Kacca, Pucca, and Vernacular Architecture

In order to understand the architecture of urban informal settlement, we have searched its origins through a method that can be summarized as 'follow the people.' It is based on the logic that it is people who create buildings and that when people migrate; their way of building migrates with them. We will start with a look at where informal settlers come from and what architecture one finds there.

Migrants to the city generally come from the countryside, towns and villages. In the case of India, we could describe the migration chain as Tribal – Rural – Urban. We’ll use Tribal to designate those people who live in a close relationship with the forest, in pockets of only a few houses. Rural covers small villages based on agriculture, whereas towns and cities are urban.

What we see

An important marker of the difference in way of life of tribal people as compared to urbanites is the balance of indoor and outdoor activities. When much space is available around the house, as is the case in tribal settings, many of the daily activities take place outside. Therefore, there is limited need for indoor space. The house is mainly a place to keep things safe, whereas home activities stretch out around the house. The land around it is part of the realm of the home. The veranda is an item that expresses this hybrid notion of inside and outside very clearly. It is a sheltered outside and still part of the home. In a modern urban setting the home is confined to the house. Also, the near absence of windows in tribal architecture is an indicator of this outdoor oriented lifestyle. During the day, doors on both sides of the house afford cross ventilation. A small window is enough to allow daylight where needed, and often such a window is constructed in the roof. Windows in a wall would be a weakening of the protective function of that wall.

Photo 1. A mix of kacca and pucca. The walls of matting plastered with earth and cow dung are kacca, whereas the roof tiles and cemented base are pucca.

An often-noticed distinction in building techniques is that of kacca and pucca. A kacca house is built of earth and organic material, unlike the pucca house that is built of more durable materials like brick, stone, timber and cement. We’ll elaborate on this distinction below, since it is more sophisticated than a mere material difference. Pucca is understood as 'solid' and 'permanent', and comes from the Hindi word पक्का pakkā, which according to various Hindi-English dictionaries means 'cooked, ripe, solid, complete, inerasable, thoroughgoing, …' It is the opposite of कच्चा kaccā (also: kutcha) 'raw, unripe, crude, uncooked, unmade, careless, superficial, ...' Note that these meanings link to both the material and the process. Khosla (1983, p. 60) says about pucca that it "refers to the use of fired materials for the walls, like bricks or blocks; it also assumes […] a concrete or firm tile roof and all the ancillary specifications such as good flooring, doors and windows. Kutcha conversely […] implies mud walls, a temporary roof of thatch or country tiles."

How it works

Techniques

The logic of countryside architecture is to use locally available materials. From today's perspective this may seem primitive and due to a lack of means of transportation, but that is reverse reasoning. The absence of cheap transportation is the default situation; its availability is the exception. Moreover, it is simply irrational to put effort in transporting materials over long distances when adequate materials are at hand. In addition, every built structure needs maintenance and renovation, which is again easier without the logistics that come with the use of exotic materials.

Photo 2. Base and beginning of a wooden structure for a kacca house. All materials come from the site's immediate vicinity. The base is surrounded by a dry wall, i.e. without mortar or cement.

Local materials available to tribal people in the regions around Mumbai, are those that come from the forest: wood, twigs, leaves, earth; from riverbeds: reed, clay, mud, stones; and from livestock: cow dung, urine, hides, and hair. A typical kacca house is built on a base of earth contained in a low stonewall. A wooden structure of poles and beams bears the thatched roof. Walls are filled in with matting of leaves or wicker, and then plastered with layers of mud and cow dung. This plasterwork is essential in keeping snakes, insects, and rodents out. Cow dung is sticky and has a binding effect, but is easily damaged by termites. Mud is termite resistant, but brittle. By combining these characteristics, a sturdy termite resistant plasterwork is reached through the application of alternating layers of cow dung and mud. The cow dung's cellulose binds the sand grains, while the sand protects the cow dung from termites that typically have no appetite for mud. Earth floors are sealed using the same technique. Cow dung is dissolved in water and then used to wash the earth floor. Floors are washed this way approximately every week, a routine by which cracks get repaired, dirt is bound, and the floor becomes more solid over time. The result is a smooth dirt free floor, easy to sweep and pleasant to the feet. Its ability to 'breath' contributes to quality of the interior climate. Clearly, this technique requires frequent maintenance and consequently the house demands time from its occupants.

