Structural Bamboo Building Codes

Technology|Architecture + Design

ISSN: 2475-1448 (Print) 2475-143X (Online) Journal homepage: https://www.tandfonline.com/loi/utad20

Structural Bamboo Building Codes: Catalysts for Industry, Research, and Construction Technology David Witte (Independent Scholar) To cite this article: David Witte (Independent Scholar) (2019) Structural Bamboo Building Codes: Catalysts for Industry, Research, and Construction Technology, Technology|Architecture + Design, 3:1, 50-64, DOI: 10.1080/24751448.2019.1571824 To link to this article: https://doi.org/10.1080/24751448.2019.1571824

Published online: 26 Mar 2019.

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Structural Bamboo Building Codes

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David Witte Independent Scholar

Structural Bamboo Building Codes: Catalysts for Industry, Research, and Construction Technology

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On April 16, 2016, a magnitude 7.8 earthquake destroyed over 35,000 homes along the Pacific coast of Ecuador, leaving more than 140,000 people without permanent housing. However, bamboo houses proved resilient to the seismic forces, prompting a reevaluation of the material and the creation of an Ecuadorian bamboo building code. Public, private, and academic initiatives are addressing industry challenges and developing improved bamboo construction methods that are rebranding the stigmatized material. This research documents improvements to the bamboo supply chain in Peru and Ecuador through interviews conducted with architects, engineers, and agroforestry experts across the region. The results highlight hybridized solutions that are propelling the industry toward standardizing its practices and scaling structural bamboo housing from a disaster reconstruction strategy toward mainstream use across South America.

Structural Bamboo Building Codes

90%

Introduction Population growth and urban migration have drastically affected urban development in Low and Middle-Income Countries (LMICs) around the world (Figure 2). The need for affordable housing is widespread and well-documented. For instance, the 2003 UN-Habitat Global Report on Human Settlements predicts the number of people living in “slums” will double from 1 billion in 2009 to 2 billion people by 2030. 3 One of the greatest challenges facing humanity is the need to provide resilient and affordable housing solutions to increasingly urban populations around the world. Public and private sectors struggle to provide housing for existing and migrating families alike, and an informal building sector has grown to fill the demand.

While informal settlements in LMICs are fulfilling a pressing need, the prevalent multistory, under-reinforced masonry housing unfortunately increases vulnerabilities to natural disasters, specifically earthquakes.4 The vulnerability of LMIC built environments was exemplified by the Haitian earthquake of 2010, where an estimated 250,000 people died, an additional 300,000 were injured, and 5 million people were ultimately displaced.5

80%

70%

60%

50%

40%

30%

20%

Population in Billions

10%

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Low and Middle Income Countries

High Income Countries

v Figure 1 (Previous page). Ecuadorian National Housing Ministry: 165 duplex units in La Chorrera, Ecuador, November 2017. r Figure 2. (top) Urbanization of countries by income, 1960–2017. (bottom) Population growth, 1960–2017. (Credit: The World Bank. World Development Indicators. 2018. http://data.worldbank.org/data-catalog/ world-development-indicators, redrawn by author) 1,2

Building Back Better The reconstruction phase after a disaster is an opportunity to rebuild with higher quality, improve the resilience of the built environment, and reduce the conditions that led to the initial catastrophe. After a 1999 earthquake in Colombia, an assessment found that 90% of the casualties occurred in non-bamboo homes, prompting a study by the Association of Structural Engineers in Colombia (AIS) to further test the mechanical properties of the local bamboo, Guadúa angustifolia.6 This gigantic bamboo species has been used for structural elements in housing across the region for centuries, but without a building code.

In 2002, after further testing and research, the Colombian government published the structural properties of the local bamboo and codified its use for construction in one- to two-story buildings. A similar series of events—destructive earthquakes, reassessing the value of bamboo housing, and additional research—occurred in Peru and Ecuador,7 prompting the further consideration of bamboo housing, with the result that those governments also passed legislation in 2012 and 2017, respectively (Figure 3).

As more countries codify structural bamboo elements, bamboo building technologies will evolve, allowing global collaboration to push the industry forward. A crucial threshold was passed in 2004 when the International Organization for Standards (ISO) published basic design guidance for wholeculm construction (ISO 22156).9 Additional standards were passed in September 2018 with ISO 19624:2018, “detailing the grading procedures for visually and mechanically sorting bamboo poles for structural applications.”10 A Bamboo Revolution Following the legalization of structural bamboo housing in the northwestern region of South America, the bamboo industry is experiencing renewed growth and investment. Structural-grade

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58,000 homes destroyed Over 500 deaths

Ecuador

35,000 homes destroyed Over 670 deaths

Colombia

NSR-10

r Figure 3. Correlation of natural disasters, housing crises, and codification of structural bamboo building codes in South America.

Public, private, and academic initiatives are addressing the challenges of the promotion and adoption of bamboo construction, demonstrating a collective recognition of an untapped natural resource across the region. Finally, the essay concludes by identifying potential applications of bamboo as a rapidly renewable and ecological building material.

