Sustainable Building Solutions-Haiti
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The Senp Kay is the first structure in Haiti constructed utilizing prefabricated, tilt-up, plastic bottle filled panels and light straw-clay walls. It was designed and constructed as an innovative solution for low-tech, sustainable housing for low income communities in emergent nations. Affordable housing is an issue of huge social relevance in Haiti, and indeed globally. Two years have passed since the earthquake in 2010 and thousands of Haitians continue to be without permanent shelter. There are over 800 camp settlements with an estimated .5 million people still homeless. Inadequate standards of construction and poor quality materials were the root causes of many of the collapsed buildings and loss of life. It is extremely important that reconstruction addresses these issues, and ensures that new buildings are earthquake resistant and provide protection in the face of future seismic events as well as hurricanes. The need for permanent, affordable, safe housing is pressing.
Using Local Materials and Developing Local Industries. The Ti Kay Pay was designed to use as many in-country and local materials as possible, to build on existing labor and skill resources, and to encourage the creation of local industry. From the foundation to the roof, material and building system choices were made with these goals in mind. One enormous material resource that is largely untapped in Haiti is the rubble resulting from the collapsed buildings in the earthquake. The Ti Kay Pay design uses crushed rubble in the foundation and in the stem wall in gravel bags. The same crushed rubble is also screened for fine aggregate in the plasters. The Ti Kay team and one of its partners, the Ecological Building Network, have purchased a manually operated rubble crusher to generate that material. Alternately, the gravel bags can be filled with the crushed limestone that is commonly used as an aggregate in concrete. This material makes a weak concrete, but works exceptionally well as fill in the gravel bag system. The gravel bags are made from the ubiquitous tarps that are found throughout the earthquake affected region. Cut and sewn to the needed size by a local seamstress, damaged and otherwise unusable tarps can be turned into building material instead of becoming part of the waste stream. Straw bales are central to the Ti Kay Pay construction system. Rice straw is plentiful in Haiti, as rice is commonly grown in the broad Artibonite Valley northwest of Port-au-Prince, as well as near Les Cayes on the south peninsula. At least 80% of rice straw in Haiti goes to waste, usually burned after harvest, polluting the air in the process. Two and sometimes three rice crops are grown annually, making straw a rapidly renewable resource in Haiti. The Ti Kay Pay uses manually baled straw, for its wall system, reinforced with bamboo and covered with interior clay and exterior lime plasters. Clay is readily found throughout Haiti and a tradition of clay plaster exists. Pallet or bamboo trusses provide the roof structure, covered with commonly available and durable sheets of corrugated steel. Wood from pallets, left from the vast number of post-earthquake aid shipments, has become a new in-country resource for Haiti. Bamboo has long been native to Haiti, and a number of bamboo plantations existed before the earthquake. However, it is now widely seen that strong and fast-growing bamboo has been underutilized as a construction material in Haiti over recent decades. A campaign is underway to increase bamboo plantings and develop a bamboo industry, especially with species such as Guadua that are particularly effective as a structural material. Bamboo also has tremendous potential to help with Haiti’s staggering condition of deforestation. Cool Houses. Although the thermal insulation commonly associated with strawbale buildings is generally not needed to keep buildings warm in Haiti, the system’s excellent balance of mass and insulation moderate temperature and keep the interior space cool. A light mix of straw and clay is used as insulation above the ceiling to shield the interior space from the heat of the sun as it warms the roof during the day. The attic space is generously ventilated, and louvered transoms above doors and windows provide cross ventilation throughout the day. Culturally Appropriate and Flexible Design. BWB’s Ti Kay Pay is a culturally appropriate design derived from the Haitian Ti Kay, the common two-room plus galri (veranda) house, which is the fundamental rural and sub-urban living unit in Haiti. The design/build team has developed an understanding of Haitian vernacular building traditions with research and field observations and input from local Haitian designers. The “Galri” is especially important to the design, since much of Haitian daily living occurs outside. It provides an outdoor space protected from sun and rain and serves as a transition from the more public yard or street to the private interior rooms. The Ti Kay Pay design also lends itself to expansion. A third room in the back can be easily added, extending the shotgun floor plan. Rooms or porches with shed roofs on one or both sides can be added as well. Window locations in the design can instead accommodate doors and vice versa as the site or needs of the owner demands. The design is a blend of traditional and modern in its form and appearance, including the plaster finishes associated with the modern concrete and block buildings Haitians have come to prefer, but with a light roof that so many Haitians are returning to after countless concrete roofs collapsed in the earthquake. The system of strawbale construction developed for the Ti Kay Pay can also be applied to other house designs, or other building types as well. It is particularly suitable for use in small schools or clinics. Larger scale buildings, including two story buildings, could employ many of the systems developed for the Ti Kay Pay with proper engineering. Safe Buildings for Secure Lives.The Ti Kay Pay has been engineered to withstand earthquake forces exceeding Haiti’s January 2010 earthquake, as well as 145 mph winds from hurricanes that annually threaten Haiti. Mesh reinforced plasters encase the gravel bag foundation, vertical lengths of bamboo stiffen the walls, and steel wire tension ties diagonally brace the corner wall panels, all to resist earthquake and wind forces. Large uplift forces under the roof from hurricane winds are countered with the weight of the building itself, by strapping the roof down to the foundation. Affordability. The cost of these buildings is extremely important, and is being carefully monitored. The more affordable and the more they can compete with conventional methods of building, the more they will be utilized. Ways to simplify the building system and make its construction more efficient are constantly being explored to reduce cost, but without sacrificing safety or durability, and in fact making the building more so. Associated Building Systems. While the foundation, wall and roof systems are carefully considered and make up the building itself, associated systems are addressed as well, including: Rainwater catchment to above or below ground cistern, Direct current photovoltaic system for lighting and other low-demand electrical needs, Dehydrating or composting toilet systems, turning human waste into agricultural fertilizer, Efficient cooking systems, such as rocket stoves or solar ovens will be promoted. (Text by Martin Hammer: Co-Director Builders Without Borders)