A warehouse is a building for storing goods. Warehouses are used by manufacturers, importers, exporters, wholesalers, transport businesses, customs, etc. They are usually large plain buildings in industrial parks on the outskirts of cities, towns or villages.
They usually have loading docks to load and unload goods from trucks. Sometimes warehouses are designed for the loading and unloading of goods directly from railways, airports, or seaports. They often have cranes and forklifts for moving goods, which are usually placed on ISO standard pallets loaded into pallet racks. Stored goods can include any raw materials, packing materials, spare parts, components, or finished goods associated with agriculture, manufacturing, and production. In India, a warehouse may be referred to as a godown.
A warehouse can be defined functionally as a building in which to store bulk produce or goods (wares) for commercial purposes. The built form of warehouse structures throughout time depends on many contexts: materials, technologies, sites, and cultures.
In this sense, the warehouse postdates the need for communal or state-based mass storage of surplus food.
The need for warehouses developed in societies in which trade reached a critical mass requiring storage at some point in the exchange process. This was highly evident in ancient Rome, where the horreum (pl. horrea) became a standard building form. The most studied examples are in Ostia, the port city that served Rome. The Horrea Galbae, a warehouse complex on the road towards Ostia, demonstrates that these buildings could be substantial, even by modern standards. Galba’s horrea complex contained 140 rooms on the ground floor alone, covering an area of some 225,000 square feet (21,000 m²). As a point of reference, less than half of U.S. warehouses today are larger than 100,000 square feet (9290 m²).
The need for a warehouse implies having quantities of goods too big to be stored in a domestic storeroom.
From the middle ages on, dedicated warehouses were constructed around ports and other commercial hubs to facilitate large-scale trade.
During the industrial revolution, the function of warehouses evolved and became more specialised.
The mass production of goods launched by the industrial revolution of the 18th and 19th centuries fuelled the development of larger and more specialised warehouses, usually located close to transport hubs on canals, at railways and portside.
Warehouses also fulfill a range of commercial functions besides simple storage, exemplified by Manchester’s cotton warehouses and Australian wool stores: receiving, stockpiling and despatching goods; displaying goods for commercial buyers; packing, checking and labelling orders, and dispatching them.
The utilitarian architecture of warehouses responded fast to emerging technologies.
A gabled roof was conventional, with a gate in the gable facing the street, rail lines or port for a crane to hoist goods into the window-gates on each floor below.
Technological innovations of the early 19th century changed the shape of warehouses and the work performed inside them: cast iron columns and later, moulded steel posts; saw-tooth roofs; and steam power.
Two more new power sources, hydraulics, and electricity, re-shaped warehouse design and practice at the end of the 19th century and into the 20th century.
20th-century technologies made warehousing ever more efficient.
The forklift truck was invented in the early 20th century and came into wide use after World War II. Forklifts transformed the possibilities of multi-level pallet racking of goods in taller, single-level steel-framed buildings for higher storage density. The forklift, and its load fixed to a uniform pallet, enabled the rise of logistic approaches to storage in the later 20th century.
Warehouses are generally considered industrial buildings and are usually located in industrial districts or zones (such as the outskirts of a city). LoopNet categorizes warehouses using the "industrial" property type. Craftsman Book Company's 2018 National Building Cost Manual lists "Warehouses" under the "Industrial Structures Section." In the UK, warehouses are classified under the Town and Country Planning Act 1990 as the industrial category B8 Storage and distribution.
Types of warehouses include storage warehouses, distribution centers (including fulfillment centers and truck terminals), retail warehouses, cold storage warehouses, and flex space.
These displayed goods for the home trade.
Richard Cobden's construction in Manchester's Mosley Street was the first palazzo warehouse. There were already seven warehouses on Portland Street when they commenced building the elaborate Watts Warehouse of 1855, but four more were opened before it was finished.
Cold storage preserves agricultural products.
Cold storage helps stabilize market prices and evenly distribute goods both on demand and timely basis. The farmers get the opportunity of producing cash crops to get remunerative prices. The consumers get the supply of perishable commodities with lower fluctuation of prices.
Ammonia and Freon compressors are commonly used in cold storage warehouses to maintain the temperature. Ammonia refrigerant is cheaper, easily available, and has a high latent heat of evaporation, but it is also highly toxic and can form an explosive mixture when mixed with fuel oil. Insulation is also important, to reduce the loss of cold and to keep different sections of the warehouse at different temperatures.
There are two main types of refrigeration system used in cold storage warehouses: vapor absorption systems (VAS) and vapor-compression systems (VCS). VAS, although comparatively costlier to install, is more economical in operation.
The temperature necessary for preservation depends on the storage time required and the type of product. In general, there are three groups of products, foods that are alive (e.g. fruits and vegetables), foods that are no longer alive and have been processed in some form (e.g. meat and fish products), and commodities that benefit from storage at controlled temperature (e.g. beer, tobacco).
