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Rethinking low-cost housing

Project designs flexible spaces, compatible with a modern lifestyle

DisseminationView of one of the houses of the project: low-cost materialsDissemination

When we speak of popular housing, we immediately imagine tiny, anonymous houses arranged in a monotonous line in some patch of ground on the outskirts of town. The survey Social Housing: Architectural Design and the Production of Components from Reforestation Wood and from Raw Earth – coordinated by professors from the Department of Architecture and Town Planning of the São Carlos Civil Engineering Department at the University Federal of São Carlos – seeks to redefine the criteria guiding the project and the construction of social housing.

The starting point was the observation of changes to the composition of family groups and in contemporary lifestyles marked by the development of domestic work, by the change to demographic profiles, by new relationships between family members and by the wide variety of family profiles. The survey questions the space provided by conventional popular housing, designed for the typical nuclear family, which has lost ground in recent decades to now forms of domestic organization. This reflection on domestic space led to a more flexible design enabling it to be adapted to circumstances.

The survey proposes large spaces that can be either integrated or separated, at the same cost as a conventional house Carried out between August 1996 and July 2000, the survey included the project and the construction of two houses on the USP campus at São Carlos. FAPESP supported it financially, through the Assistance to Young Researchers in Emerging Centers program which gave R$ 129,000 for the construction of the house and the payment of most of the grants, while the CNPq made a few scientific initiation grants. The team was made up of 12 professors, graduate and postgraduate students, as well as external consultants. Professor Marcelo Tramontano, professor Akemi Ino, both of USP – São Carlos, and professor Ioshiaqui Shimbo, of UFSCar coordinated the project.

The project was undertaken in five research areas: spatial design, structures, door and window frames, finishing and sealing. The studies and experimental production in workshops and materials laboratories – reforestation wood, raw earth, and straw, chosen for their low cost – were carried out for two years. After various tests, the materials were integrated into the technological proposals for the production of the components of the houses. The architectural design project, by Tramontano, went on at the same time. The Group organized workshops, used to publicize the results of the survey and operated as an experimental labor work site.

The survey faced certain difficulties. “The main one was management of the logistics of the works site within the university structure. Besides this, the construction labor looks down on these materials. This required much closer monitoring of the work. But in the end we trained two people during these four years, and today they construct anything we need”, says Tramontano.

Served block
The two houses have a total area of 54 square meters each. They have two main spaces: the service block – with bath and kitchen equipment – and the so-called served block with no fixed equipment where the space can be used for the living room, bedroom, or workshop. The two blocks are connected by a central area, which can be a meeting and circulation area, or it can be incorporated into one of the two blocks. “All the access to the various parts of the house takes place through this central area. You can go a room without going through any other. It has a double rise in one house and a triple one in the other and it is separated from the outside by a gate. Visitors to the houses who answered our questionnaire attributed various different uses to the central area: garage, small store, workshop, living room, or porch. The resident can modulate the domestic space as he or she chooses, adapting it to his or her requirements”, explains Tramontano.

The whole formed by the served block, the service block, and the central area is a spatial system. The two houses built are two options for arranging the system, showing the various combinations possible. These variables also imply multiple external shapes, thus avoiding the uniformity of conventional housing, conveying to the outside of the house some of the personality of its occupants.In the services block, the walls are built using two techniques. The first is the hand plastering, wattle and daub of traditional Brazilian houses, which was revised and optimized.

The framework of the walls uses pre-fabricated pine panels, instead of the bamboo and branches of the primitive technique. The panel is attached to the main structure of the house and is filled in with raw earth mixed with straw, using coast-cross grass. Adding the straw stops the wall cracking, as it happens with plain wattle and daub. After the earth has dried, gaps appear at the join between the walls and the pillars, which were sealed with a castor-oil-based resin developed by the USP’s Chemistry Institute at São Carlos. The walls’ surfacing is of latex-painted, raw earth mortar ensuring a high quality finish. The cost per square meter of this type of wall is around R$ 27, including labor.

The other technique tested is straw, much used in northern Europe as a sealant of for thermal and acoustic insulation. To adapt it to Brazilian conditions, coast-cross grass was used, with the addition of clay and water. This technique is simple and enables blocks to be pre-fabricated or single walls to be built on the spot. The blocks are given an internal finishing of earth mortar, subsequently painted, with planks on the outside. It takes a long time to produce the blocks, requiring care in drying out the grass and in transport. It costs around R$ 41 a square meter.

The walls of the served block are of wood, with a framework of pine, closed internally with wainscoting and externally with boards. The structural parts in eucalyptus were treated using the autoclave process, stopping fungi developing. Various types of thermal insulation were tested on the wooden walls: a cushion of air, expanded clay, fiber-glass blankets, and polystyrene slabs. The yield and the durability of each is being measured and can only be assessed in the long-term.

The other type of closure used is corrugate fiber-glass sheets. This material is traditionally used by residents of popular housing to cover a good deal of the unbuilt area of their portion. Translucent, the sheets cover the central areas of the houses, ensuring generous natural light. The window and door frames were tested using reforestation wood: eucalyptus and pine. The structure is made of eucalyptus beams and pillars on metal supports, fastened to a concrete foundation, enabling the houses to be built on any kind of land. The tiles are made from pressed pulp residue and bitumen. All the electrical and hydraulic installation is visible, lowering cost. The same concern guides the layout of the kitchen and bathroom: sited either alongside one another (unit 2) or one on top of the other (unit 1), the length of the piping is thus dramatically reduced.

“Unit 2 was built in 1998. Based on the lessons learnt in the construction, we revised the design of unit 1, which was built in 1999, and we reformulated certain solutions for unit 2. This feedback is part of the project”, explains Tramontano. After the conclusion of the survey, the team was divided into two groups: Nomads ( the Portuguese acronym for Study Nucleus on Housing and Lifestyles), of USP, coordinated by Tramontano, and the Abis, coordinated by professor Ino and by professor Shimbo. The Nomads focuses more on architectural projects and the Abis has a more technological bent. The two groups continue working on the houses: Nomads is studying new ways of making progress on the internal layout and the Abis is measuring the thermal insulation.

In Tramontano’s opinion, the domestic space must be thought out for the whole of the population. “To do this, we invited people of all income groups and from various regions to visit the houses. Most gave their approval to the projects. The questionnaires let us know details for various interest aspects”. Most visitors accepted mobile wooden partitions, but the part made of zinc plate was rejected out of hand by all. “Zinc has connotations of shakiness. The wood and the raw earth were resisted only by those earning from 12 to 20 minimum wages; they would only accept these materials in country or beach houses”, he says.

The project
Social Housing: Architectural Design and Production of Components in Reforestation Wood (nº 95/09716-9); Type Support for young researchers program; Coordinator Akemi Ino – UFSCar; Investment R$ 170,925 and US$ 19,000