Upgrading La Esperanza - Part 4 of 4

Note: The following is a shortened version of the graduate report prepared for the Minimum Cost Housing Group (MCHG) of McGill University, Montreal. This report was written by myself, along with Cesar Gonzales, Tong Gan, Yue Li, Annalyn Maribbay and Alejandro Lopez. 


Proposals for Physical Aspects


Community Level


Community Self-Help Centre: The proposed Community Centre would be located on the current plot along street 21 and street 7. This vacant plot has large trees, which shall remain, and also an existing open shed. This is where the school was formerly located. 

The area being accessible from the main entrance to the community by primary streets makes it an ideal place for important social gatherings. Several community activities would be encouraged to be held there: 

• Education and Training: A self-help centre was located within this area, catering for the residents' needs and helping define the upgrading process. This is where education and training on the community development programs takes place such as primary health care, early childhood education, communication skills and methods, and other modalities, of training the resident community volunteers. The self-help centre has an open plan concept using the existing shed and extending it to render the place less intimidating and be able to encourage community-involvement in the whole upgrading process. The centre would use readily available materials and low mode of technology in order to keep costs down. 

• Commercial/Economic Activities: Commercial activities like mobile markets would be encouraged within this area. Home-made goods like crafts, food and agricultural produce can be sold here to augment neighbourhood income. Alternatively they could sell goods bought from nearby towns.

• Social Gathering : A plaza designed to accommodate social gatherings and major community events would be located on this area. As focal point, a traditional gazebo would be strategically located, as to represent the neighbourhood spirit which is deep-rooted in the Mexican culture. The upgrading process intends not only to enhance the physical attributes of the community but also its sense of neighbourhood and pride.

The entire Community Centre would be progressively developed ensuring that at every stage the outcome is user-controlled, managed and maintained. Simple materials that are readily available would be used to encourage a user-built product. Each phase in the upgrading process would be cost effective, commensurate to the financial capabilities of the inhabitants.

Open Spaces

The concept of developing community open spaces by promoting the "user-built and maintained" approach, would lead the upgrading process to its gradual implementation. By promoting participatory planning and design, the environment can become be culturally rich, organically evolved and more responsive to people's behavioural, economic and ecological needs.

We adopted "traditional'' patterns for the design of open spaces, which are usually small in its scale, have low-cost development, are user developed and maintained, utilise appropriate technology, and are a result of 'bottom-up' design approach. For community spaces like the plaza, where local social gatherings take place, and the market place where residents buy their daily supply, should be managed and maintained by local residents for their own use and enjoyment. Participation would usually breed self-worth and a sense of brotherhood within a community. Through participation, individuals develop useful skills that bring about self-reliance, political clout, and discourages crime and vandalism. Gateways promote an increased sense of local pride and identity. Community participation in the construction and the use of local materials that are readily available such as timber would make it cost-effective. Daily commercial activities happening on primary streets are encouraged through proposing designs with the understanding that these very same activities could generate income for community development. In enabling the approach to the community open-space upgrading process, the concept is based in progressive development and must be user-oriented.

Circulation

Considering usage hierarchy both for community open space and circulation is an important factor for the upgrading process. Understanding these classifications helps one identify which entry-level solution would be implemented, and at what cost. Progressive development of the circulation areas can be done simultaneously with that of the open spaces. Development of the circulation areas would definitely be an incremental process because of the intimate relationship between the plots along the street bordering these block of plots.


Primary Access Streets: Street classification have not evolved yet in the community of La Esperanza. No sidewalk and curbs to identify street usage giving a homogenous street structure. The upgrading approach proceeds from these street classifications: the primary access street, secondary street and purely pedestrian street. Primary streets includes 21st street and 7th street which have an existing 8 meters width. This width would be taken advantage of by giving 2 meters of plot owner along these streets to accommodate extension for commercial activities. These roads are primarily for vehicle traffic. Paving these roads would be an immediate task in the upgrading process since they are the main thoroughfares that would channel faster and easier mobilisation of the upgrading activities within the community. The strategy would be done in stages whereby the first stage will be just the levelling the rugged condition of the street and consolidating a sloped cross-section for storm water drainage. Second stage would have to enhance and define street edges by participatory landscaping engaging plot owners along the streets to be involved. In the future stage these streets are to be paved with more durable materials.

