to 60 ft. without any apparent inconvenience. If it was necessary to use internal stanchions in a wide building, then the stanchion spaces must he related to the pallet layout if space was not to be wasted. If a travelling crane was required the roof span should be reduced as much as possible for economy in the cost of the crane.
FLOOR LOADINGS Regarding floor loadings, the combined weight of truck and loading pallets could be considerable. This offered no problem in singlc-storey buildings if the concrete floor plan was placed on a well-compacted base. The load was then distributed through the slab and base and the bearing capacity of the ground then determined the load that could he carried.
Services to be considered included mechanical and electrical installations, and water supply. These could he further sub-divided into heating, lighting and ventilation. Service installations must be considered both in relation to the goods to be stored and the personnel working within the building. The mechanical services include heating, ventilation, cooling, compressed air and sprinkler installations.
In a warehouse, only space heating was normally required and low or high pressure hot water (depending upon the size of the installation) would generally be the first choice. When doors had to remain open during working hours, an air curtain could usefully be installed.
Ventilation was seldom an important factor in warehouses, except to prevent a build-up of heat during week-ends when the premises were shut down.
SPRINKLERS In large warehouses a sprinkler installation might be required by the local fire brigade. The cost of this. could frequently be justified by reduced insurance premiums.
Commenting on electrical installation. Mr. Waters claimed that in warehouses this would normally be confined to lighting. although power might be required to operate handling equipment. Good intensity of lighting (say 20 lumens) was essential in gangways, whereas an intensity of 10 lumens was probably adequate over the stacks.
As to the envelope of the warehouse. the choice of materials for walls and roof coverings was influenced by strength. insulation value, fire grading, appearancc and cost. Insulation values were dictated primarily by the conditions of the Thermal Insulation Act; but might also be influenced by the special requirements of the building.
Fire grading had regard not only to containing a lire within the building but also to preventing the spread of fire front other buildings. Under the building regulations which come into force on February 1, 1966, the provision for fire resistance in storage buildings included a limit of 750.000 Cu. ft. in one compartment.
This meant, for example, that a build ing 25 ft. high could not have an area in excess of 30.000 sq. ft. (say 150 ft. by 200 ft.) unless it was divided into compartments. Minimum periods of fire resistance were also laid down.
Mr. Waters described the materials suitable for walls and roofs and, regarding glazing. said that associated with natural lighting was the problem of solar heat gain—in which event some form of north lighting should be adopted. Alternatively, natural lighting could be omitted altogether.
The height and width of door openings must be related to the equipment chosen. A width of aft. was usually sufficient; but if trucks had to make a right-angle turn to go through (he opening, a width of 10 ft. should be used. Salient angles should be protected. A useful average height of door was 10 ft. 6 in.; but, again, this should be checked with the selected equipment. Rubber doors could be used with advantage for door openings on trucking routes.
• Whilst finishings to be used in a warehouse should be the most appropriate that could be obtained for the money available, the floor finish was an exception. It must be the best possible to stand up to the wear imposed by trucking, even when rubber tyres or fibre wheels were used. Steel-wheeled trucks should never be used.
. A smooth floor offered less resistance to the running of a truck. so that a more compact and less costly truck might then be suitable.
Trucks in the warehouse and lorries in the yard were liable to cause damage whilst being manceuvred. Anything that was susceptible to damage should be protected.
FLOOR LEVEL Discussing the question of floor level in relation to ground level of a warehouse, Mr. Waters said that a raised loading dock would be costly to provide and it was always difficult to determine its correct height, although this could be overcome by the use of a dock leveller. If it was intended to off-load incoming goods with a fork-lift truck, a raised loading dock was unnecessary and ;he outgoing goods could be loaded with a powered conveyor.
If the building was rail connected, or if it was regularly served by vehicles of known height, the raised floor had advantages.
In constructing a cold store, the main consideration was provision of adequate insulation, especially in the floor slab. Cork was the traditional insulating material although this was tending to be superseded. Expanded rubber (Onazote) had been available for some time, and recently cellular glass insulation (Foamglas). made in Belgium, had been intro
duced in this country. It was strong, water-proof, flame-proof, acid and rotproof.
