Construction is a general term meaning the art and science to form objects, systems, or

organizations,[1] and comes from Latin constructio (from com- "together" and struere "to pile up") and

Old French construction.[2] To construct is the verb: the act of building, and the noun is construction:
how something is built, the nature of its structure.
In its most widely used context, construction covers the processes involved in
delivering buildings, infrastructure and industrial facilities, and associated activities through to the
end of their life. It typically starts with planning, financing, and design, and continues until the asset is
built and ready for use; construction also covers repairs and maintenance work, any works to
expand, extend and improve the asset, and its eventual demolition, dismantling or decommissioning.
As an industry sector, construction accounts for more than 10% of global GDP (6-9% in developed
countries) and employs around 7% of the global workforce - over 273m people. The output of the
global construction industry was worth an estimated $10.8 trillion in 2017.

Contents

 1History
 2Construction industry sectors
o 2.1Building construction
 2.1.1Residential construction
 2.1.2Non-residential construction
o 2.2Infrastructure construction
o 2.3Industrial construction
 3Construction processes
o 3.1Planning
o 3.2Finance
o 3.3Legal
o 3.4Procurement
 3.4.1Traditional or Design-bid-build
 3.4.2Design-build
 3.4.3Construction management
o 3.5Design
o 3.6On-site construction
o 3.7Commissioning and handover
o 3.8Maintenance, repair and improvement
o 3.9Demolition
 4Industry scale and characteristics
o 4.1Economic activity
o 4.2Construction GVA by country
o 4.3Careers
 4.3.1Unskilled and semi-skilled workers
 4.3.2Skilled tradespeople
 4.3.3Professional, technical or managerial personnel
o 4.4Safety
o 4.5Sustainability
 5See also
 6References and notes

History[edit]
Main article: History of construction
See also: History of architecture
The first huts and shelters were constructed by hand or with simple tools. As cities grew during
the Bronze Age, a class of professional craftsmen, like bricklayers and carpenters, appeared.
Occasionally, slaves were used for construction work. In the Middle Ages, the artisan craftsmen were
organized into guilds. In the 19th century, steam-powered machinery appeared, and, later, diesel-
and electric-powered vehicles such as cranes, excavators and bulldozers.
Fast-track construction has been increasingly popular in the 21st century. Some estimates suggest
that 40% of construction projects are now fast-track construction.[3]

Construction industry sectors[edit]

Industrial assemblage of a thermal oxidizer in the United States of America

In general, there are three sectors of construction: buildings, infrastructure and industrial.[4] Building
construction is usually further divided into residential and non-residential. Infrastructure, also
called heavy civil or heavy engineering, includes large public works, dams, bridges, highways,
railways, water or wastewater and utility distribution. Industrial construction includes offshore
construction (mainly of energy installations), mining and quarrying, refineries, chemical
processing, power generation, mills and manufacturing plants.
There are also other ways to break the industry into sectors or markets.[5] For example, Engineering
News-Record (ENR), a US-based construction trade magazine, has compiled and reported data
about the size of design and construction contractors. In 2014, it split the data into nine market
segments: transportation, petroleum, buildings, power, industrial, water, manufacturing,
sewer/waste, telecom, hazardous waste, and a tenth category for other projects.[6] ENR used data on
transportation, sewer, hazardous waste and water to rank firms as heavy contractors.[7]
The Standard Industrial Classification and the newer North American Industry Classification
System classify companies that perform or engage in construction into three subsectors: building
construction, heavy and civil engineering construction, and specialty trade contractors. There are
also categories for professional services firms (e.g., engineering, architecture, surveying, project
management).[8][9]

Building construction[edit]
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Military residential unit construction by U.S. Navy personnel in Afghanistan

Building construction is the process of adding structures to areas of land, also known as real
property sites. Typically, a project is instigated by or with the owner of the property (who may be an
individual or an organisation); occasionally, land may be compulsorily purchased from the owner for
public use.
Residential construction[edit]
Main article: Home construction
Residential construction may be undertaken by individual land-owners (self-build), by
specialist house-builders, by property developers, by general contractors, or by providers of public or
social housing (eg: local authorities, housing associations). Where local zoning or planning policies
allow, mixed-use developments may comprise both residential and non-residential construction (eg:
retail, leisure, offices, public buildings, etc).
Residential construction practices, technologies, and resources must conform to local building
authority regulations and codes of practice. Materials readily available in the area generally dictate
the construction materials used (eg: brick versus stone versus timber). Costs of construction on a per
square meter (or per square foot) basis for houses can vary dramatically based on site conditions,
access routes, local regulations, economies of scale (custom-designed homes are often more
expensive to build) and the availability of skilled tradespeople.
Non-residential construction[edit]

Construction of the Federal Reserve building in Kansas City, Missouri

Depending upon the type of building, non-residential building construction can be procured by a wide
range of private and public organisations, including local authorities, educational and religious
bodies, transport undertakings, retailers, hoteliers, property developers, financial institutions and
other private companies. Most construction in these sectors is undertaken by general contractors.