Pedestrian Streets: The existing condition of these streets are poorly located on steep slopes rendering it unsuitable for vehicular traffic and are even difficult for pedestrians. The proposal is to turn these streets into purely pedestrian streets, suitable for walking, children playing and small social gathering. The street then becomes a semi-public space where a whole range of street activities can take place. Construction of steps to help negotiate the slope by the residents is essential. Plantation can help prevent soil erosion and storm water run-off can be drained along the centre of the street. Vehicular traffic is not encouraged in these streets but the design proposal is such that in case of emergencies vehicles can access the dwellings.


Green Streets: Green streets are streets set parallel to the streets 21. The existing road conditions, with undulating, rugged, steep and narrow cross sections, shows that vehicular access through these roads would be very difficult. The upgrading proposal suggests that these streets be identified, incorporating small recreational open spaces for children to play and landscaping the edges of the streets. This design would encourage relaxed walking. Gateways would be installed at boundaries of these streets to enhance the sense of pride within the neighbourhood. These streets can be upgraded in the same pattern, in stages. The first task is to level the streets so people can walk safely. Treatment of slope would be done immediately at this stage. The final stage is the incorporation of street furniture and landscaped treatment. Finally it can be paved with durable materials such as asphalt or concrete blocks. However difficult these streets are for vehicles, the design does not impede through-traffic.

Infrastructure


Water Supply: According to the necessities of the community, one of the objectives of the upgrading plan is to provide the water supply to the whole community. The proposal is divided in different stages, following the progressive concept. The first step is to provide a pump house where water can be extracted and pumped to a tower tank that would be placed at the top of the mountain, in order to allow the necessary pressure in the pipes through use of gravity, thereafter two communal taps would be built to service the community at the entry level. Once the water is deposited in the communal taps, the second stage is to provide a main water network along the spine street, and the third stage is to expand the water network to the all streets of the community. The proposed network has been designed in such a way as to allow poor families to have access to piped water at affordable rates. Furthermore people won't have to walk long distances to fetch water from communal wells or taps.

Sanitation: Pit latrine was found the most suitable option for the proposal at the entry level, as it offers several advantages over the conventional sewerage system. The second stage is to improve this latrine into the pour-flush toilet, which require only two litters of water for flushing. Furthermore the system permits re-use of waste-water as agricultural fertiliser. For the long term plan, it is proposed that latrines be incorporated into the sewerage system to be provided by the municipal Government.


Drainage System: The drainage system proposed incorporates an open channel to be built in the centre of the streets as an entry level solution. The profile of the slopes facilitate this approach because water rain can easily run through the channel. Moreover, water from washing and cooking activities (grey waters), in the dwelling can also be collected and deposited into the channel. The second stage is the improvement of materials and construction methods of the channel, for instance the construction of the channel with bricks and mortar which would be covered with a cement layer.


Residential Level

The design of the open space in the plot is based on a module of 3.00 by 3.00 M. The maximum width allows is 6.00 M. which gives a 2.00 M. lateral set back. In these three main open spaces we propose the plantation of trees, low plants and shrubs like: Coconut, banana, papaya, palm trees, bamboo and corn; as well as slope retaining walls made of bamboo, dry stone, solid stone and boulder banks. To enclose the plot area we propose the creation of fences made of Bamboo.
Depending to the inclination of the terrain, in the front yard is proposed the creation of steps to access the dwelling. The lateral set back is thought as a porch space that can be placed in front of the streets on corners of blocks. And the back yard where all the planting of bamboo, corn and trees will be seeded, as well as flowering and vegetation.

Dwelling Level:


Construction Method 1- Bamboo: The first construction method proposed deals with indigenous materials, some of which are easy to get from the vicinity, resulting in a very low cost option. The main material, for both structure and enclosures is a type of bamboo, known as otatein the region.
The foundation proposed is built with the traditional concrete footing, which is then tied using thin beams, giving the foundation the necessary rigidity and structurally a good resistance. Within each footing is placed a steel bar of about one meter, embedded with concrete to hold the bamboo column on top. Each bamboo column must have a diameter from 10 cm. to 15 cm. of diameter. The beams must be thinner than the columns in order to fit on top. The span that holds all the load must be reinforced with a double bamboo layer, in order to create enough resistance to torsion, which is the only weak side of bamboo.
In two-story buildings the upper floor is made of several bamboo beams that are secured with screws and nuts to the main beam. Then the unrolled bamboo is placed on top, secured with nails and wire. The last step is to plaster or tile the floor. To plaster columns and beams is necessary to cover the bamboo with a wire mesh, in order to give adhesion to the bamboo's surface.
To build the walls, it is necessary to reinforce the structure with diagonal bamboo posts, then theEsterilla or unrolled bamboo is extended along the surfaces of the structure. The last process is to plaster and pain the wall with lime, or with paint, if the resources are enough. The pipes and electrical features are placed within the wall in the empty spaces between the inside and outsideesterillas.
This type of construction method is very useful for use in sloped terrain. It is here that bamboo shows its best quality: the compression resistance.

