Incremental housing


Housing by the self-help incremental method is an important component in covering low-income households. It is stated elsewhere on this website that self-help housing production by low-income groups is declining, while middle-income groups are arriving increasingly on the housing markets. Self-help or self-managed housing by low-income households do not deliver sufficiently enough housing production, although it remains an important factor in individual home expansions and renovations. The finishing of the houses costs mostly very much time, while the urban population growth presses more and more on the cities and urban areas. Rising land prices caused by exploding urban housing markets makes housing for the poor even more too expensive.

Many national governments focus on promoting social housing, with more large-scale programs, where private builders and property developers realize ready-to-use subsidized projects with houses or apartments to sell to households. The housing products are often too expensive for persons or households with low incomes, while rental properties often are missing or unaffordable. Also, no attention is given to the needs of starters on the housing market and the elderly in most housing markets and policies. Another thing is that housing projects do not take into account the incremental finishing or growth of the dwellings.

Over the years, the private construction sector did not show interest in building low-cost housing. But sometimes social entrepreneurs show interest in low-cost housing for low-income groups. Also, often good initiatives are taken by NGOs with social housing programs, and small-scale cooperatives providing affordable homes for their members. All together this is too small-scale: urban housing production cannot be speeded up by incremental housing.

To serve low-income people with affordable housing, one should search for a different way of building affordable housing on a larger scale in urban areas. By the combination of self-help – and social housing a hybrid form of social housing emerges, whereby households who have limited incomes can also participate in a project but with a small core house or a starters house, and expand it over time. Consequently, incremental building is then included in social housing programs. It must be accepted by politicians and the local government that there is a greater differentiation in housing typology, and that some houses are only core houses or half houses. The costs of the land (or plots) must be kept low and dimensions of the plots must be kept small. Such a solutions refers to an organized core-house building, following the example of Ciudad Bachué, a large district of Bogotá in Colombia. Here a large-scale pilot project was realized with high density; all housing types were designed for incremental expansion, where the residents could play a crucial role with the expansion and the finishing of their homes. Main question is always: who organizes and finances in advance the early investments in the foundations and collective building structures and frames?

Starting points could be:

  • Mixed housing projects for different income groups in one neighborhood.
  • Higher housing densities also for persons who want to finish their houses by themselves.
  • Lowering the costs of the land (plots) and the dimensions of the plots.
  • People who do not built up their purchased lot, or do not finish their dwelling, have to sell back their property for the same price to the municipality or the building corporation, after a certain period.
  • Foundations and building structures must be completed in advance, and to be financed within a governed organization.
  • Homes can be delivered as completed ones or as grow-houses within a built-up building structure or framework.
  • Focus on sustainable construction methods and sustainable building materials.
  • Continue to focus on offering technical assistance for self-building households.
  • Transfer of technical knowledge, to the residents and the local communities.
  • Ensure that the low- cost housing leads towards an economic growth model that benefits the concerned residents group.

1          Pune, India, strategies by SPARC

Since 1986, SPARC has been working in India in partnership with two community-based organizations: the National Slum Dwellers Federation and Mahila Milan. Together, they are known as the Alliance. They center on individual housing in high density; which is seen in India as a slum improvement strategy.

Knipsel incremental housing by SPARC (2)

Above: Study of informal incrementality, its impacting factors and supporting systems by SPARC (2011)

Knipsel. r.presanai, pune india incremental  foto bouw gestapelde woningen 1 india pune

Above: (left) Models incremental housing in Pune (2012) architect Prasanna Desai; (right) Individual housing in Pune, India, according to SPARC’s densification system.

2        Bogotá, Colombia: Ciudad Bachué

ciudad Bachue, Bogota schema

One of the housing models in Ciudad Bachué: with initial provision, Planned and Unplanned expansions.

3             National Housing Authority of Thailand. By director of Department of Housing development studies. 10-11-2017 presented in Bonn, Germany.

Knipsel Thailand groeiwoning NHA  Knipsel Thai groeiwoning NHA

Building growth-houses at the start, with expansion possibilities on ground floor. Also semi-detached and row houses designed. This concept has great opportinities for incremental growth on ground floor.

