Natural Buildings in San Pablo

Natural Building in San Pablo, GuatemalaBy: Claire Landkamer, Tasha Nobles, Andy Rohner, Amanda Rowlee, Cameron Wardlaw

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Natural Building has been around for thousands of years and is the most efficient way of building without modern technologies. Different cultures around the world have developed their own techniques of building based on local resources, topography, and climate. Many of these societies produce decent living spaces, but without knowledge of modern day building techniques and materials, these current living spaces could be much improved. Our team plans on integrating our knowledge of modern day building techniques to produce a more efficient living space naturally.

Problem Statement:

To provide appropriate technologies for natural building techniques in developing countries utilizing local resources to help improve the standards of living. Since our class is closely tied to the community of San Pablo in Guatamala, we will focus on building a natural structure for their Guateca schoolhouse.

Our approach:

We contacted previous students that were involved with Guateca to inform ourselves about the current living conditions to figure out the different issues they experienced.

  • Issues pertaining to San Pablo Residence:
    • Warmth (Heat Retention)
    • Light
    • Energy Use
    • Technology
    • Structural Integrity
    • Cost
    • Resources
    • Location/Topography
      • Earthquakes
  • Current Materials Used:
    • Clay
    • Sand
    • Hay
    • Water
    • Corrugated Steel

The current building materials are used because of their locality. In natural building, use of local materials is critical. Because of this we will use some of the same materials they currently do, but with different design in uses of the materials to mitigate these issues.

Our research:

We found information on the climate conditions and natural materials of San Pablo, and common natural building techniques in response to the building issues stated above.

  • Current Climate Conditions that need to be considered:
    • Elevation: 9470 ft
    • Mean Min Temp: 44.4 F (7 C)
    • Mean Max Temp: 67.4 F (19.7 C)
    • Mean Relative Humidity: 84%
    • Precipitation Day in 2010: 125
    • Precipitation: 6.5 ft
    • Mean wind speed: 3 mph from east

San Pablo is within the temperate zone, which means buildings must be built with high mass walls and roofs to retain heat as much as possible. Rain occurs often in this climate zone so proper waterproofing is a critical issue. Other issues from water intrusion are mold and rot, which can diminish the structural integrity of the building very quickly.

  • Natural Materials:
    • Bamboo
    • Cob
    • Stones
    • Wood
    • Pine Needes
    • Corn after harvesting

  • Natural Building techniques:
    • Adobe
    • Straw Bale
    • Cordwood
    • Cob
    • Earthbag
    • Rammed Earth

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Our solution:

From the research, we concluded that straw bale construction is most efficient. Because straw is not readily accessible in the area, we have decided to use corn husks from the waste of harvested corn. In order to do this, we need to make bailers, which can be made of small amounts of wood and some screws. Custom building these bailers also enables us to build custom sized bales to fit the building design. These bales can be used to construct more quickly and efficiently than their current use of adobe. This also provides them to utilize their waste in a productive way.

  • Foundation: 2’x4’ trench, filled with stone/gravel to 3” above grade (ground level), 3” tar water barrier
  • Flooring: 3” stone/gravel, 3” adobe/cob
  • Walls: corn husk bales with cob exterior and interior layers
  • Roof: low-sloped, bamboo beams and joists, woven corn husk thatching layer, 6” corn husk bails, adobe, cement water barrier/corrugated metal
  • Windows: glass, plexiglass, placed in cob, double pane
  • Doors: wood/bamboo

Community Effort:

Building system can be replicated easily by locals, and will enable each individual to participate in the design aspects of their own project (co-design).

Design:

How does it compare to what’s already there?

    • Retain more heat
    • Allows for more light
    • More structurally sound
    • Decreased chances of water intrusion and water-related damage

Cost:

    • Natural and free materials: gravel, cob, adobe, corn husk, water
    • Materials to buy/import: cement, tar, bamboo, wood and screws for baler
    • Estimated total cost of imported building materials:
      • 94 lb bag Portland Cement, type I$25/cf
        volume of roof waterproofing75 cf
        (1500sf x 0.05’= 75cf)
        Transportation: 20%
        Waste Factor: 10%
        Total Cost: $2500
      • 5g Tar Waterproofing, 1.2 cf$25/1.2 cf
        Volume of Tar waterproofing
        (160lf x 2ft x .25ft=80 cf)80 cf
        Transportation: 20%
        Waste Factor: 10%
        Total Cost:$2200
      • Wood and screws for balers: Conceptual Estimate $250/baler
        Number of Balers:6
        Total Cost:$1500

Distribution:

Introducing these building techniques into the community by building a prototype can potentially influence the population. Assuming that the end product performs as expected, local residents may decide to build their own, more efficient homes with this method. Perhaps some local residents may start a business with these techniques by building for others in the community or neighboring communities.

Works Cited: