This housing model offers several advantages relative to traditional construction methods: speed, as it only requires five days for construction; because anyone can participate in the process; and affordability, as the total cost of each house is very small in comparison to other methods and materials.
The TUM technique can be applied to various projects, as in the case of the TUM Classrooms. A typical classroom is 6x8 m and has an approximate cost of $300,000 MXN; classrooms of the same dimensions built with the TUM technique can be constructed with 60% fewer resources..
To carry out the environmental component of the project, collection centers where citizens voluntarily deposit their waste PET, paper, cardboard, glass, aluminum and TetraPak have been installed in schools. Wastes that are collected and not used for the construction of the houses are sold to recycling companies, generating additional resources for the acquisition of more material and therefore increasing the number of houses built.
To be prepared for use, the TetraPak and PET must meet certain characteristics. PET may be crushed or not; the only concern is that the bottles are clean inside and out. As for the TetraPak, it must be opened and flattened like a sheet of paper, and washed to prevent fungal growth from food waste in the container.
The TetraPak is stapled in the outer and inner faces of the wood frame to waterproof the walls, and PET bottles are placed in the middle of these two layers. Subsequently the walls are wrapped in a wire mesh and covered with a layer of cement about 1.5 cm thick.
In this way the wall’s finish is similar to that obtained from the use of prefabricated products, including superior durability due to the wood frame structure.
Sustainable construction and waste management
The relevance of the technique developed by TUM lies in the simplicity and economy of the process. At its foundation is the construction of ecological, prefabricated walls using sustainably harvested wood frames, recovered TetraPak for waterproofing, plastic (PET) bottles as insulation, and an inexpensive wire mesh and stucco surface.
Since the program’s inception in 2008 and through 2011, TUM had built 11 houses and five classrooms. At the end of 2012 there have been a total of 51 buildings: 45 homes and six classrooms, tripling in one year what had been achieved in the three previous years. This was achieved thanks to the resources that the organization obtained in 2012 to carry out its most ambitious program.