4             Manaus, Brazil, Multi-story incremental proposal by Portugal, Harper and Shaikley.

schema manaus, portugal en HarperBuilding unfinished houses at start of project

5            Progressive housing in Cochabamba, Bolivia. By Ururu Architects, Bolivia.

Housing design: four concepts in one. Basic incremental housing contains: half a good house is a small house. Replace the reductionist logic (shrinking) by a synthesis principle. If the money is not enough for a house of more than 40 m2, it is an alternative to formulate the problem as progressive housing, as incremental housing. Incrementality should be designed. According to this vision informal self-help housing no longer can be seen as a problem and start to consider them as a part of the solution. According to common sense and the law of minimal effort, it is necessary to in the initial design to initiate another part that each family can reach the standard of the middle class.

Knipsel. vivienda progressiva. bron bolivia

Incremental housing – general information.

Incremental house building is a construction method that is used worldwide by millions of individual households. In the literature, different terms are used for the description of house construction methods that in principle have the nature of self-construction of houses by households. One can speak of ‘self-help housing’, ‘assisted self-help housing’, self-managed-housing’, and ‘incremental housing’.

Since the 1950s/1960s, it has been recognized that self-help housing is a very important factor in housing production. Self-help housing is based on the private power of the low-income households, which often have no other option but to create their own shelters. The possession of a private plot to build on is crucial. Institutional housing in the form of social or public housing was and still is missing in many developing countries. As a consequence, millions of households have to use their own labor, knowledge, materials and savings for the construction of their home, or otherwise, have to search for a rental facility. In the latter case, it is usually the private rental market that provides shelter, over and over again at high (market) prices. In the initial phase, self-built homes can be very simple, and regularly consist of waste material and second-hand building materials. In later phases, the houses are greatly improved and expanded step by step by the inhabitants themselves. They often make use of the help of family members and friends and sometimes hire skilled construction workers and small contractors for the execution of specialized works. However, not all households that start a building or renovation process, can or will succeed. In these cases, help from governmental or non-governmental organizations is necessary. Some local and national governments support this self-construction of homes. When this is the case, one can speak of ‘assisted self-help housing’.

Since the 1970s, international institutions such as the World Bank and UN-Habitat have recognized the vital role of self-help housing in providing affordable housing solutions to (and by) the urban poor. Even today the cities in the developing world have been built for a large part on the basis of informal self-building activities. Based upon the recognition of the enormous potential and capacity of self-builders to meet the urgent housing challenges, the mentioned international institutions started developing tools for public housing policies to assist the urban poor. National and local governments also adopted the notion of ‘assisted self-help housing’, by accepting rather than completely clearing squatter settlements and by facilitating the ‘incremental’ self-build processes in such neighborhoods. Incremental house construction implies a stage-wise informal building process, realized by individual families, only if and when their financial situation allows them to take further steps in the building process. This approach has the advantage of excluding the risks of long-term financial obligations in the form of mortgages. On the other hand, it means that the entire process of finishing a self-built house may take a long time. The adoption of policies supporting incremental self-help housing reflects a major break with earlier common practices, such as the eviction of the illegal inhabitants and the demolition of their provisional shacks in squatter settlements.

Since around 2000, the term ‘incremental housing’ has been used more and more. Some researchers have found that incremental self-help housing (or the step-by-step self-managed housing) is a phenomenon of great importance in housing production worldwide. Incremental housing can be defined as a gradual step-by-step process whereby building components are appended or improved by owner-builders as funding, time, or materials become available. In this way, the costs of housing construction can be reduced, especially compared with the housing delivery by contractors. Incremental housing requires flexible, relatively small short-term loans that are responsive to the intermittent demands of housing. In contrast, conventional mortgage finance requires enough funding to purchase or build a complete house. Incremental housing development can be an effective catalyst to engage people (social development) and to promote local businesses (economic development) of poor households and communities.

Latin America Housing Network (L.A.H.N.), University of Texas, Austin

Third Generation (3G) Housing Policies in Consolidated Low-income Settlements in Latin America. The research network comprises a multi-city comparative research project that was established in 2006. It includes leading researchers from the following countries and cities: Argentina (Buenos Aires), Brazil (Recife), Chile (Santiago), Colombia (Bogotá), Guatemala (Guatemala City), Mexico (Mexico City, Monterrey and Guadalajara), Peru (Lima), Uruguay (Montevideo) and the Dominica Republic (Santo Domingo).
Coordinator: Dr. Peter Ward.