Infrastructure construction[edit]
Main article: Civil engineering

Shasta Dam under construction in June 1942

Civil engineering covers the design, construction, and maintenance of the physical and naturally built
environment, including public works such as roads, bridges, canals, dams, tunnels, airports, water
and sewerage systems, pipelines, and railways.[10][11] Some general contractors have expertise in civil
engineering; civil engineering contractors are firms dedicated to work in this sector, and may
specialise in particular types of infrastructure.

Industrial construction[edit]

The National Cement Share Company of Ethiopia's new plant in Dire Dawa

Industrial construction includes offshore construction (mainly of energy installations: oil and gas

platforms, wind power), mining and quarrying, refineries, breweries, distilleries and other processing
plants, power stations, steel mills, warehouses and factories.
Construction processes[edit]
Some construction projects are small renovations or repair jobs, where the owner may act as
designer, paymaster and laborer for the entire project. However, more complex or ambitious projects
usually require additional multi-disciplinary expertise and manpower, so the owner may commission
one or more specialist businesses to undertake detailed planning, design, construction and handover
of the work. Often the owner will appoint one business to oversee the project (this may be
a designer, a contractor, a construction manager, or other advisor); such specialists are normally
appointed for their expertise in project delivery, and will help the owner define the project brief, agree
a budget and schedule, liaise with relevant public authorities, and procure the services of other
specialists (the supply chain, comprising subcontractors). Contracts are agreed for the delivery of
services by all businesses, alongside other detailed plans aimed at ensuring legal, timely, on-budget
and safe delivery of the specified works.
Design, finance, and legal aspects overlap and interrelate. The design must be not only structurally
sound and appropriate for the use and location, but must also be financially possible to build, and
legal to use. The financial structure must be adequate to build the design provided, and must pay
amounts that are legally owed. Legal structures integrate design with other activities, and enforce
financial and other construction processes.
These processes also affect procurement strategies. Clients may, for example, appoint a business to
design the project after which a competitive process is undertaken to appoint a lead contractor to
construct the asset (design–bid–build); they may appoint a business to lead both design and
construction (design-build); or they may directly appoint a designer, contractor and specialist
subcontractors (construction management).[12] Some forms of procurement emphasise collaborative
relationships (partnering, alliancing) between the client, the contractor, and other stakeholders within
a construction project, seeking to ameliorate often highly competitive and adversarial industry
practices.

Planning[edit]
Main article: Architectural plan

Digging the foundation for a building construction in Jakarta, Indonesia

When applicable, a proposed construction project must comply with local land-use planning policies
including zoning and building code requirements. A project will normally be assessed (by the
'authority having jurisdiction', AHJ, typically the municipality where the project will be located) for its
potential impacts on neighbouring properties, and upon existing infrastructure (transportation, social
infrastructure, and utilities including water supply, sewerage, electricity, telecommunications, etc).
Data may be gathered through site analysis, site surveys and geotechnical investigations.
Construction normally cannot start until planning permission has been granted, and may require
preparatory work to ensure relevant infrastructure has been upgraded before building work can
commence. Preparatory works will also include surveys of existing utility lines to avoid damage
causing outages and other hazardous situations.
Some legal requirements come from malum in se considerations, or the desire to prevent
indisputably bad phenomena, e.g. explosions or bridge collapses. Other legal requirements come
from malum prohibitum considerations, or factors that are a matter of custom or expectation, such as
isolating businesses from a business district or residences from a residential district. An attorney may
seek changes or exemptions in the law that governs the land where the building will be built, either
by arguing that a rule is inapplicable (the bridge design will not cause a collapse), or that the custom
is no longer needed (acceptance of live-work spaces has grown in the community).[13]
During construction of a building, a municipal building inspector usually inspects the ongoing work
periodically to ensure that construction adheres to the approved plans and the local building code.
Once construction is complete, any later changes made to a building or other asset that affect safety,
including its use, expansion, structural integrity, and fire protection, usually require municipality
approval.