There was the danger of frost getting into the ground below a cold store and c24 of frost heave " lifting the building.
This could be prevented by ventilating the space below the floor, by cutting in a heating mat, or by doing both. Fully insulated doors must be used; but an air lock was unnecessary if an air curtain was provided to stop the ingress of warm air when the doors were opened.
Space requirements for motor vehicles would be determined by the overall size of vehicles and their manceuvrability. Such particulars appeared in lists published annually by The Commercial Motor-. In arranging the extent of the forecourts. allowance must be made for vehicles to manceuvre on one lock if speed of movement were to be maintained. When driving forward. a vehicle could not start to turn until it was clear of the one next to it.
A useful guide for the clear space required for a rigid vehicle, in front of any obstruction, was a total of 50 per cent or more in excess_ of the length of the vehicle. Less space was required for articulated vehicles. A vehicle which exceeded 12 ft. in height was unusual and, in practice, a clear, height of 13 ft. for door heads or canopies was sufficient in most cases.
British Road Services used canopies of this height for general purposes in their own depots with part of the canopy raised to a height of 15 ft. for taller vehicles; hut this was regarded as the maximum. Sufficient height must be allowed under the canopy for unsheeting a loaded vehicle.
Some economy could be made in the turning space required in front of a loading dock if a saw-toothed pattern was used. Rut although the-saw-toothed loading dock resulted in a saving of space to the front, the length on the loading dock must be increased. and might he 18 ft. per vehicle instead of the more usual 10 ft. or Il ft. for vehicles at right angles to the dock.
Assuming a warehouse of 30.000 sq. ft.. which would cost, including roads, site work and fencing (but excluding the cost of the site). around 170,000 to 00,000 exclusive of fees, the timing would be as follows:—
The preparation of drawings and applications for by-law and planning approval (excluding building licence application, for which there is as yet no procedure) would take three to five months. Preparation of bills of quantities and submission of tenders would take a further three months, whilst the actual building would last six months. This would give a throughput time, from the approval of set plans, of about 12 to 14 months.
If the throughput time was to be reduced, then it was possible to select a contractor by inviting tenders on an approximate bill of quantities prepared from the drawings used for the by-law submission, or to negotiate a contract with a selective contractor on even less information than that. The reduction of throughput time hy using these methods might result in slightly higher costs, which could be acceptable if the building was urgently required.
£ 77 m. Losses By Fire
Fire loss for 1964 was inn., and of this amount (27m. was accounted for by 130 large fires which occurred in industrial, commercial and warehouse premises. These grim facts were given by Mr. P. Murray. Senior Fire Prevention Officer, Yorkshire (West Riding) County Council. in a talk on fire prevention.
Moreover, he continued, there was a greater financial loss when fires occurred in warehouses than in many other types of premises, because the goods stored therein were finished articles and represented a substantial number of man-hours and material spent in their production.
Unfortunately, it was a peculiarity of human nature that disaster of any kind only came to someone else and, as regards fire, many considered they had done their duty when they observed the law and paid their insurance premium.
This was not the case, Mr. Murray insisted. The law was a medium for insuring safety when fire occurred and an insurance premium was a precaution against insolvency when a fire had occurred. But everyOne had an obligation to prevent fire starting.
It was an integral part of management to consider the most effective measures feir avoiding fire. These generally fall into three main categories, namely measures which were required by statutory acts or regulations, measures required by an insurance company to keep the occupancy hazard within the range of the acceptable insurance and measures that a wise management could take of their own free will to secure the safety of their premises and their employees.
Mr. Murray then went on to survey the aspect of cleanliness, fire alarm, smoking. fire-fighting equipment and compartmentation. As an example of the importance of the latter aspect, he referred to the British Railways' Bishopsgate Goods Depot which occupies 10+ m. Cu, ft. without effective separation. In this case the rapid spread of fire resulted in a loss of approximately Om. The main building was so severely damaged that the remaining structure had to be demolished,