MIT/SIGUS, Global Consortium for Incremental Housing

Informal builders provide the bulk of affordable housing and define large areas of our cities. Originally created for those long considered as poor and unable to house themselves, over time the resultant informal housing generally matches higher income standards. This incremental process has been adopted by governments into programmes called ‘site and services’, focusing on housing and land development, and embracing process as the key. A methodology to capture this process has been developed which offers a base for developing effective policies in supporting the incremental builders.
Coordinator: Dr. Reinhard Goethert.

Cities Alliance

The ‘Case for Incremental Housing’ by Patrick Wakely and Elizabeth Riley makes the case for governments to initiate and support incremental housing strategies as a major component of integrated urban development.

Documents on incremental housing:

Habitat for Humanity:
Shelter report 2014. Step by Step: Supporting Incremental Building Through Housing Microfinance

DPU Working Papers:
Urban public housing strategies in developing countries: whence and whither paradigms, policies, programmes and projects

Lund University:
Thesis Ivette Arroyo Baquero (2013) “Organized self-help housing as an enabling shelter & development strategy. Lessons from current practice, institutional approaches and projects in developing countries.”

The work of Architects: John Turner, Charles Correa, Balkrishna Doshi, Alejandro Aravena and others.

John Turner

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John Turner is a British architect who has written extensively on housing and community organisation, his writings being influenced by a formative period spent working in the squatter settlements of Peru from 1957-1965. There, Turner studied and advised on a number of reconstruction and slum upgrading programmes which were part of a nation-wide community development initiative. During this time Peru was also a leading centre for debate on housing policy, community development and the role of self-help housing. Turner’s own theoretical stance was formed in this context and combined aspects of the work of the Peruvian urban theorists Fernando Belaúnde, Pedro Beltrán and Carlos Delgado.

Turner’s central thesis argued that housing is best provided and managed by those who are to dwell in it rather than being centrally administered by the state. In the self-building and self-management of housing and neighbourhoods, Turner asserted that the global North had much to learn from the rapidly developing cities of the global South. Through a number of empirical studies, some of which were published in a collection for Habitat International Coalition entitled Building Community, he showed clearly that neighbourhoods designed with local groups worked better since people were experts on their own situations and should be given the ‘freedom to build’, a phrase that became the title for an edited collection by Tuner. Whether this freedom was granted by the state or wrested from it through squatting was less important. Within this framework the state as well as private professionals such as architects and engineers, act as enablers, resulting in a shift in thinking that valorises experience and local know-how over technocratic and professionalised forms of knowledge.

In contrast to the ‘aided self-help’ policies of the World Bank, for which Turner is frequently credited, his vision was far more radical as he not only contended that residents should build their own houses and neighbourhoods, but that they should also have control over their finances and management. In Freedom to Build: Dweller Control of the Housing Process, which was first published in 1972, Turner sets out these views, which remain relevant today. Whilst there have been some attempts in Europe to involve residents in decisions regarding their built environment, such as the work of the participatory architects of the 1960s and 1970s, the Scandinavian cohousing movement, the community technical aid centres of the UK and the work of architects such as Walter Segal, the full potential of such an engagement has not yet been realised.

Charles Correa

Charles Correa (1931-2015) was a great architect from India. He defined modern architecture in the country, moving on from the designs that Le Corbusier made in the new city of Chandigarh and in Ahmedabad in the early years after India’s independence. Correa acted as a President of the Indian National Commission on Urbanisation and was a pioneer in the field of affordable housing, and he constantly called attention to the crucial link between affordable housing, public transport and work areas. At the beginning of the 1960s he and two colleagues were advocates of this concept and they came up with a proposal for a radical restructuring of Mumbai (then called Bombay), where the growing number of illegal settlements in the city would be addressed. The then foreseen new town was designed to accommodate 2 million people and is now known as Navi Mumbai (New Bombay). By developing land on the other side of Bombay’s port, he would convert the North-South-development development axis of Mumbai into a poly centric urbanization model around the Bay. Navi Mumbai is a large-scale new town and one of the largest in the twentieth century. It is also the location of a smaller-scale experiment: the Belapur Incremental Housing project. As an architect Correa designed only one residential tower in his own city Mumbai, but this has become an iconic building, showing his Indian approach to architecture, using local building forms based on Indian living cultures. His Kanchanjunga apartments in Mumbai, 84 metres high, have courtyards in the air and luxury units that run from one side to the other to create through drafts.