Traditional Use Archeological remains indicate bamboo has been used for housing in the Ecuadorian region for thousands of years.11 The traditional use of bamboo housing along active seismic zones may correlate with these structures performing well in earthquakes. In addition to a high strength-to-weight ratio and a relatively light structural framework, vernacular construction connections are ductile, dissipating energy and transferring fewer lateral forces to structural members in seismic events.12 Bamboo stalks (called “culms”) are processed according to structural use. Whole culms are typically utilized as primary structural members for vertical and horizontal gravity systems and as bracing against lateral loads. Bamboo culms used as veneer materials (boards, screens, mats) are split vertically into several strips or split once and spread flat to create bamboo boards.

E100 Bambú

Ecuador

NEC-SE-Guadua

The traditional construction technique used in Peru, Colombia and Ecuador is called bahareque. Bahareque wall assemblies utilize whole culm stud construction covered with bamboo slats (Figure 4 left), bamboo board (Figure 4 middle), and are protected with a mud or concrete render (Figure 4 right).13 Covering the bamboo drastically increases the material’s lifespan, as it protects the material from UV degradation and moisture saturation while also improving the fire resistance of the assembly.

Bamboo Housing and Urban Development Many rural families migrating to urban centers can struggle to find affordable housing and settle on unused or unstable municipal land (Figure 5 left).14 Given the growth rate and lightweight properties of bamboo, its utilization is an affordable and practical solution for quickly erecting housing on unclaimed land. Single-story bamboo homes are frequently used in low-income settlements, providing housing for hundreds of thousands of people in South America.15 While informal settlements often begin with simple bamboo shelters, they are frequently replaced by multistory brick homes when economic means permit.16 As communities develop, houses are in a constant state of construction, evidenced by exposed steel reinforcing rods from tops of columns, as funds are saved for the next phase of building (Figure 5 right).

This process of incremental home improvement is a common strategy in low-income communities worldwide and can take 15–25 years for construction to be completed.17 Challenges Bamboo Stigma The strongest challenge facing the bamboo industry is that of overcoming a negative public image. The low-cost, prefabricated, bamboo and wood residences populating low-income communities are largely to blame for bamboo’s association with impermanence, as they decay rapidly due to improper construction techniques. Families with limited means often use the simplest bahareque technique of this temporary housing system, meaning the walls receive minimal protection from meteorological elements, increasing rot, and fungal attack.18 As an organic material, the performance and status of bamboo are judged against the performance of industrialized building materials. Brick, concrete, and steel are often referred to as “noble materials,” exemplifying modernity, safety, and low

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bamboo has the potential to significantly improve the safety and resilience of the low-income housing market. But before the industry becomes mainstream, it must resolve several challenges. Design solutions must address the cultural, technical, and economic obstacles that have so far inhibited bamboo’s acceptance as a desirable material for permanent housing.

This research evaluates the development of the structural bamboo building industry in Peru and Ecuador through on-site interviewing of professionals involved in the testing, code writing, and promotion of the market. Overall, the research questions framed for this investigation are: 1. What initiatives are improving the structural bamboo housing market in Peru and Ecuador?

2. What catalysts can accelerate the cultural acceptance of and increase the structural use of bamboo in the informal building sector?

Perú

2017

2010

Colombia

Sec. E: One & Two Stories Plastered Bahareque

2012

2002

Building Code

Perú 2007

45,000 homes destroyed Over 1,180 deaths

2016

Colombia 1999

Seismic Event

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r Figure 4. (left) Fully exposed to elements, untreated, and in contact with the ground. Lifespan: six months to four years. (middle) Lifted off the ground and treated with boron salt for termite protection. Lifespan: up to fifteen years. (right) Protected from sun and water and treated with boron salt. Lifespan: thirty years or more.

r

Figure 5. (left) Informal settlement in Puente Piedra, Lima, Peru, August 2017. (right) Incremental home expansion, Esmeraldas, Ecuador, October 2017.

r

Figure 6. Bamboo plantation, Los Bancos, Ecuador, December 2017.

r Figure 7. Panelized low-income housing next to main masonry home, Esmeraldas, Ecuador, November 2017.

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maintenance when compared against bamboo.19 Those promoting the use of structurally mature and treated bamboo find it difficult to convince people that bamboo can last over 100 years when sufficiently protected.

In addition to perceptions of impermanence, bamboo housing is culturally associated with rural and urban poverty. The stigma of poverty is deeply engrained in the public perception of the material, resulting in the epithet of “the poor man’s timber.” While bamboo’s cost is one of its strengths, the slowness of adoption by middle- and high-income residents has damaged the maturation of the material’s public image.

Construction Challenges Confined masonry construction is a simple building technique that allows for incremental construction techniques.

Multistory bamboo construction, on the other hand, requires specialist craftsmen to cut unique joints used to connect one cylindrical culm to another. The inability to incrementally upgrade multistory bamboo housing such that it can be constructed by inexperienced builders greatly inhibits the selection of structural bamboo in dense urban settlements.

Furthermore, there are not enough architects, engineers, and contractors in Peru and Ecuador who understand how to properly design or build with bamboo using the Norma Técnica: E-100 Bambú (Technical Standard E-100 Bamboo) and NEC-SE-Guadúa building codes, which ultimately limits industry growth.