A pucca house is built of more permanent materials like bricks and roof tiles. Another distinction with kacca lies in the way materials are produced and acquired. Roughly one could say kacca materials are directly available from nature (or the environment at hand), whereas pucca first need processing like firing in a kiln. Note that kacca and pucca are comparative qualities, i.e. a material can only be qualified as more pucca in comparison to another material. The same goes for structures. An improvised dwelling is kacca compared to permanent settlement. Note also that pucca can be the result of applying a certain technique, without changing the material. A house built by craftsmen is likely more pucca than a DIY-one. In building improvement, the tendency is to move from kacca to pucca. In this thesis we use the term puccafication to refer to turning a kacca structure into a more permanent one.

The permanency of pucca materials and techniques inevitably makes it less easy to adjust the house to the needs and habits of the occupants. Through puccafication, the relationship between house and occupants becomes more rigid, more fixed. A kacca house can easily be adjusted, and in fact the occupant is in charge of how he and the house go together. In a pucca house, the structure is less flexible and the occupant will have to adapt to it. Of course people create a balance that suits them best. In the following we will show examples of balancing kacca and pucca for maximum flexibility.

A typical kacca house is built of a wooden structure with an infill of earth walls or wooden matting covered with earth and cow dung plaster. For puccafication, both the load-bearing structure and the infill could simply be replaced by brickwork. Brickwork has load-bearing capability, so a distinction between structure and infill is not necessary. For flexibility however, that distinction is very useful and the logical thing to do is to make the structure pucca while keeping the infill more kacca. Using the same bricks, masonry can be made in both a kacca and a pucca version by respectively using earth and cement for mortar. As a result, the wooden structure is replaced with columns made of brickwork with cement mortar, whereas the infill is made with earth mortar. This affords future changes and saves costs of cement.

Photo 3. The use of cement mortar in this corner column is a handshake of pucca and kacca. The wall is made of earth mortar masonry and allows easy future changes while keeping the main structure. The dentation on the left is a provision for future extension.

Photo 4. Earth mortar affords easy changing of a facade, as shown by the traces of the former doorway on the right

Photo 5. A ventilation grill is easily created in a kacca wall.

Photo 6. Kacca extension of a pucca house: earth mortar versus cement plaster.

The replacement of building elements in the gradual process of puccafication shows a certain order. This order can be understood from the perspective of rainwater management. The roof is the most basic protection against rain. Therefore, the introduction of pucca starts with roof tiles replacing thatch and leaves, as in Photo 7. Second, the raised level of the floor provides protection against flooding. The next pucca step is to mason the stones of the base's dry wall with cement mortar, as seen in Photo 1. The introduction of bricks is a third step, followed by the use of cement for mortar (Photo 3) and later for plasterwork (Photo 6).

Photo 7. A house built of the materials that surround it. The only pucca are the ceramic roof tiles. The rice thatch on top provides extra protection against the sun.

Brick making

Brick making is an activity that can be done by the household, but like with the production of rice, a surplus can be sold on the market. Nowadays, although it is still handwork, bricks are produced in an industrial manner. In the countryside it is often part of the local economy, especially when bricks can be produced from locally available clay rich soil. Such soil is found in riverbeds that are accessible during the dry season. The soil is mixed with water and sawdust, molded, and left to dry for several days. Then the green bricks (fired bricks are red) are stacked with thin layers of sawdust and coal between them, resulting in a stack that is a kiln at the same time. Stacking and fueling is a very precise job and requires the presence of experts. Fuel must be applied evenly and balanced since, once the kiln is lit, it is impossible to make adjustments. The kiln must be densely packed to keep the heat in and thus generate high temperatures, yet allow sufficient airflow for the burning.

Photo 8. Brick making starts with molding clay-rich soil and drying the raw bricks for several days.

Photo 9. Clay-rich soil needed for brick making is typically found in riverbeds, which are only accessible during the dry season. Therefore, brick maker's houses are temporary and kacca.

 The firing itself takes about ten days. Then the stack can be unpacked and the quality of the bricks assessed. Bricks at the core have received the most heat and are therefore of the best quality. The bricks on the outside are of the least quality and often not suitable for use in building. In order to reduce this gradient in quality, the outer skin of the kiln is built as a separate structure, much like a cavity wall. This way the stack is insulated and as the heat stays inside, it will spread more evenly and contribute to a more constant quality. Bricks of too poor quality, provided they are not broken, are left on the spot and used again for the skin of the next kiln.

