The experience of San José de Chirica showed that invasion settlements are neither unprepared nor spontaneous processes. Instead, these developments followed certain settlement patterns which were defined by the social, political and economic context in which they occur. These settlement patterns became the strategy of the low-income population to obtain land and housing. Some of these patterns were acquired from formal planned developments, and adopted to the particular characteristics of the site and the settlers. Other settlement patterns were defined by the settlers based on their own capacities and requirements. Both types of settlement patterns fit the process of incremental development that is typical of informal low-income developments.
In San José de Chirica, the street, block and plot layouts were similar to those existing in planned developments. However, the use of these formal patterns was flexible. The settlers adapted these patterns to their particular needs, the existing plots and the topography of the site. For instance, the grid-iron street pattern was laid out as settlers were arriving and the settlement was growing. Where required, the grid-iron scheme was modified by surrounding the existing big plots, and integrating the rain ditches in the scheme as a street. Since resources were scarce, streets remained unpaved until official support was obtained. Not all the streets were paved at once, priority for paving was given to the most important settlement streets.
The use of planned settlement layouts gave the settlers the idea of a more "organized" development, which would ensure the official recognition of the barrio. In addition, the use of conventional planned layouts would ease the provision of services and prevent damages to the plot and the dwelling in case of the implementation of the upgrading program.
In spite of its initial dispersed appearance, the settlement rapidly began a process of intensification. By 1980, two years after the invasion began, 91% ofthe site (38.6 Ha) was allocated to newcomer families. By 1983, almost all the site (98%) was occupied, and families continued arriving. Some plots were subdivided, while others were occupied by more than one household. By 1987, all the site was occupied: approximately 80% of this area was used for private purposes, either housing, commercial or community activities, 17% was used for streets and sidewalks, and 3% was used for public uses, specifically the primary school. At that time, more plots were subdivided or occupied by more than one dwelling. More than 90% of the families had built or began to build a second dwelling using more durable materials. By 1991, a third dwelling was built or was being built also using durable materials in some plots. This intensification process is likely to continue since there are still many empty areas in most of the plots. As a result, the settlement would progressively achieve similar densities to those of planned developments for comparable income groups. This dynamic settlement process is evidence of the ability of low-income groups to solve their housing needs, even though some facilities and infrastructure were initially lacking.
The development of San José was not conditioned by the provision of infrastructure and services. It rather seems that services were provided as the settlement was developing and consolidating. People accepted the initial rudimentary conditions of the settlement in order to have access to land and housing.
The provision of infrastructure and services in San José showed how an informal settlement obtained services from the official formal system. Some services were obtained through negotiations. The materials were provided by official agencies, and labour was provided by barrio inhabitants. Some other services were obtained through social and political pressure. The aso-vecinos directed the petitions for those aspects that they considered more important. For instance, street paving was not a priority. Instead, other requests were made, such as adequate water and electricity provision, construction of the school, medical facilities and public transportation.
In San José, there was a practical sense in the strategy for street and plot definition. The leader, who acted as a land developer, did not invest in preliminary infrastructure before the people arrived. Instead, the existing street infrastructure in the industrial parcelling was used as the initial access to the settlement. As people were arriving, the land was allocated. The clearing and levelling of the site was done by people themselves.
The grid-iron pattern of streets was adapted to the progressive development of the settlement. This street pattern also became a strategy to guarantee the acceptance of the barrio by local government and official agencies. This pattern was also based on other barrios' experience with official upgrading programs, in which some plots and dwellings were affected when streets were re-aligned. It ensured that user's investments (i.e., plot and dwelling) would be minimally affected during the upgrading process. Besides that, the grid-iron pattern was a simple scheme and was rooted in the cultural tradition of old colonial towns. Most barrio members were familiar with the spatial organization that the grid-iron pattern of streets and blocks provided.
Initially, land acquisition was one of the most important goals for the people of the barrio. In San José, settlers occupied as much land as possible. Plot areas were larger than those immediately required by settlers for housing purposes. At initial stages of development, less than 10% of the plot area was being used. These empty areas were subdivided or used to build the more permanent dwelling or an additional one. In 1991, the average occupied plot area in San José was 20%. Also, when streets were aligned, areas between the plot fences and the new street border were integrated into the plot area. Having extra-land supported housing growth and improvement, and its monetary commercial value represented a financial security for the household. Land became the family's patrimony. Even in an unplanned and illegal settlement, land was a commodity with a profitable exchange value.