The challenges of material stigma, supply chain issues, and lack of professional knowledge about structural bamboo material and methods has so far yielded an industry with low demand compared to construction systems with developed supply chains and global economies. 21 A Growing Market While the market for structurally treated bamboo struggles, the informal building sector keeps the overall bamboo building

industry thriving. However, Hogar de Cristo, an Ecuadorian hous­ing organization that delivers high performance prefabricated affordable housing, utilizes around 200,000 culms/year. 22 Despite this demand, existing low-cost bamboo shelters are replaced with multistory homes constructed of materials that increase vulnerabilities to natural disasters (Figure 7).

A similar demand for structural bamboo exists within three rebuilding campaigns that followed the 2016 Ecuadorian earthquake (Figure 3). Together, these campaigns utilized almost 60,000 culms of treated, structurally mature bamboo.

Each campaign was either state sponsored or funded by relief aid, prompting questions of how structural bamboo housing can be advanced in the informal sector.

For bamboo to be used as a structural component in lowincome, urban conditions across Latin America, solutions need to capitalize upon bamboo’s unique combination of physical and economic strengths, while also responding to the prevailing dynamics of informal building that enable incremental construction.

Methodology There is an increasing amount of literature on bamboo construction, including Columbian architect Oscar Hidalgo Lopez’s Bamboo: The Gift of the Gods, an invaluable book that gives a holistic perspective and comprehensive survey on the historical development of structural bamboo housing. White papers and reports produced by the International Network of Bamboo and Rattan (INBAR) also document and distribute the current body of knowledge of bamboo design strategies and construction methods.23 Literature review alone, however, insufficiently captures the design innovations currently being developed at universities through the international collaborations that resulted in three bamboo building codes. Current literature also does not yet capture the new means and methods that are modernizing bamboo construction strategies. Field research was conducted to observe the advancement of bamboo practices occurring across Ecuador and Peru. This field research methodology consists of two techniques: Site Visits Traveling to disaster reconstruction projects using the NECSE-Guadúa building code allowed for the photographic documentation of various structural configurations, joinery details, and construction delivery methods being implemented across Ecuador. The photographs were categorized according various project characteristics: traditional vs. modern building details, pure bamboo vs. hybridized structural systems, temporary vs. permanent housing, residential vs. commercial, coastal vs. mountain climate, and single level vs. multistory. These classifications were used to extrapolate trends and to gather visual evidence for validating statements made by interviewees.

The initial ten projects were selected based on ease of public access, availability of the architect/contractor, and their willingness to accompany the researcher to their built work. While the focus of the research was on bamboo housing, many building types were visited, including restaurants, hotels, bamboo treatment

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Supply Chain Management There is a logistical bottleneck for structurally mature culms.

Guadúa bamboo reaches its full height at six months and over a span of five years the plant wall gains structural maturity (Figure 6). Unfortunately, farmers are often paid based on culm diameter, leaving little incentive to wait for culms to mature.

The result is a market filled with inferior “green” culms, bamboos that have not reached their full structural potential.

Additionally, there is a lack of treatment facilities for processing culms to protect them from termites and other insects.

A common strategy is to soak culms in a tank of water with a 6% borax or boric acid solution. After three days, the culm reaches saturation and is then removed and drained, allowing the nontoxic solution to be reused for additional culms.

The culm must then be dried to a moisture content matching the local climate. 20 Culms are processed on a per project basis, which results in an inefficient use of chemicals and labor, elevates material costs up to six times the price of green culms, and introduces potential delays in construction projects due to the lengthy preservation process.

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Table 1. Participants Interviewed

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Participant

Location Interviewed

Date Interviewed

Organization

Specialty/Title

1

Lima, Peru

10/2/17

San Martin de Porres University, Institute of Housing, Urbanism and Construction

Architect, Professor and Manager of University Projects

2

Lima, Peru

10/2/17

San Martin de Porres University, Institute of Housing, Urbanism and Construction

Architect, Professor and Manager of University Projects

3

Pisco, Peru

10/6/17

Self-Employed

Head Contractor, Specializes in bamboo construction

4

Piura, Peru

10/10/17

Office of Housing, Construction, and Sanitation

Architect, Regional Housing and Urban Planning, Northern Peru

5

Piura, Peru

10/10/17

Progreso: fortaleciendo organizaciones (strengthening organizations)

Forestry Engineer, Expert in Bamboo Planting and propegation

6

Quito, Ecuador

10/16/17

International Network of Bamboo and Rattan (INBAR)

Regional Coordinator, Latin America

7

Quito, Ecuador

10/18/17

Sectoral Technical Table of Bamboo, Ecuador

Architect

8

Santo Domingo, Ecuador

10/21/17

Technical University of Pereira, Colombia

Director of the Regional Center for Cleaner Production of the Coffee Region

9

Santo Domingo, Ecuador

11/3/17

InnoBambú

Design/Build Contractor, trained in Bamboo Building

10

Santo Domingo, Ecuador

11/3/17

Self

Architect

11

Manta, Ecuador

11/15/17

Laica University “Eloy Alfaro” of Manabí, Ecuador (ULEAM)

Rector of University ULEAM, Architect

12

Quito, Ecuador

11/18/17

CAEMBA - Emergency Bamboo Homes

Founder of CAEMBA, Emergency Bamboo Homes

13

Guayaquil, Ecuador

11/29/17

Catholic University of Guayaquil

Director of the Ecomateriales Academic and Research Unit

14

Ayampe, Ecuador

12/1/17

Self-Employed

Developer

15

San Miguel de los Bancos, Ecuador

12/11/17

AllpaBambu

Preservation/Growth of bamboo and expert of bamboo housing

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plants, even places of worship (Figure 8). The network of bambuseros (those who work with bamboo) were extremely inviting and helpful in conducting site visits. The participant and project pool grew through recommendations during planned site visits, leading to an additional sixty bamboo projects being documented.