Photo 10. Unpacking a kiln and rebuilding it for a next round. The firing process changes the color of the bricks from green to red. Insufficiently fired bricks are reused in the skin of next kiln.

Bricks of sufficient quality are used for building throughout the region, including the city of Mumbai. Note that transportation is only required after completion of the product. All phases of the production process take place on the same spot, and only the small amount of coal is transported towards it.

Brick making is a dry-season activity, as it requires access to the riverbed and the drying of green bricks. Consequently it alternates with rice cropping, which is a typical monsoon activity, and it is common practice in families to work in both farming and brick making. In addition to this pattern, the same brick makers can be found as construction workers in the city during monsoon.

Brick making being part of the local economy brings puccafication to tribal people's doorstep. Government supported improvement schemes help people to replace kacca walls with masonry. In practice this means that people dismantle their house and rebuild it with bricks and cement. Since it is not possible to rebuild a house overnight, the occupants stay temporarily with neighbors or family.

Photo 11. Rebuilding pucca. Cement is a marker of puccafication.

Photo 12. This makeshift house is profoundly kacca as it is made of readily available kacca demolition waste.

What it tells us

We already saw that the distinction between kacca and pucca is a relative one, i.e. can only be made when comparing two materials, structures, or techniques. A house built of masonry is more pucca than a straw bale house, whereas compared to concrete masonry is more kacca. So far we have focused mainly on physical properties, but as already mentioned, the way of acquiring, processing, and producing materials is a distinguishing factor too. As suggested by Caimi & Hofmann (2005), techniques as such can make structures more pucca, for example by weaving materials or designing roofs with a larger overhang. There are actually many building characteristics that can be understood in a dialectic of kacca and pucca, and we have collected some in Table 1.

Kacca	Pucca
Ephemeral	Permanent
Occupant makes adjustments to building	Occupant has to adapt to building
Durability depends on skills	Durability comes from material
High maintenance	Low maintenance
Do It Yourself	Outsourced
Everyday	Specialized
Crude	Craftsmanship
Pragmatic	Systemized
Vernacular	Market
Custom-made	Ready-made
Readily available materials	Processed materials
Low impact on environment	High impact on environment

 Table 1. Building characteristics categorized in a kacca - pucca dialectic.

  

Photo 13. Example of the kacca - pucca dialectic in Swiss construction: light weight masonry versus in situ cast concrete. Rue du Centre, St-Sulpice VD.

Puccafication is also related to changes of lifestyle. Mrs. Patil for example, used to live in one of the last remaining kacca houses in her village. Although she appreciates the fine qualities of the kacca architecture, her job as a teacher does not leave her sufficient time to do the maintenance the house required. She explained to us that the modern lifestyle based on the nuclear family[1] instead of the joint family[2], is only affordable when one earns enough money, i.e. when one has a job outside the home. The necessary frequent washing of cow dung floors and earth walls is simply too time consuming. Moreover, the income she generated with her job as a teacher, allowed Mrs. Patil to have her house converted into a pucca one. We spoke with her just two weeks before the house was to be demolished and rebuilt pucca. She expected important changes in her relationship with the house as her home, since she had already noticed such changes when she changed her source of income. For example, before taking a full job as a teacher, farming was the main livelihood. From the day Mrs. Patil sold the 30 cows that were part of the household, all kind of problems started to occur, one of them mosquitoes feeling free to come inside. The scent of cow urine is a natural mosquito repellant, and the departure of the cows meant the introduction of potentially infectious insects in the home. In the tropics of course this is a big thing. The absence of cows also deprived the household of its source of cow dung and thus directly undermined maintenance of the house. Not only had modernization made her change her household, it also brought her the need to take artificial measures against diseases. Mrs. Patil foresaw more of such changes, but nevertheless felt compelled to have her house rebuilt pucca, since "everybody in the village does so and living in an old fashioned house will not be good for my reputation as a school teacher."

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[1] A nuclear family consists typically of a couple and their children.

[2] The joint family includes grandparents, aunts and uncles.

 

Photo 14. Mrs. Patil's kacca house two weeks before replacement with a brickwork-and-cement version. The neighbors already changed to pucca.

Photo 15. Mrs. Patil's kacca house, kitchen area.

Photo 16. Pucca house in the same village, showing extensive use of cement.