Charles correa tower Source: Charles Correa Associates/ RIBA

Initially, Correa applied his ideas on housing and living to low, single houses, to incremental housing and to high-rise living. The ‘tube house’ in Ahmedabad (1962) is an early model of sustainable design for down-to-earth housing. It is a prototype of low-income housing, having a natural ventilation system and large living spaces; it was affordable as well as climate friendly. Only one tube house was built which finally was demolished in 1995. Nevertheless, the design is seen as iconic influencing the later work of Correa in the 1960 and 1970s, such as with the GHB-2 housing project (of the Gurajat Housing Board) in Ahmedabad, and designs for the PREVI (Experimental Housing Project) affordable housing project in Lima, Peru, where he showed the advantages of low-rise, high-density housing, with a cluster of incremental row-houses, with fluctuating widths, open-to-sky spaces and central double-height spaces covered by ‘wind-scoops’ for ventilation.

Knipsel tube house

Charles Correa’s work on housing has led to another iconic project, namely the Belapur Incremental Housing project realised in 1983 in Navi Mumbai. The project reveals the possibilities of the high-density, low-rise principle, based on a courtyard unit shared by a group of seven incremental houses. The project grew into a fully-fledged housing project to accommodate 600 households. The houses of the Belapur Housing are of one or two storeys, and were built traditionally, which fits well with the household’s life styles. The features are: high-density, incremental growth, small communities.

Knipsel ontwerp correa   charles-correa-hotels-apartments-townshipsresidences-30-638

Images : Charles Correa Associates/ RIBA

Balkrishna Doshi

The architect Balkrisna Doshi (1927) is another famous Indian architect who is dedicated to the social housing questions in India. He received the prestigious Pritzker Prize in 2018. The jury stated that “with an understanding and appreciation of the deep traditions of India’s architecture, Doshi united prefabrication and local craft and developed a vocabulary in harmony with the history, culture, local traditions and the changing times of his home country India”. During many decades Doshi created an extensive collection of educational, cultural, public administration buildings and residential projects. His designs reveal the architect’s relationship with building, history, tradition, culture, and modernism.

Architect Balkrishna Doshi designed the Aranya Low Cost Housing project that was realized in 1989 in Indore. The complex accommodates over 80,000 residents through a system of low cost housing with courtyards and internal pathways. The community is comprised of over 6,500 residences, amongst six sectors – each of which features a range of housing options, from modest one-room units to spacious houses, to accommodate a range of incomes. The homes were designed with extension and adaptability in mind. It won the Aga Khan award for architecture in 1995, and was praised for its integration of mixed-income groups. Balkrishna Doshi about the Aranya Low-Cost housing project: “They are not houses but homes where a happy community lives. That is what finally matters.” Furthermore he says: “It seems I should take an oath and remember it for my lifetime: to provide the lowest class with the proper dwelling.”

Knipsel ontwerp doshi  Aranya housing foto 1

Images: VSF

Other architects working on social housing and incremental practices.

The problem with social housing in developing countries is that almost all the constructions are done by households, while architects are hardly involved. Clearly, in these countries architects can – besides designing and constructing – also develop strategies for incremental housing, together with communities to achieve housing solutions that not only address today´s necessities, but that can also be extended over time as families grow, once again by themselves and later without architects.

Alejandro Aravena

A new generation of architects is demonstrating the ability to connect social responsibility, economic demands, design of human habitat and the city. With his group ‘Elemental’ the Chilean architect Alejandro Aravena – is the recipient of the 2016 Pritzker Architecture Prize. He and his team have been changing several design aspects of social housing, and also public policy concerning housing. What really sets Aravena apart is his commitment to social housing. Since 2000, he and his collaborators have consistently realized works with clear social goals. Calling the company a “Do Tank,” as opposed to a think tank, they have built more than 2,500 units using imaginative, flexible and direct architectural solutions for low cost social housing. The ELEMENTAL team participates in every phase of the complex process of providing dwellings for the underserved: engaging with politicians, lawyers, researchers, residents, local authorities, and builders, in order to obtain the best possible results for the benefit of the residents and society. An understanding of the importance of the aspirations of the inhabitants and their active participation and investment in a project, as well as good design, have contributed to the creation of new opportunities for those from underprivileged backgrounds. The role of the architect is now being challenged to serve greater social and humanitarian needs, and Alejandro Aravena has clearly responded to this challenge. Below: images of incremental growth in ELEMENTAL’s structures:

stringio elemental 1   elemental_3-960x701Source:

SPARC with and Prasanna Desai.