Bambusero networking continued through attending the Premio Sacha Awards (an awards program for sustainable agroforesty and buildings), its corresponding conferences, and construction workshop. 24

Results Interviews with industry experts, contractors, architects, and other stakeholders such as low-income families and government officials, enabled the research to build a model of the structuralbamboo ecosystem found to be serving the specific geographic region of Peru, Ecuador and Colombia. 25 The participants noted improved efficiency across the supply chain and increasing demand for code-compliant, legal bamboo buildings. This development is happening thanks to initiatives across public, private, and academic sectors addressing the afore-mentioned challenges that have historically prohibited the growth of the bamboo industry (Table 2). The following research is organized sequentially according to material value chain, highlighting the importance

of initiatives relating to growth, treatment/storage, design/construction and industry innovations.

Reliable Raw Material The bamboo supply chain begins at the plantation with the propagation, growth, and harvest of the raw material.

Participants described access to quality raw material as being a fundamental issue with the current industry. Initiatives addressing sourcing issues are being led by organizations like Progreso, a Peruvian nonprofit organization that has been training plantation owners to manage groves since 2011 (Figure 9). An agroforestry specialist explains the significance of this training: “When we started silvicultural management, it was a very important point for us, because the producers did not know when the cane reached its grade of optimal maturity. This was the same with the intermediaries and the final consumer. So, there was a misunderstanding along the whole chain.”

The growth cycle and plant development of bamboo is one of the fastest in the world: Guadúa culms can grow up to 8 inches a day and reach a full height of 20 to 30 meters (65–98 feet) in just six months. 26 While culms reach their full height at six months, the wall thickness of the plant takes between four and five years to fully mature and maximize its structural capability.

In addition to rapid growth, this species of bamboo grows in dense clumps, with a density between 3,000 to 8,000 culms per hectare. 27 New culms sprout each year, so organizations like Progreso teach proper bamboo management to plantation owners, explaining that harvesting over 50% of one plant’s culms could adversely affect overall plantation yield.

By training farmers, facilitating the creation of cooperatives, and connecting these rural families directly to regional treatment centers, Progreso is one regional example of how reliable networks have formed and improved the availability of structurally mature culms.

Affordable Treated Culms Year-Round The participants found that increased investment in the bamboo supply chain signals an expanding future for the industry.

A premier example is found in Santo Domingo de los Tsáchilas, Ecuador, where the regional government has invested in a large-scale bamboo center, the Centro de Acopio, Artesanal y Finca Demostrativa de la Caña Guadúa (Guadúa Storage, Craft and Demonstration Center). The center offers trainings on bamboo propagation as well as craft/furniture building workshops and operates as a regional treatment warehouse for treated bamboo culms.

Rural farmers struggle to maintain a constant demand for culms and cannot affordably produce treated poles in small batches. The regional treatment and storage facility create a new type of buyer, one who can buy culms in large quantities when extraction is cheap. There is an economy of scale and efficiency available through recycling the chemical solution through multiple batches (Figure 10).

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In-person Interviews A diverse set of individuals were interviewed, many of whom have worked for decades to develop the bamboo industry. This technique identifies frontline perspectives of the challenges and insights about their solutions, capturing qualities about the industry that are not obtainable otherwise.

In order to conduct research involving human subjects, the author’s university required approval from its Institutional Review Board (IRB), which reviewed the questions and research methodology in order to protect participants. The following research was granted exempt status, permitting the research without additional US Federal human subjects’ regulations. The University deemed the research cursory and therefore was exempt of a complete IRB review.

The author conducted in-person interviews in Spanish with fifteen participants, each typically lasting between forty-five minutes and one hour. For each interview, video and audio were recorded for future translation and analysis. Of the fifteen study participants, five were practicing in Peru and ten in Ecuador. The specializations and expertise of the interview participants are listed in Table 1. Interviews gathered participant’s experiences on the benefits and challenges of working with bamboo and their observations of developing trends in the industry, as well as their knowledge of the market within the formal and informal building sectors. Interview responses were analyzed, allowing the researcher to identify common themes and observations by this group of professionals.

Visiting structural bamboo projects and interviewing industry experts generated access to regional expertise across the material value chain, beginning with bamboo propagation and finishing with bamboo construction. Each engineer, architect, code writer, and contractor interviewed was able to volunteer detailed information about the challenges they experienced.