The story of Mrs. Patil shows how people and buildings become independent from each other in what is called modernization. In a kacca house, everyday life activities are closely related with the house and the house cannot survive without the frequent support of the human hand. In pucca, the house becomes less dependent on the occupant vice versa, i.e. the two get disconnected.

A step much further on the line towards pucca is that from a ground bound dwelling to a multistory condominium. Mr. Korde used to live with his mother, three brothers, and three sisters in a small two-room chawl until it was sold for redevelopment. Part of the arrangement was a free of costs condominium for Mr. Korde on the fifth floor in the new to build concrete eight-story high-rise. He now lives there with his wife and his daughter. As Mr. Korde gently put it: moving from the chawl to the condominium was 'upsetting'. He immediately added that he could not sleep for six months. He felt it was 'not his house' and missed the social environment of the chawl. Note that Mr. Korde's change of house type coincides with the change from joint to nuclear family. Besides the social and psychological aspects, he argued that concrete is a problematic material for many reasons: the concrete becomes much too hot to be comfortable, it has poor tactile qualities, and it comes with an inherent impossibility to change the layout of rooms or make even the smallest hole in a wall. Concrete is too pucca. The thing he appreciated most in his former (more kacca) chawl was the cow dung floor. 

Photo 17. Mr. Mathre is maintaining the cow dung floor around the house by washing it with a mix of water and fresh dung.

Mr. Santosh N. in P. also laudes the qualities of cow dung floors. The house he lives in together with his joint family has gradually become more pucca. Since sleeping is mostly done on a mat on the floor, the difference between cow dung and tiles on concrete are felt clearly. A cow dung floor has more moderating capacity, i.e. it maintains constant temperature and humidity. According to Mr. Santosh, floor tiles give more health troubles and for that reason the family decided not to put tiles in the kitchen.

Photo 18. Mr. Vadu and his family abandoned their pucca house on the left and prefer living in their new house on the right.

Pucca is not necessarily better than kacca, as the above has already shown. There are people who move back to kacca, like Mr. Vadu for example. He lives in a house with kacca walls now, next to his former more pucca house. The kacca house however has a roof of corrugated fiber cement panels, so maintenance is kept to a yearly round of plastering the walls. The pucca house with its masonry cement-plastered walls is abandoned. The cemented walls and floors had an unpleasant effect on the interior climate and were difficult and expensive to maintain. Mr. Vadu is an artist and expert in Warli-painting. We will discuss Warli painting and its relation with architecture in a separate chapter. Mr. Vadu prefers the kacca house because it fits better with the artwork and his profession. In order to give maximum protection against wind and animals, e.g. tigers, the kacca house has no windows. Doors on both sides of the house afford cross-ventilation.

Photo 19. Mr. Vadu's house is deliberately equipped with kacca walls. In order to create maximum protection against animals, there are no windows.

The above illustrates that the kacca – pucca distinction is a relative one and that it applies to both material and construction. Combinations of kacca and pucca are common. The preference for more kacca or more pucca can be based on practical reasons, e.g. comfort and maintenance; social reasons, e.g. status; or psychological reasons, e.g. well-being.

Puccafication in tribal areas has raised concerns among experts as it might lead to loss of culture and create environmental issues. In government supported schemes to improve tribal housing and help people create pucca houses, restrictions on the use of cement are an important tool to curb such effects.

In the next chapters we will see that skills and way of life go with the people. In the chapter about pavement dwelling for example, we will see the kacca – pucca distinction again, albeit with the same people but different locally available materials, and different sociologic context. 

Photo 20. The use of color paint is a marker of permanency.

Photo 21. Expressive and exotic colors are found on houses of the higher, often wealthier, castes.

References:

Caimi, A. and Hofmann, M. (2005). From Kutcha to Pucca. Proposition de reconstruction d'habitats résistant aux calamités naturelles pour les villages de l”Orissa (Kendrapara District, Orissa State, Inde). http://infoscience.epfl.ch/record/127951 

Khosla, R. (1983). Architecture of Rural Housing: Some Issues in India. Social Scientist, 11(4), 56–60. doi:10.2307/3517024

