Urban decay is a process in which a previously functioning city, or city area, falls into disrepair and disuse. Common indications of urban decay are abandoned buildings and empty plots, high unemployment levels, high crime rates, and an urban landscape that is generally decrepit and desolate.
Urban decay has become associated with western cities, particularly in North America and Europe, as well as certain areas associated with the former Soviet Russia. It tends to be a feature of major cities which despite maintaining high property values in the inner city and central business district (CBD), and a thriving suburban area, have peripheral slums on the outskirts.
In the United Kingdom, the phrase ‘urban decay’ is often associated with ‘sink estates’ in cities, but can also be applied to seaside resort towns such as Morecambe and Skegness which have experienced falling tourist rates with the rise of low-cost air travel. In France, it is often associated with the banlieues of Paris, Marseille and Lyon. In the US, the most famous example of urban decay is in Detroit, which was hit particularly hard by the collapse of the motor industry.
 Socio-economic factors
There are many socio-economic factors that may lead to urban decay, including:
- Deindustrialisation, either by industry dying out or moving away.
- Depopulation or changing population, through ‘white flight’ (large-scale movement from urban areas to the suburbs).
- Restructuring of transport networks.
- Political disenfranchisement.
- Rent controls.
- Economic downturn and recession which may result in local businesses failing.
- Urban planning decisions.
- Prolonged riots and crime.
- Lack of new construction work or urban renewal projects.
- Environmental conditions, changes or disasters.
- Redlining (see below).
‘Redlining’ is the practice of directly or indirectly denying services such as banking, transport, health care or adequate shopping facilities, to the residents of certain areas. This became a particular problem in the United States during the 1970s/80s, where black inner city neighbourhoods were often discriminated against by banks and other businesses who refused aid and did not invest in the area.
 Urban blight
‘Urban blight’ refers to property that is in a state of decay and disrepair. A property can be said to be ‘blighted’ if:
- It is a public nuisance.
- It is fire-damaged or dangerous.
- It poses a severe and immediate health or safety threat.
- It is open to the elements and trespassing.
- It has had utilities and other services disconnected, removed or rendered ineffective.
NB: Property blight (sometimes referred to as 'planning blight' or 'blighted land') refers to the reduction in marketability and value of land as a result of a public sector decision, such as approval of a development that might result in the compulsory purchase of the land.
 Blight removal
There are several steps that can be taken to tackle blight removal:
- Property auctions.
- Nuisance abatement agreements.
- Partnering with groups and organisations in the community.
In September 2013, President Obama established the Detroit Blight Task Force to remove every blighted structure and clear every vacant lot in Detroit, Michigan, as quickly as possible using an environmentally-conscious approach.
The Blight Task Force defines neighbourhood blight as ‘all blighted residential structures, small commercial structures (less than 25,000 sq. ft lot size) and vacant lots’. There are 84,641 properties and lots in Detroit that meet this description, which includes around 40,000 unsalvageable buildings which will require demolition.
As of July 2016, an average of 75 vacant buildings had been demolished every week since 2014. The Task Force claim that they can remove all blight in five years or less, and estimate the total cost could approach $2 billion.
 Related articles on Designing Buildings Wiki
- Adam Curtis - The Great British Housing Disaster.
- Ballymun mass housing and regeneration.
- British post-war mass housing.
- Brownfield land.
- Listed building.
- Property blight.
- Sink estate regeneration plans.
- Social housing.
- Structures at the end of their design life.
- Urban design.
- Urban sprawl.
- Urban Task Force.
 External resources
- Time to End Blight - FAQs
Featured articles and news
CEOs and high-level executives explain who they expect to be the most successful players in the future of construction.
What are package contracts and how are they broken down? Find out in our introductory article.
Identifying sustainable shoreline protection solutions in the face of rising sea levels and storms in the US.
Budget documents state modern methods of construction will be favoured for public infrastructure schemes from 2019.
A walk-through exhibition of an emergency humanitarian shelter is officially opened at BRE's Innovation Park.
How to work safely on a construction site during winter.
Housing is the big winner in Chancellor Philip Hammond's Autumn Budget.
The winner of our BSRIA competition, Tomorrow's challenges in today's buildings, is.... Bob Hendrikx. A big thank you to everyone that took part.
Committee of MPs accuses government of dealing billpayers a 'bad hand' over the guaranteed power price.
In 1992, the Joint Fire Code was first published. What influence does it still have on construction sites today?
"Companies will have to adapt or go out of business" - how are virtual reality and big data disrupting digital construction?
International Well Building Institute and BRE collaborate on multiple levels to advance human health through better buildings.
"The industry has tried moving away from prescriptivism to focus on performance, but maybe that’s no longer working".