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Table 2. Bamboo Supply Chain Challenges

Challenges

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Initiatives

Raw Materials

Treated Culms

Stockpile

Premature harvest yields low-strength material Intermediary clear cutting causes early plant death

Lack of understanding contributes to low demand High chemical cost means low profit margin

Lack of treated structural cane causes high lead time and cost A low demand suggests an inefficient and costly supply chain

Unstable market leads to farmers switching to other cash crops

Without standardization the quality of product is unknown

Training campaign allows for higher quality raw material

Educational campaigns promote treatment as best practice

Registration of plantations requires improved management Guarantee of structural quality adds to business security

Rebranding the Structural Bamboo Building Industry Architects and contractors are modernizing the aesthetic of bamboo buildings, introducing shifts to legacy associations with bamboo buildings. With the traditional bahareque technique, builders coat bamboo slats and boards with a mixture of mud, manure, and straw (similar to a wattle and daub).

Today, builders apply concrete with admixtures to plastic lath netting that improves adhesion of the slurry to the bamboo boards (Figure 11). These designs project a modern aesthetic that could prompt a reevaluation of the material for future design applications.

Public Sector Promotion The public sector is also participating in the rebranding campaign, shifting the paradigm from a material of poverty to a sustainably valued high-performance material. 28 In 2013, one year after the Peruvian bamboo building code was published, the Peruvian Ministry of Housing launched Construye para Crecer

Material Performance Poor detailing exacerbates plant’s organic vulnerabilities Low quality raw material results in short lifespan Temporary-use buildings reinforces negative image

Post-emergency bamboo construction leads to increased material demand Large-scale Public Projects treatment allows for utilizing building higher profit margins code creates demand for treated culms Improved market Building codes promotes additional standardize supply to meet the treatment demand requirements

This treatment center, located at the center of the country, will ultimately provide structurally reliable and chemically protected bamboo culms at an affordable price year-round. This is a critical accomplishment for stabilizing and expanding the supply for the bamboo building sector.

Design + Construction Lack of trained architects means poorly designed and detailed homes Lack of trained contractors increased the cost of skilled labor

Bamboo building courses increase number of qualified designers

Correctly detailed buildings leads to longevity

Projects built to code increases demand for trained workforce

Engineered bamboo products increases material performance

Bamboo construction increases dissemination of correct building techniques

Bamboo buildings that perform well improves material image

(Build for Growth), 29 an annual competition for eco-friendly building designs. The bank of vetted designs is available to anyone interested in using bamboo to build regionally appropriate houses.

Government bamboo housing developments are also supporting developments of two-story bamboo housing designs. Stateimplemented bamboo projects increase the demand for treated structurally mature culms, and their large construction crews are trained on how to build using the new code. The development La Chorrera (Figure 1) contains 165 duplex residences and required approximately 38,000 poles. Large projects built to code enhance the public perception of bamboo housing, as they demonstrate that culms can be used structurally, are long-lasting, and can address the desire for a multistory home.

Private Sector: Entrepreneur Contractors One of the interviewees, a contractor, was trained in bamboo construction after the 2009 Peruvian earthquake. Since then, he has been working in the field; he trained his six-person crew to build using the E-100 Peruvian code and often leads workshops across the country. To further facilitate organic dissemination among trade workers, manuals with step-by-step visual instructions with diagrams and photographs were developed and distributed through these workshops.30

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v Figure 8. Yann Barnet and Faouzi Jabrane, Lomas del Pino Restaurant, Chancay, Perú, 2015.

Academic Sector: University Research Universities across Perú and Ecuador have dedicated faculty and applied researchers who have developed professional careers advancing bamboo building technologies. 32 Architecture students from these universities are learning about bamboo building in a new political legislative environment that supports construction with bamboo. At the Universidad San Martin de Porres (USMP), design/build workshops teaching design and the means and methods of “alternative” materials have been offered nine times since 2008. 33

This next generation of architects will bring fresh perspectives to the design community at large, challenging legacy notions of how materials shape modern housing.

Scholars and industry experts from around the world also share research, studies, and initiatives at international conferences and bamboo trainings across the region, which also strengthen the network of professionals working toward a sustainable future. One example is the RED SIBGUADUA Symposium, an annual conference in Colombia for exchanging the latest advances in bamboo cultivation, legislation, and standardization. 34 Universities also contribute toward the development of industrialized bamboo systems. Yann Barnett and Faouzi Jbrane, two professors at USMP in Lima, Peru, have designed a patented connector that will make bamboo construction accessible to more people (Figure 12). As they described: “We started with the premise, in what manner can we as experts and architects develop a type of union that doesn’t require a qualified workforce to join structural components? The piece we are developing addresses the challenge of creating unions for bamboo members in tension…how to grab the fibers without breaking them when applying tensional forces [to the culm].”

The invention utilizes rough, teeth-like components that grip the inside of the culm wall when in tension and an external metal ring that restricts splitting of the culm. The mechanism also allows a culm to terminate in a threaded rod, prompting a hybridized structural system of bamboo and metal components.

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Another resource utilized by contractors is the code itself.