To zone or not to zone

Why official planning doesn't work in hyper dense areas

The applicability of contemporary strategies of urban planning is under increasing scrutiny when it comes to dealing with equitable housing in swelling cities. There is a growing awareness of the limitations of urban planning, as we know it. A first step towards new strategies is recognising that the chaotic urbanism of informal settlement holds lessons of how cities can be built without zoning or regulation. Studying such areas offers a tabula rasa in thinking city planning. A useful case to study user generated urbanism is in informal settlement area. It shows both the power of informality and the counterproductive effects of zoning in hyper dense areas. To get a sense of what density means in informal settlements, we need some figures. In developed countries, well known dense cities are New York City (10,500 p/km2) and Tokyo (14,000) . Estimations of the density in informal settlements show figures that reach from 300,000 to over 400,000 p/km2, which is more than ten times that of Cairo (31,600), world’s densest city. Considering that in swelling cities often over 50% of urban population lives in informal settlements, while occupying only 5% of the land, it is clear that overwhelming densities are found widely and that as a result, the pressure on open space is enormous.



Photo 1. Big open public space found in informal settlement area, hosting a cricket match.



Photo 2. The surrounding houses double as tribunes.

The presence of wide open public space is probably not the first that comes to mind when imagining the effects of high population densities. Miraculously, wide open spaces do exist in informal urbanism. They serve many purposes, such as cricket ground, community gathering and playground for all. Obviously, there is the everlasting threat of newcomers who seek a place to put up a shelter. However, somehow against that incoming tide of squatters, communities manage to keep space open.




Photo 4. Public gathering in a squatter area.

One of the secrets behind surviving in such very high densities lies in the multipurpose use of both public and private space. The recipe for successful multipurpose use is to rely on the power of informality. It is typical that most westerners who visit extreme dense areas for their first time, point at the lack of zoning in the streets. They claim that sidewalks are needed to make traffic safer, that curbs would help, as would separate lanes for hand carts. It is the planner’s mind that, in the name of ‘order’, introduces all kinds of obstacles in public space, forcefully introducing formality. What they apparently do not see is that zoning itself is space consuming. By allotting space to specific activities, that space is rendered useless for other activities that take place at different moments in time. Only non-designated space can be used all day long, meeting needs exactly when they occur.




Photo 5. Informality at its best: user generated zoning.

There is an interesting parallel between urban design and the design of rooms in housing. In western housing design, rooms are designed for a specific use. Rooms get a function and are named after it. Bed room, study, kitchen, living room, etcetera. This segregation leaves many rooms unused for most of the time, much unlike the traditional Japanese house in which the function of the room changes during the day. By changing futons and furniture, the room is adapted to what is needed. The key to traditional Japanese design is the creation of an open plan. Everything can change as no elements are fixed, even walls can move by means of sliding partitions. When everything is moved to the side, a smooth, obstacle free floor is all that remains.
On a more detailed scale, furniture is a similar institutionalisation of use. The introduction of chairs and a table reduces the use of a room to sitting around a table. The absence of furniture makes it possible to use a room for whatever comes up. Especially chairs are indicative for this phenomenon. In smaller homes, chairs are often the first item no longer to be found. Sitting can be done on the floor or on a bed doubling as a sofa.
It is exactly this concept of a smooth obstacle free floor that is the most successful formula for multipurpose use of public space. Activities and the number of people involved in them change throughout the day, as do the areas occupied by them. By leaving the boundaries between activities unmarked, these boundaries can freely move to an optimum.




Photo 6. Use of the street around 10am. Few people and little traffic.

The daily routine on an average main road could look like this. In early morning, the street is relatively empty. Commuters walk to the railway station, buying a take away drink from early vendors. Waste collection is present as always. Busses and cars drive by. By ten o’clock, shopkeepers start opening their business. Some street vendors start exhibiting their merchandise. Around 11 am, road traffic is increasing. Pedestrian presence slows the trucks and busses down. Noon. As the tropical heat is increasing, pedestrians and vendors leave the scene. Car traffic becomes predominant. Between 3 and 4 pm, vendors take over the street again, this time en masse and hold their ground till 10 pm or later. Meanwhile Muslims do their prayers, thus creating a temporary open air mosque. Taxis drive by all day and continue all night.




Photo 8. Around 6pm. The street is converted into a marketplace.



Photo 9. Friday prayers. Part of the street is converted into a mosque.

All activities claim space, put pressure on other activities and then later allow others to take over space again. This flow in the use of space is most efficient when it is not hindered by physical markers such as curbs, fences, boulders, or even walls. Moreover, such street furniture items can be counterproductive in densely used areas, as they mainly split the ever-moving zones of activities rather than limit them to the intended space. In Rahul Mehrotra’s terms, the static city is at odds with the kinetic city here (1). The static city is the physical city as it is built; the kinetic city is made by the events that take place in a city. Ideally, the static and the kinetic city are in harmony.