Finance[edit]
Depending on the type of project, mortgage bankers, accountants, and cost engineers may participe
in creating an overall plan for the financial management of a construction project. The presence of
the mortgage banker is highly likely, even in relatively small projects since the owner's equity in the
property is the most obvious source of funding for a building project. Accountants act to study the
expected monetary flow over the life of the project and to monitor the payouts throughout the
process. Professionals including cost engineers, estimators and quantity surveyors apply expertise
to relate the work and materials involved to a proper valuation.
Financial planning ensures adequate safeguards and contingency plans are in place before the
project is started, and ensures that the plan is properly executed over the life of the project.
Construction projects can suffer from preventable financial problems. Underbids happen when
builders ask for too little money to complete the project. Cash flow problems exist when the present
amount of funding cannot cover the current costs for labour and materials; such problems may arise
even when the overall budget is adequate, presenting a temporary issue. Cost overruns with
government projects have occurred when the contractor identified change orders or project changes
that increased costs, which are not subject to competition from other firms as they have already been
eliminated from consideration after the initial bid.[14] Fraud is also an occasional construction issue.[15]
Large projects can involve highly complex financial plans and often start with a conceptual estimate
performed by a building estimator. As portions of a project are completed, they may be sold,
supplanting one lender or owner for another, while the logistical requirements of having the right
trades and materials available for each stage of the building construction project carries
forward. Public–private partnerships (PPPs) or private finance initiatives (PFIs) may also be used to
help delivery major projects. According to McKinsey in 2019, the "vast majority of large construction
projects go over budget and take 20% longer than expected".[16]

Legal[edit]
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remove this template message)
Main article: Construction law

Construction along Ontario Highway 401, widening the road from six to twelve travel lanes

A construction project is a complex net of construction contracts and other legal obligations, each of
which all parties must carefully consider. A contract is the exchange of a set of obligations between
two or more parties, and provides structures to manage issues. For example, construction delays
can be costly, so construction contracts set out clear expectations and clear paths to manage delays.
Poorly drafted contracts can lead to confusion and costly disputes.
At the start of a project, legal advisors seek to identify ambiguities and other potential sources of
trouble in the contract structures, and to present options for preventing problems. During projects,
they work to avoid and resolve conflicts that arise. In each case, the lawyer facilitates an exchange
of obligations that matches the reality of the project.

Apartment complex under construction in Daegu, South Korea

Procurement[edit]
Traditional or Design-bid-build[edit]
Main article: Design–bid–build
Design-bid-build is the most common and well-established method of construction procurement. In
this arrangement, the architect, engineer or builder acts for the client as the project coordinator. They
design the works, prepare specifications and design deliverables (models, drawings, etc), administer
the contract, tender the works, and manage the works from inception to completion. In parallel, there
are direct contractual links between the client and the main contractor, who, in turn, has direct
contractual relationships with subcontractors. The arrangement continues until the project is ready
for handover.
Design-build[edit]
Main article: Design-build
Design-build became more common from the late 20th century, and involves the client contracting a
single entity to provide design and construction. In some cases, the design-build package can also
include finding the site, arranging funding and applying for all necessary statutory consents.
Typically, the client invites several D&B contractors to submit proposals to meet the project brief and
then selects a preferred supplier. Often this will be a consortium involving a design firm and a
contractor (sometimes more than one of each). In the United States, departments of
transportation usually use design-build contracts as a way of progressing projects where states lack
the skills or resources, particularly for very large projects.[17]
Construction management[edit]
Main article: Construction management
In a construction management arrangement, the client enters into separate contracts with the
designer (architect or engineer), a construction manager, and individual trade contractors. The client
takes on the contractual role, while the construction or project manager provides the active role of
managing the separate trade contracts, and ensuring that they complete all work smoothly and
effectively together. This approach is often used to speed up procurement processes, to allow the
client greater flexibility in design variation throughout the contract, to enable the appointment of
individual work contractors, to separate contractual responsibility on each individual throughout the
contract, and to provide greater client control.