The codes describe modernized means and methods to integrate contemporary building techniques that can strengthen bamboo’s performance. For example, culms can be mechanically connected with hooked and threaded rods and nuts, and the transverse compressive capacity of hollow nodes are increased by filling the culm cavities with concrete. 31 Contractors are also developing new tools to build quickly and efficiently to code. The unique, artisan crafted joints that increase the time and cost of bamboo construction have been circumvented by utilizing precise power tools. For example, an accurate cylinder-to-cylinder cut can be quickly repeated with a jig and a custom-made hole saw.

This contractor and others like him are important pieces of the bamboo puzzle; they teach others to build to code and disseminate more efficient means and methods, resulting in structures with decades (rather than years) of useful life. As the number of contractors with this knowledge grows, the challenge of limited skilled labor diminishes.

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Structural Bamboo Building Codes

r Figure 9. Painting bamboo culms, a forestry management strategy to track culm age.

r Figure 10. Regional treatment plant under construction. Large tanks are used to soak six-meter (19.7 ft.) and 12-meter (39.4 ft.) culms in a salt solution, Santo Domingo, Ecuador, November 2017.

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Case Studies After the 2016 Ecuadorian earthquake, bamboo filled a pressing need, providing temporary and permanent housing to thousands of homeless inhabitants. Dozens of prototype shelters were built to demonstrate the economic viability of rebuilding with bamboo at scale. Prefabrication, constructing multiple homes in series, and developing industrialized connections allowed these housing designs to be constructed faster and cheaper than with traditional means and methods (Figure 13, Table 3).

The density of bamboo growth and its rapid regeneration are two reasons for the plant material’s low cost when compared to wood or industrialized materials. One study calculates that 700 hectares (2.7 square miles) of Guadúa angustifolia provides enough bamboo to build 10,000 single family houses, yet to build the equivalent number of houses out of timber would consume 6,000 hectares (23.2 square miles) of indigenous forest (Figure 14). 36 Public, private, and academic initiatives have addressed many of the challenges that caused bamboo to languish in comparison to industrialized building products. The new building codes in Peru, Ecuador, and Colombia set the stage for structural bamboo to play a larger role in the urban housing market across the region.

Discussion

r Figure 11. (top) Layers of bahareque (coating bamboo boards with concrete) technique, Santo Domingo, Ecuador, November 2017. (middle) Exposed cane during construction of structural bamboo home. Jama, Ecuador, November 2017. (bottom) Completed home, coated with cement and painted. Jama, Ecuador, November 2017.

Addressing Incremental Construction The rebuilding efforts following the 2016 Ecuadorian earthquake were an opportunity for architects to demonstrate the advantages of building with lighter materials and to showcase the structural capacity achieved when quality material is correctly processed and protected. While the reconstruction projects did an excellent job of addressing housing shortages, the construction technique is still not well-known and is limited to two floors, which prompts a second research question: what catalysts can accelerate cultural acceptance and increase structural use of bamboo in the informal building sector?

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s Figure 13. (left) Transitional housing by CAsitas EMergentes de BAmbú (CAEMBA). Bahia beach construction, single-family home.

Self-help (construction by homeowners/nonprofessionals) and incremental growth are two common strategies that have led to the proliferation of masonry buildings. How can bamboo, a lighter and cheaper material, provide a solution that meets these requirements? An answer can be found in industrialization and the prefabrication of hybridized building products that allow lay people to construct in structural phases.

Future Development: Building for Growth The patented connections developed at USMP (or the like) could lead to an increased use of structural culms and the future development of connecting systems. Products capable of withstanding seismic forces could be rapidly developed and sent to market.

Future applied research is needed to develop a system that anchors threaded rods extending from the USMP device. Ideal designs would allow for disassembly so that as incremental building occurs, the industrialized bamboo product could be relocated above masonry construction. A mobile panel system would allow families to retain a light structure instead of abandoning bamboo outright in exchange for masonry. This hybrid housing solution would meet a family’s preference for industrialized structural materials at the ground level for increased security and status while also allowing them to expand the usable area of their home—without rendering the home vulnerable to collapse. Bamboo enables lightweight, seismic-resistant construction on upper levels and could save lives and buildings during the next large earthquake.

Interview findings, observations during site visits, and analyzing industry challenges reveal two major roadblocks to structural bamboo adoption and use in the informal building sector.

One is the inherent difficulty of self-building, and the other is building expansion through incremental construction. A preengineered bamboo wall panel system would allow people with

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r Figure 12. Bamboo culm end connector with expansion system. As forces pull on the culm, teeth dig into the inside wall of the bamboo.

Developed at the University of San Martin de Porres, Peru. (Credit: Faouzi Jbrane)

Industrialized Structural Systems By introducing standardized elements, such as metal and dimensional lumber, structural bamboo systems can be prefabricated more easily. One such system is being utilized in the Philippines at scale by Base, an initiative of the Hilti Foundation focusing on sustainable affordable housing. 37 Colombian architects were consulted to share bamboo construction techniques to improve the Philippine bamboo economy. The resulting panelized bamboo assemblies combined the prefabrication techniques of the timber industry in Europe with the bahareque wall construction system of Latin America, achieving impressive results (Figure 15). 38 Since 2015, Base has built over 650 homes and has an agreement to build 10,000 bamboo homes using this system; this will require approximately 1.2 million poles over the next five years.