Photo 10. Counterproductive zoning. The fence on the curb inhibits pedestrians returning to the sidewalk.

Especially fences on curbs along the sidewalks show how informal forces override the intentions of planners and urban designers. Such fences are designed to keep pedestrians on the sidewalk and to reserve the road for motor vehicle traffic. The sidewalk however is the realm of shopkeepers, street vendors, and their customers and can be so crowded that non-customers prefer to walk on the other side of the fence. Once there, it is hard to return to the sidewalk, making the whole scene less safe than without the fence.




Photo 11. Counterproductive fixed zoning. Passengers at this busstop have to wait at the traffic side of the fence, as otherwise they cannot enter the bus.



Photo 12. User generated rezoning. Street vendors using the fence as an ideal backing, knowing that the traffic is what brings customers.

In addition, this parallel flow of pedestrians is seen by street vendors as potential clientele, so the vendors pick a spot on the road side of the fence. Moreover, the fence provides a nice backing. Thus a second lane of vending activities is created, reinstalling the informal multipurpose use of space, squeezing the vehicle traffic space even further than would have been the case without the fence. In an attempt to make the fence (i.e. zoning) effective, authorities have declared street vending illegal. Policemen have a tough job enforcing this ban as they are highly outnumbered by their targets. As soon as a raid starts, the news spreads like wildfire. Vendors pick up their merchandise quickly and hide it behind a tree, a lamppost, in the subway or even in the shop of a friend legal shopkeeper. After ten minutes, when the police have left the unlikely empty street, vendors put up their business again and continue as usual.
The issue here is the incredible density of people. Of course zoning and planning do work, as long as capacities meet the numbers. When congestion occurs, people start looking for shortcuts and challenge the planned zoning and formality as a whole. Shortly the cure (zoning) becomes worse than the disease, especially when zoning is embedded in physical objects. As we have seen, physically manifested zoning of use is space consuming and for that reason a problem when dealing with hyper densities. The kinetic city is very much an alive thing, as it is capable of permanently adapting itself to the context. This ongoing adaptation marks the efficiency of user-generated zoning in informal settlement. In fact the difference between formal zoning and user generated zoning is the use of time, the use of the fourth dimension. It is what allows space to be used 24/7.
New strategies should give a significant role to informality. It is time to overcome the limitations of 20th century urban planning and enter the realm of Post-Cartesianism. A clear invitation to come and see the wonders of informal urbanism was sent by Alfredo Brillembourg and Hubert Klumpner in the documentary Caracas, The Informal City (2). Klumpner says about Caracas: “But why do I feel as a European that this city is a total chaos? I think it is a typical response. There is a myth that the city is ordered and that myth exists in city halls around the world. The reality is however, that the city has always been chaotic. In Caracas all these forces stream freely and have produced new forms of city that are not known to us.”


1 Rahul Mehrotra, ‘Kinetic City, Issues for Urban Design in South Asia’. In: Shannon, Kelly and Gosseye, Janina (eds.), Reclaiming (the urbanism of) Mumbai (Amsterdam, SUN Publishers, 2009) pp. 141-9.
2 Rob Schröder, Caracas, The Informal City. Documentary for VPRO television The Netherlands, http://tegenlicht.vpro.nl/backlight/Caracas-the-informal-city.html

Corrugated Steel

Emblematic for the other architecture



Photo 1. Mexican restaurant in Ebisu, Tokyo, Japan. A welcome natural look between the average contemporary but sterile architecture. Corrugated steel in all its splendour.

Corrugated steel is probably the most iconic of all building materials used in squatter settlements. It is a versatile product as it is strong, watertight, easy to cut, and above all cheap. To many of us, corrugated steel may look ordinary and simple but it is exactly this simplicity which makes it such a brilliant invention. The core of it all is, needless to say, a steel sheet with a thickness of only 1 mm. Such a sheet can be bent or folded in any direction, as a flat sheet has limited stiffness. It is the corrugation which adds the typical structural character. A corrugated steel plate can easily be bent in one direction, whereas at the same time it is very rigid in the other direction.