The architects have been doing research with (Society for the Promotion of Area Resource Centers) to develop an Incremental Housing Strategy that could be implemented anywhere. A team of international architects, urban planners, landscape architects and graphic designers volunteered to set up the strategy which uses the existing urban formations as starting point for development. Organic patterns that have evolved during time are preserved and existing social networks are respected. Neighbours remain neighbours, local remains local. When the architects started working the Indian government would initiate a grant of 4500 euro per family for making their homes incremental – at a national scale. The grant is now active and it can be given to any family who lives in a kaccha – an old temporary structure, not suitable for living. It is called City In-Situ Rehabilitation Scheme for Urban Poor Staying in Slums in City of Pune Under BSUP (Basic Services to the Urban Poor), and JNNURM (Jawaharlal Nehru National Urban Renewal Mission). The strategy strengthens the informal and aims to accelerate the legalization of the homes of the urban poor. Their strategy was arranged to fit the parameters of this grant. This study was done with SPARC and Mahila Milan (Women Together).

About SPARC: the Society for the Promotion of Area Resource Centers is one of the largest Indian NGOs working on housing and infrastructure issues for the urban poor. In 1984, when SPARC was formed, it began working with the most vulnerable and invisible of Mumbai’s urban poor – the pavement dwellers. SPARC’s philosophy is that if they can develop solutions that work for the poorest and most marginalized in the city, then these solutions can be scaled up to work for other groups of the urban poor across the country and internationally.
Since 1986, SPARC has been working in partnership with two community-based organizations the National Slum Dwellers Federation and Mahila Milan. Together, they are known as the Alliance. Today, the Alliance works in about 70 cities in the country and has networks in about 25 countries internationally. Sheela Patel, the Director of SPARC was awarded the Padmashree Award in 2011.

The Pune Municipal Corporation followed a participatory approach to implement an in-situ slum upgradation project under BSUP scheme of JNNURM to provide an alternative housing solution in high density slum areas of Yerwada region.

Collage-above-remy  in-situ rehabilitation scheme

Images by Filipe Balestra and Sara Söransson of Urbanouveau.

In situ-rehabilitation scheme in the scheme focuses on individual housing to be added in an existing neighbourhood. However, contemporary housing projects of the Gurajat Housing Board are more high-rise than in earlier decades, which is caused by the need to produce a huge number of dwellings each year. Incremental expansion of the dwellings is hardly possible herewith (see below).

Gurajat Housing Board projectSource: Gurajat Housing Board

Patricio Samper Gnekko, Ciudad Bachué

In Bogotá, Colombia, Ciudad Bachué is a high-density pilot project for social housing, that was built between 1978 and 1982. The project featured single and multi-family progressively expanded units, in total 7,124. Initially, the urban housing area Ciudad Bachué was located at the periphery of the Bogotá city centre, and later became well-connected to the city by various public transit lines. Meanwhile, the area is fully part of Bogotá’s urban fabric to the North. The project combines ten different housing types all less than 100 m2: five types are single family, five are multi-family, ranging from 1 to 5 story. All housing types were intended to be expanded progressively, except for the 4 and 5-story buildings with duplex apartments on top. Ciudad Bachué is a successful urban housing settlement, in terms of the experienced housing growth, and the evolution of community facilities and services of the settlement. Households of single-family and multi-family dwellings developed their homes within a built structure, which gave them the possibility to finish and refurbish their homes. One result of the incremental housing development is a sense of belonging, and a form of community development. The building blocks are small but incredibly dense and are mostly pedestrianised; only a few streets are wide enough to accommodate cars. The buildings are long and narrow with boxy additions stacked on top of the other onto the original structure.

Ciudad Bachué 1

Pedestrian street in ciudad Bachué. Photo by Chris Erb.