Location is important for the success of a cold storage facility.
These catered for the overseas trade.
Behrens Warehouse is on the corner of Oxford Street and Portland Street. It was built for Louis Behrens & Son by P Nunn in 1860. It is a four-storey predominantly red brick build with 23 bays along Portland Street and 9 along Oxford Street. The Behrens family were prominent in banking and in the social life of the German Community in Manchester. 
The main purpose of packing warehouses was the picking, checking, labelling and packing of goods for export. The packing warehouses: Asia House, India House and Velvet House along Whitworth Street in Manchester were some of the tallest buildings of their time. See List of packing houses.
Warehouses were built close to the major stations in railway hubs.
The London Warehouse Picadilly was one of four warehouses built by the Manchester, Sheffield and Lincolnshire Railway in about 1865 to service the new London Road Station. It had its own branch to the Ashton Canal. This warehouse was built of brick with stone detailing. It had cast iron columns with wrought iron beams.
All these warehouse types can trace their origins back to the canal warehouses which were used for trans-shipment and storage.
A customised storage building, a warehouse enables a business to stockpile goods, eg, to build up a full load prior to transport, or hold unloaded goods before further distribution, or store goods like wine and cheese that require maturation.
Some of the most common warehouse storage systems are:
- Pallet racking including selective, drive-in, drive-thru, double-deep, pushback, and gravity flow
- Cantilever racking uses arms, rather than pallets, to store long thin objects like timber.
- Mezzanine adds a semi-permanent story of storage within a warehouse
- Vertical Lift Modules are packed systems with vertically arranged trays stored on both sides of the unit.
- Horizontal Carousels consist of a frame and a rotating carriage of bins.
- Vertical Carousels consisting of a series of carriers mounted on a vertical closed-loop track, inside a metal enclosure.
A "piece pick" is a type of order selection process where a product is picked and handled in individual units and placed in an outer carton, tote or another container before shipping.
Material direction and tracking in a warehouse can be coordinated by a Warehouse Management System (WMS), a database driven computer program. Logistics personnel use the WMS to improve warehouse efficiency by directing pathways and to maintain accurate inventory by recording warehouse transactions.
Some warehouses are completely automated, and require only operators to work and handle all the task. Pallets and product move on a system of automated conveyors, cranes and automated storage and retrieval systems coordinated by programmable logic controllers and computers running logistics automation software. These systems are often installed in refrigerated warehouses where temperatures are kept very cold to keep the product from spoiling. This is especially true in electronics warehouses that require specific temperatures to avoid damaging parts. Automation is also common where land is expensive, as automated storage systems can use vertical space efficiently. These high-bay storage areas are often more than 10 meters (33 feet) high, with some over 20 meters (65 feet) high. Automated storage systems can be built up to 40m high.
For a warehouse to function efficiently, the facility must be properly slotted*. Slotting addresses which storage medium a product is picked from (pallet rack or carton flow), and how they are picked (pick-to-light, pick-to-voice, or pick-to-paper). With a proper slotting plan, a warehouse can improve its inventory rotation requirements—such as first in, first out (FIFO) and last in, first out (LIFO)—control labor costs and increase productivity.
Pallet racks are commonly used to organize a warehouse.
Modern warehouses commonly use a system of wide aisle pallet racking to store goods which can be loaded and unloaded using forklift trucks.
Traditional warehousing has declined since the last decades of the 20th century, with the gradual introduction of Just In Time techniques. The JIT system promotes product delivery directly from suppliers to consumer without the use of warehouses. However, with the gradual implementation of offshore outsourcing and offshoring in about the same time period, the distance between the manufacturer and the retailer (or the parts manufacturer and the industrial plant) grew considerably in many domains, necessitating at least one warehouse per country or per region in any typical supply chain for a given range of products.
Recent retailing trends have led to the development of warehouse-style retail stores. These high-ceiling buildings display retail goods on tall, heavy-duty industrial racks rather than conventional retail shelving. Typically, items ready for sale are on the bottom of the racks, and crated or palletized inventory is in the upper rack. Essentially, the same building serves as both a warehouse and retail store.
Another trend relates to vendor-managed inventory (VMI). This gives the vendor the control to maintain the level of stock in the store. This method has its own issue that the vendor gains access to the warehouse.
Large exporters and manufacturers use warehouses as distribution points for developing retail outlets in a particular region or country.
Cross-docking is a specialised type of distribution center (DC) in that little or no inventory is stored and product is received, processed (if needed) and shipped within a short timeframe.
Reverse logistics is another type of warehousing that has become popular for environmental reasons.
There are few non-profit organizations which are focused on imparting knowledge, education and research in the field of warehouse management and its role in the supply chain industry.
Warehousing has unique health and safety challenges and has been recognized by the National Institute for Occupational Safety and Health (NIOSH) as a priority industry sector in the National Occupational Research Agenda (NORA) to identify and provide intervention strategies regarding occupational health and safety issues.