The production of steel plate is straightforward. Solidified steel bars are rolled until they have the required thickness. Cutting is as easy as cutting paper. Then comes corrugation which requires the most basic of all machines. Let’s say that a classic machine has gear wheels. A corrugation machine would consist of two gear wheels only, nothing more than that. Turning one wheel will automatically turn the other wheel . By feeding a flat steel plate between the two wheels, a regularly corrugated steel plate will appear on the other side of the wheels. The process is beautifully simple.

The resulting wave form sheets are excellent for roofing. Due to their stiffness the sheets need limited structural support. Much like ceramic roof tiles, a limited overlap of sheets will result in a water tight roof. The corrugation prevents leakage to the sides of the sheets.



Photo 2. Corrugated steel in detail, thin like a curtain. Corrosion is typical for re-used sheets.

Steel and water are not exactly friends, which is why steel plates corrode. To avoid this corrosion, steel plates are bathed in molten zinc, a process called galvanising. The zinc keeps the water out and even inverts the corrosion process of steel. Zinc has self healing properties in case of damage of the zinc layer, be it to a certain extent. Galvanised steel can therefore not be bent, under pain of corrosion. This is probably why recycled corrugated steel sheets have a limited life, as in the process of demounting, they are often bent more than is advisable.

Photo 3. Temporary housing for road construction workers. Alibag, Mumbai, India.

The use of corrugated steel for housing has certain drawbacks. Due to its thinness, it has zero insulation capacity, leaving the interior virtually fully exposed to the fierce tropical sun. In the rainy season steel roofs are extremely noisy. It means that corrugated steel creates comfort problems all year round. This is probably why in Mumbai the use of corrugated steel is limited to the temporary housing of construction workers on building sites. Such housing is often provided by the construction company, in which case it is the easiest (i.e. cheapest) material to use. Those people who create their own shelter apparently prefer other materials than corrugated steel. It is something to consider in rehabilitation projects too.

Photo 4. The architecture of the other end. Sheets made in mass production, thought of as a system of repetition, applied in a system-less order.

As the production process is so simple, corrugated steel is ideal for mass production. By its form, it is ideal for covering large surfaces such as roofs and facades, as that would require the least of handling per sheet. This is what distinguishes the architecture of settlements from architectural design. The latter most of the times is an attempt to make something special with materials best used in a system of endless repetition which fails where it meets other systems , whereas settlers are inventive in making something unique with individual sheets, not hindered by any system at all.

The emblematic value of corrugated steel in squatter settlements lies in the fact that it is indicative for the poorest ways of creating shelter and for the poorest ways of offering relief.

Removal

The only way is: up?

Photo 1. Slum rehabilitation in Andheri West, Mumbai.

A library of considerable size could be filled with all that is written about slum rehabilitation. A seemingly endless number of studies, schemes, plans, proposals, surveys, scenarios, evaluations, and elaborations are made by a similarly endless line of planners, developers, urbanists, architects, authorities, slum lords, students, social experts, economists, engineers, real estate investors, associations, communities, contractors, governments, NGO’s, and so on. The phenomenon is thus big that books (1) are written about it as such, in a variety of qualities (2).



Photo 2. Apartment block towering over Thirteenth Compound, Dharavi, Mumbai.

There is little use in coming up with another plan here. Nor is it doable to explain all strategies being used. This chapter will be limited to how people move from informal settlements to housing and back(!). A short abstract on the mechanisms of rehabilitation is inevitable though.
Slum forming is the result of mass migration into the city combined with too short supply of proper housing. Migrants create their own shelter on whatever space is available, turning the city into a vast campsite. The scale of it leads to incredible densities, leaving little space for the development of adequate housing. Replacing informal settlements by houses, requires a strategy of removing settlers to a temporary location, clearing the land, building new housing, and relocating the settlers into the new building.



Photo 3. Transit camps in Andheri West, Mumbai.

Temporary locations are called transit camps. These transit camps appear in a variety of forms. Some look like stacks of cabins, others mimic apartment blocks. One area in Dharavi, the New Transit Camp, was mainly a handing out of parcels of land allowing people to restart their dwelling-career. By now it is an area of certain urban quality as the inhabitants were able to generate their own housing, upgrading it bit by bit, backed by security of tenure.



Photo 4. Stages of planned redevelopment. Slum on the right, transit camp on the left, construction and relocation in the background. Andheri West, Mumbai.



Photo 5. The demolition of abandoned slum reveals its inner structures. The soil contains an archaeology of the recent past.



Photo 6. As every boy in the world knows, construction sites are perfect playgrounds.