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Structural Bamboo Building Codes

Project

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La Chorerra, Pedernales, Ecuador CAEMBA, Manabi Coast, Ecuador

Construction Type Homes Columns/ Walls Floors Beams 165

Bamboo

500

Bamboo

Bahia Beach Construction, Bahia de Caraquez, Ecuador

20

Bamboo

REFERENCE: Concrete block home

N/A

Reinforced Concrete

Utilities Build time

Plywood

Y

Bamboo Dirt Boards, Wood Frames Metal Mesh Concrete + Concrete

N

Bamboo/ Plaster

Concrete Masonry Units

Concrete

limited construction skills to assemble and expand their home in a safe and flexible format. Developing structural bamboo solutions that respond to the desires and typical development methods of low-income families could have profound impacts on the resilience of the rapidly growing urban centers across the global south. While future research is needed, these proposals outline the potential for sector growth and identify weaknesses in methods of assembly.

Limits Field investigation provided invaluable insights into the challenges and innovations confronting the South American bamboo building industry in this region. The site visits and interviews in Peru and Ecuador, the latest countries to legislate building codes for bamboo, provided access to the frontlines of structural bamboo practice.

There is a need for additional field research in Colombia, which was the first South American country to recognize and legislate bamboo construction in this same region.

This paper presents interview data and evidence from those who are natural proponents for bamboo, as the participants are deeply engaged in material practice, not outspoken skeptics, but rather advocates for bamboo.

One possible direction for extending this investigation would be to follow a specific building project in order to interview residents and conduct a post-occupancy evaluation of new bamboo developments a few years after completion. Additionally, a replicated study conducted in the Philippines could uncover initiatives and innovations appropriate for adoption by the South American bamboo industry.

Conclusion This research demonstrates that structural bamboo housing has the potential to accommodate South American urban population growth in a safe and sustainable way.

Cost

SF/Unit Cost/SF # of Funding 20’ Type Culms 15 Days/ $10,000 1120 $8.93 233 Public duplex Ministry of Housing 1.5 Days $1,500 360 $4.17 30 Private Donations

Y

30 Days

$6,500

540

$12.04

70

Private Donations & Volunteer Programs

Y

Unknown $5,000

380

$13.16

N/A

N/A

The public sector supports regional bamboo treatment centers by consistently purchasing structurally mature culms from farming cooperatives, which helps address material supply chain challenges. Publicly funded housing campaigns and other training workshops disseminate best practices and create demand for both qualified builders and quality building material.

Private sector entrepreneurs and academic institutions are developing new tools that improve the efficiency of bamboo building systems, and the development of international standards assists the scaled adoption of these engineered products.

Future products that could accelerate the cultural acceptance and increase use of structural bamboo in the informal building sector include hybridized building systems that integrate bamboo with metal, and/or wood to improve the longevity and ease of bamboo construction. By extrapolating trends, structural bamboo building systems are increasingly addressing the needs of low-income communities world-wide.

Acknowledgements Portions of this research were conducted for a Master of Architecture thesis at the College of Built Environments at the University of Washington in the fall quarter of 2017. The guidance of Elizabeth Golden and Brian McLaren was instrumental in the development of this work. Financial support for travel was provided by the John Morse Research Travel Fellowship. Pablo Jacome, Yann Barnett, and Raphael Paucas played an instrumental role in connecting the author with architects, contractors, and universities across Peru and Ecuador.

Notes 1.

“Urban population (% of total),” The World Bank (website), accessed February 15, 2018, https:// data.worldbank.org/indicator/SP.URB.TOTL.

WITTE

63

2.

“Population, total,” The World Bank (website), accessed February 15, 2018, https://data.worldbank.org/indicator/ SP.POP.TOTL?locations=XO-XD.

3.

B. Mehta and A. Dastur, eds. Approaches to Urban Slums: A Multimedia Sourcebook on Adaptive and Proactive Approaches (Washington: The World Bank, 2008), 5, http://mirror.unhabitat.org/pmss/getElectronicVersion. aspx?alt=1&nr=1156.

4.

Department for International Development, UN Office for the Coordination of Humanitarian Affairs, Shelter Centre. Shelter after Disaster: Strategies for Transitional Settlement and Reconstruction (Geneva: UN OCHA, 2010), xx-xxi; United Nations International Strategy for Disaster Reduction (UNISDR), Natural Disasters and Sustainable Development: Understanding the Links between Development, Environment and Natural Disasters (Geneva: UNISDR, 2002), 3.

5.

“2010 Haiti Earthquake: Facts, FAQs, and How to Help,” World Vision, accessed November 10, 2018, https://www.worldvision.org/ disaster-relief-news-stories/2010-haiti-earthquake-facts.

6.

W. Salzer and K. Felipe Lopez, “Sustainability of Social Housing in Asia: A Holistic Multi-Perspective Development Process for Bamboo-Based Construction in the Philippines,” Sustainability 8, no. 151 (2016): 127.

7.

N. Van Drunen, ed., Post-earthquake Report on Bamboo Structures and Recommendations for Reconstruction with Bamboo on the Ecuadorian Coast (Quito: International Bamboo and Rattan Organization [INBAR], 2015), 9, https:// resource.inbar.int/upload/file/1500255628.pdf.

8.