The commercial exchange value of plots influenced the housing patterns regarding the location of dwellings on plots. By locating the first dwelling closeto one of the sides of the plot, the settler could eventually subdivide the plot and obtain one plot with a layout similar to the former one. This plot, then, could be sold, rented, given to someone else or used for other purposes.
In San José, plot sizes varied widely during the initial stages. Differences in plot sizes can be attributed to the fact that the process was in the invasion leader's hands. Partisanship and friendships influenced some of the decisions. Differences in sizes were also the result of the need for more plots because of the increasing demand. Early allocated plots were larger than those allocated later. By 1991, the average plot area in San José was 652.8 m2, which is larger than the official agency's proposed size for low-income housing developments. The housing pattern in San José de Chirica is the result of a defined attitude towards housing. It responds to the constraints and preferences of the people living in informal settlements. The pattern of dwelling growth is the balance between priorities, needs and available resources of the users at every stage of the development. The pattern of dwelling growth is adapted to the vulnerable economic stability, characteristic of low-income populations.
Building a more durable and permanent dwelling could take years. However, the idea of this new dwelling is always present, as is the provisional character of the first shack. Since resources may fail at any time, nothing is discarded in advance. The first dwelling is not removed and the building process is organized in such a way that the functioning of the household is not interrupted, while the dwelling is being improved. It can be stopped at any time to re-direct resources to another priority of the household. The simultaneous use of new and old structures complementing one another is one example of how the people managed the scarce resources. The co-existence of old and new dwellings also reveals that good-quality housing is not a priority for all users, though it is a goal. This housing pattern is possible because of the characteristic context of unplanned settlements where no minimum standards of housing are required.
In terms of dwelling area, the average of San José dwellings variedwidely, and it was larger than the average area of dwellings in formally planned developments. In addition, the diversity of dwelling area sizes in the former is greater than those in the latter. The diversity of barrio dwelling sizes is evidence of the different spatial requirements and economic capacities of barrio inhabitants that planned settlements are unable to meet.
In terms of population, the average population per dwelling in San José is similar to the average for the rest of the city. However, considering the population per plot, the average in San José is higher since there are plots with more than one household. There are more people sharing space, resources, facilities, investments, efforts and labour in one plot, which is a survival mechanism of low-income populations.
The existence of many households and the variable population in plots also influenced the housing pattern related to the building process of the dwelling and its location in the plot. The first dwellings are usually located in such a way as to allow either the addition of rooms to the existing structure or the building of a new one. Old structures of the dwelling are maintained and provisionally given to a relative or a friend; rarely are they rented. This provisional accommodation represents the only affordable option for most poor migrants to start a living in the city, since no alternative housing is sufficiently provided to them. In turn, this new member usually contributes to the household expenses and work, including the building of the more permanent dwelling.
The existence of setbacks in San José is an acquired pattern from planned settlements. Front setbacks are used as a protection zone while streets are not completely laid out, and as a buffer zone between the public area, the street, and the private area, the dwelling. This front setback is also used for the dwelling extensions, such as the porch or a small shop.
Lateral setbacks are left to obtain some level of privacy from neighbours. They are used as garages, playgrounds for children and other activities. These lateral setbacks are also useful during the construction process. The separationof common party walls means that neighbouring structures are protected from possible damages during demolition. It also ensures natural light and cross-ventilation for all the rooms in the dwelling, which are indispensable to regulate the humid and warm environment prevailing in the region. Lateral setbacks are also a strategy to manage the land in order to have available space in the plot either to subdivide it or to build an additional dwelling. However, some lateral setbacks in the sample would hardly allow for the building of a dwelling or the subdivision of the plot, considering the existing building and housing standards in the settlement. In some cases, this area is not efficiently used.
The area of the backyards in San José is usually very large since dwellings are almost always located in the front part of the plot. It is occupied by diverse structures that compose the total dwelling area. It usually becomes an active living area that complements the spatial shortages of the dwelling. Many household activities are performed in backyards under the shade of the trees people planted. As was the case in lateral setbacks, extensions of backyards were not often used and looked abandoned. However, considering the continuous process of housing, it is likely to assume that these areas would be eventually used to extend the dwelling or to build a new one, to set up a small business, to build rental accommodations and the like, as observed in older low-income settlements in the same city.
The use of formal patterns in a flexible way was possible within the illegal context of a invasion settlement, in which no zoning and building regulations were enforced. The cultural, social and economic needs of the poor were satisfied because of the flexible settlement patterns. This flexibility also made possible the existence of additional income-generating activities, as well as other additional structures that supported the household life and, therefore, the improvement of the dwelling.