Photo 7. Incremental development (left) and planned redevelopment (high-rise) in Dharavi, Mumbai.

The landscape of Dharavi is permanently changing. In the sea of informal settlements many upgraded houses appear in the user generated process of incremental development. It is a natural process in which end-users change and adapt their environment directly. And thus it will deal will the issue of too high densities as well. It guarantees that every unique need gets its own unique solution. It is the process by which the much loved organic downtown cities throughout the world have evolved. The crucial thing is: this humane process cannot be hastened.
Probably it is the subtlety of this generating process that leaves many using the word slum for areas that are beyond that poor early stage. Moreover, it is spatially intertwined and gradual in time, making it harder to distinguish and appreciate the qualities of incremental development.




Photo 8. Planned redevelopment in Dharavi.

Meanwhile some larger areas are cleared for planned redevelopment and filled in with apartment blocks. More and more blocks are shaping the skyline. As long as there is a piecemeal approach in this kind of development, it has the possibility of adapting and mitigating the worst side effects of high-rise.



Photo 9.Babasaheb Ambedkar Nagar, Parel, Mumbai. Four blocks of low cost housing for former slum dwellers, flanked by high-end apartment blocks and office high-rise.

Building high-rise blocks too close to each other is where many a solution is becoming an enhanced version of the original problem. The cause lies in the scheme by which the project is financed. Authorities allow developers to create profitable high-end housing in exchange for providing housing for the poor, free of costs. This scheme is popular among developers and works quite successful in the sense that it is producing a lot of low end housing. It goes without saying that the land used to create the free housing for the poor, is kept to a minimum. By creating lots of floor area (the essence of high-rise building) the available living space per capita is forced up to the legal minimum. Still the density in terms of land per capita is problematic and sometimes even worsens. Amenities such as infrastructure, transport, commerce, schools, utilities, and qualities like daylight and fresh air are all heavily over utilised.



Photo 10. Babasaheb Ambedkar Nagar seen from Parel railway station, Mumbai. A recipe for vertical slum.

Huge blocks are built only 10 feet apart. The effects on the quality of living are dramatic. Dwellings in the centre of such three dimensional compounds enjoy little daylight and near to no natural ventilation. Not to mention the lack of privacy and the absence of psychological relief by a view from the window. In addition, the images of newly built fresh painted condominiums are deceiving as such no-revenue projects come with a standard lack of maintenance and thus pauperize in a short time. Living on one of the higher floors will inevitably turn out troublesome as elevators are not maintained either, which is a well known reason for not building higher than four or five floors for low income housing. Buildings offering such living conditions are often rightfully categorised as vertical slums. They are the planned version of the City of Darkness (3), the Kowloon Walled City in Hong Kong which was at its peak in the 1980’s home to some 35,000 people on a footprint of only 100 x 200 meters.

The problem of high density is the problem of too little land per capita to begin with. Adding much floor area per capita to it, is of limited help as necessary amenities will claim space outside the building as well. In fact the effectiveness of saving land by adding more floors decreases dramatically between five to ten floors (4) . The popular belief that high-rise is the cure for high population densities, is a myth. As long as there are too many people in an area, there simply are too many people in that area, no matter what fancy way they are packed or stacked.




Photo 11. On the threshold in space and time: brand new housing meets the slum it will replace.

A fair way of grading development strategies is to look at the interaction between user and building.

Only when people contribute, upgrade and improve, the building is a success.
As long as people maintain it, the building is satisfactory.
As soon as it pauperizes, the building is unsatisfactory.
When people move out often, it is a failure.

It is therefore no surprise when inhabitants of rehabilitation projects choose to sell their condo and return to informal settlements. It is a practice often frowned upon, and a show of healthy common sense.

Notes:
(1) Mike Davis, Planet of Slums, London: Verso, 2006.
(2) Planet of Slums gives an overview of the many programs carried out throughout the world and is a useful book in that way. The downside of the book is its slash-and-burn prose. Not a single program is critiqued positively, not even the demonstrably successful ones. Although Davis presents a plausible analysis of the course of events that led to immense slum forming, he refuses to even hint at a possibility of a way out. He thus takes an easy position. Too easy.
(3) Greg Girard, Ian Lambot, City of Darkness, Life in Kowloon Walled City, Watermark Publications, 1993.
(4) Charles Correa, lecture for Urban Typhoon Dharavi Mumbai, 18th March 2008.