Construction Method 2 - Small Pre-Cast Components: The second option presented in this upgrading proposal is the pre-fabricated method of construction, consisting of a small-scale building component, which is the concrete block. The block whose configuration resembles a cube, with a .20 x .20 x .20 m dimension. Its shape however, can be modified according to structural application. Production of this building material could be done on the builders' yard by self-help centre trained individuals thereby keeping the production cost to the minimum.
The resident who chooses this option will have to proceed first to the self-help centre for guidance and for their needs to be quantified. Choices of how to build the new structure or how much additional space is required would be given to the resident/client. The method of construction for this particular option does not require high technology. The product could be user-built, so construction cost could be kept low. At the site, foundation is laid out first, cast on site. The concrete blocks, that are usually open on two opposite sides like a doughnut, would be placed on top of another, forming columns and beams. For sloped site conditions the flexibility of these blocks can be taken advantaged of because of the fact that the builder can actually choose the height appropriately without cutting or bending the materials. The technique would be just to add or subtract blocks , depending on the height required. Next step would be to provide the floor and roof slabs which could come in pre-fabricated form or traditionally laid out, since the system is categorised under the open-system of pre-fabricated construction. This choice depends on how much time the resident/user has and his income capacity. Wall infill could be put next, with opening for the fenestration. Incorporating the sanitation system can be done simultaneously with the wall or floor construction. Water supply and electrical supply can be installed at appropriate construction stage. The blocks can also be used for drainage as it forms a c-channel with its one side off. Productions of these blocks and its various usage does not only help to provide shelter but could it has also the capacity to provide potential for economic growth. Skills gained from the training provided for in the production of these blocks, could create jobs for some of individuals. By offering these skilled services to nearby towns could be an income-generating endeavour, helping the upgrading proposal realise its intention of sustainability.

Construction Method 3 - Conventional and Pre-Cast Concrete: The Construction Method proposed here incorporates the idea of mixing traditional building materials, familiar to local people, with pre-fabricated elements. The structural system is made of conventional reinforced concrete cast on-site, for both columns and beams, as well as for the foundation blocks. The concrete slab, used either as roof or floor slab, is made of pre-cast "T" beams which hold concrete blocks or clay bricks and are then covered with a thin layer of cement and sand mix. The necessity of scaffolding for a pre-cast beam is minimum, which helps reduce the number of wood planks required. The beams can be produced in different sizes, but to keep expenditure with costly metal molds the lowest possible it is suggested the adoption of modular construction.
The whole concept is fairly simple: the base of the construction is a method already in use by locals, the pre-cast components can be produced at the Builder's Yard by the homeowners and their families with minimum training, the assembly of the lightweight components requires few workers and can be carried out in a progressive manner. The families can start producing the components for their house on their own pace, stocking their produce until they have enough for the initial stage of construction. All the other elements that complement the building process, such as plumbing, sanitary and electrical installations, are also based on solutions already in use by locals.
The method is proposed as an open ended solution, which means that several stages of the construction can be exchanged and/or mixed with options taken from both construction method 1 and 2. This openness in inherent to the independent nature of reinforced concrete elements in relation to other building components.


Cost comparison: The three systems proposed have been studied and analyzed according to the building materials found in this region. The results found reflected each system's nature and identity. For instance the pre-cast system which is a good, fast and simple method was the one with higher cost, US$ 680.00 however it is the system that most of the people of Zihuatanejo would like to have as a temporal and definitive home. The other system studied was the block system which is more manual and better known by people in this region, got the medium price, US$ 576.75 The pre-cast and the block systems are proposed to be made in the builders yard. The Otate system, which is the most economic of the three, uses indigenous organic building materials, however in this region it still has not been used in the way it is proposed here. The simplicity and reasonably faster construction make it a good alternative as an entry level, mostly for the poorest families whose resources are very limited. The cost for this system was US$ 493.50. All three systems were analyzed and quantified based on the module of 3.00 m by 3.00 m, as shown in the tables.