Design[edit]
In the industrialized world, construction usually involves the translation of designs into reality. Most
commonly (ie: in a design-bid-build project), the design team is employed by (i.e. in contract with) the
property owner. Depending upon the type of project, a design team may include architects, civil
engineers, mechanical engineers, electrical engineers, structural engineers, fire protection
engineers, planning consultants, architectural consultants, and archaeological consultants. A 'lead
designer' will normally be identified to help coordinate different disciplinary inputs to the overall
design. This may be aided by integration of previously separate disciplines (often undertaken by
separate firms) into multi-disciplinary firms with experts from all related fields,[18] or by firms
establishing relationships to support design-build processes.
The increasing complexity of construction projects creates the need for design professionals trained
in all phases of a project's life-cycle and develop an appreciation of the asset as an advanced
technological system requiring close integration of many sub-systems and their individual
components, including sustainability. For buildings, building engineering is an emerging discipline
that attempts to meet this new challenge.
Traditionally, design has involved the production of sketches, architectural and engineering
drawings, and specifications. Until the late 20th century, drawings were largely hand-drafted;
adoption of computer-aided design (CAD) technologies then improved design productivity, while the
21st century introduction of building information modeling (BIM) processes has involved use of
computer-generated models that can be used in their own right or to generate drawings and other
visualisations as well as capturing non-geometric data about building components and systems.
On some projects, work on site will not start until design work is largely complete; on others, some
design work may be undertaken concurrently with the early stages of on-site activity (for example,
work on a building's foundations may commence while designers are still working on the detailed
designs of the building's internal spaces). Some projects may include elements that are designed
for off-site construction (see also prefabrication and modular building) and are then delivered to site
ready for erection, installation or assembly.

On-site construction[edit]
Once contractors and other relevant professionals have been appointed and designs are sufficiently
advanced, work may commence on the project site. Typically, a construction site will include a
secure perimeter to restrict unauthorised access, site access control points, office and welfare
accommodation for personnel from the main contractor and other firms involved in the project team,
and storage areas for materials, machinery and equipment. According to the McGraw-Hill Dictionary
of Architecture and Construction's definition, construction may be said to have started when the first
feature of the permanent structure has been put in place, such as pile driving, or the pouring of slabs
or footings.[19]

Commissioning and handover[edit]

Main article: New-construction building commissioning
Commissioning is the process of verifying that all subsystems of a new building (or other asset) work
as intended to achieve the owner's project requirements and as designed by the project's architects
and engineers.

Maintenance, repair and improvement[edit]

Main article: Maintenance (technical)
Maintenance involves functional checks, servicing, repairing or replacing of necessary devices,
equipment, machinery, building infrastructure, and supporting utilities in industrial, business,
governmental, and residential installations.[20][21]

Demolition[edit]
Main article: Demolition
Demolition is the discipline of safely and efficiently tearing down buildings and other
artificial structures. Demolition contrasts with deconstruction, which involves taking a building apart
while carefully preserving valuable elements for reuse purposes (recycling - see also circular
economy).

Industry scale and characteristics[edit]

Economic activity[edit]
Helicopter view of the Atacama Large Millimeter/submillimeter Array (ALMA) Operations Support Facility (OSF)
construction site

The output of the global construction industry was worth an estimated $10.8 trillion in 2017, and in
2018 was forecast to rise to $12.9 trillion by 2022.[22] As a sector, construction accounts for more than
10% of global GDP (in developed countries, construction comprises 6-9% of GDP),[23] and employs
around 7% of the total employed workforce around the globe[24] (accounting for over 273 million full-
and part-time jobs in 2014).[25] Since 2010,[26] China has been the world's largest single construction
market.[27] The United States is the second largest construction market with a 2018 output of $1.581
trillion.[28]
In the United States in February 2020, around $1.4 trillion worth of construction work was in
progress, according to the Census Bureau, of which just over $1.0 trillion was for the private
sector (split roughly 55:45% between residential and nonresidential); the remainder was public
sector, predominantly for state and local government.[29]
Construction is a major source of employment in most countries; high reliance on small businesses,
and under-representation of women are common traits. For example:

 In the US, construction employed around 11.4m people in 2020, with a further 1.8m
employed in architectural, engineering, and related professional services - equivalent to
just over 8% of the total US workforce.[30] The construction workers were employed in
over 843,000 organisations, of which 838,000 were privately held businesses.[31] In March
2016, 60.4% of construction workers were employed by businesses with fewer than 50
staff.[32] Women are substantially underrepresented (relative to their share of total
employment), comprising 10.3% of the US construction workforce, and 25.9% of
professional services workers, in 2019.[30]
 In the United Kingdom, construction contributed £117 billion (6%) to UK GDP in 2018,
and in 2019 employed 2.4m workers (6.6% of all jobs). These worked either for 343,000
'registered' construction businesses, or for 'unregistered' businesses, typically self-
employed contractors;[33] just over one million small/medium-sized businesses, mainly
self-employed individuals, worked in the sector in 2019, comprising about 18% of all UK
businesses.[34] Women comprised 12.5% of the UK construction workforce.[35]
According to McKinsey research, productivity growth per worker in construction has lagged behind
many other industries across different countries including in the United States and in European
countries. In the United States, construction productivity per worker has declined by half since the
1960s.[36]