“Shelter Projects 2015–2016,” Global Shelter Cluster, accessed January 15, 2018, http://www.shelterprojects.org/ shelterprojects2015-2016.html; A. Gatoo, B. Sharma, M. Bock, H. Mulligan, and M. Ramage, “Sustainable Structures: Bamboo Standards and Building Codes,” Engineering Sustainability 167, no. ES5 (October 2014): 190, https://www.researchgate.net/

s Figure 15. Prefabricated wall panels, Base Bahay Housing Development.

Silay, Negros Occidental, Philippines. June 2018. (Credit: Amy Villanueva)

PEER REVIEW / URBANIZING

IN.ZS?end=2017&locations=1W-XM-XD-XP&start=1960&t ype=shaded&view=chart&year=2017.

r Figure 14. Comparable growth area needed to build bamboo homes vs. timber homes. (Credit: Nick Hall, illustrated by author)

64

Structural Bamboo Building Codes

publication/284345386_Sustainable_structures_Bamboo_ standard_and_building_codes.

9.

Ibid., 192.

10. “ISO 19624:2018. Bamboo structures—Grading of bamboo culms—Basic principles and procedures,” International Organization for Standardization (website), published September 2018, https://www.iso.org/standard/65528.html.

11. “Remains of a bamboo dwelling were discovered in Ecuador that dates to 7,500 BC and an archaeological site in Peru features bamboo reinforcing members in walls dating back to 850 AD.” O. Hidalgo-López, Bamboo: The Gift of the Gods (self-pub., 2003), 365.

12. Van Drunen, Post-earthquake Report, 11.

13. E. M. Golden, Building from Tradition: Local Materials and Methods in Contemporary Architecture (New York: Routledge, 2018), 48.

TAD 3 : 1

14. E. Kessler, “The Resilience of Self-Built Housing to Natural Hazards,” in Affordable Housing in the Urban Global South, eds. J. Bredenoord, P. van Lindert, and P. Smets (New York: Routledge, 2014), 110; P. Smets, J. Bredenoord, and P. van Lindert, “Introduction: Governance, Sustainability and Affordability of Low-Income Housing,” in Affordable Housing in the Urban Global South, eds. J. Bredenoord, P. van Lindert, and P. Smets (New York: Routledge, 2014), 1.

15. “The total number of bamboo houses in Ecuador in 2001 was 254,152 while in 2010 there were 329,416, which represents an increase of 75,264 houses.”

Van Drunen, Post-earthquake Report, 11.

16. E. Kessler, “Resilience of Self-Built Housing,” 75.

17. P. Ward, “Latin America’s Innerburbs: Towards a New Generation of Housing Policies for Low-Income Consolidated Self-Help Settlements,” in Housing Policy in Latin American Cities: A New Generation of Strategies and Approaches for 2016 UN-Habitat III, eds. P. Ward, E. Jiménez Huerta, and M. Di Virgilio (New York, Routledge, 2015), 4.

18. Van Drunen, Post-earthquake Report, 25.

19. E. Kessler, “Resilience of Self-Built Housing,” 82.

20. M. de los Angeles Duarte, Estructuras de Guadúa: CODIGO NEC-SE-GUADÚA (Quito: Ministerio de Desarrollo Urbano y Vivienda, 2016): 19.

21. Golden, Building from Tradition, 1.

22. Van Drunen, Post-earthquake Report, 25.

23. “INBAR Publications,” International Bamboo and Rattan Organisation, accessed November 27, 2018, https://resource.inbar.int/download/download. php?lang=cn&class2=103.

24. “Premio Sacha,” Premio Sacha (website), accessed November 27, 2018, http://premiosacha.org/.

25. Unfortunately, scheduling, funding, and safety concerns did not permit for research in Colombia, which has the most developed bamboo building industry in Latin America and the oldest bamboo building code in the South American continent.

26. N. M. Riaño, X. Londoño, Y. López, and J. H. Gómez, “Plant growth and biomass distribution on Guadúa angustifolia Kunth in relation to ageing in the Valle del Cauca—Colombia,” Bamboo Science and Culture: The Journal of the American Bamboo Society 16, no. 1 (2002): 43, http://www.maderinsa. com/guadua/fijacion.pdf.

27. Ibid., 43.

28. Salzer, “Sustainability of Social Housing,” 151.

29. Annual competitions for eco-friendly materials are promoted by the Peruvian Ministry of Housing: http:// www.construyeparacrecer.com/.

30. J. Morán Ubidia, Construir con bambú caña de guayaquil, 3rd ed., eds. Yann Barnett, Faouzi Jabrane, and Alejandro Expinoza (Quito: International Bamboo and Rattan Organization [INBAR], 2015), http://www3.vivienda. gob.pe/dnc/archivos/Estudios_Normalizacion/ManualConstruccion-Bambu.pdf.

31. Ibid.

32. Universities visited include the Universidad de San Martin de Porres, Lima, Peru; Universidad Católica de Santo Domingo; Universidad Católica de Guayaquil; and the Universidad Laica Eloy Alfaro de Manabí.

33. “Instituto de Vivienda, Urbanismo, y Construcción— actividades,” USMP (website), accessed November 17, 2018, http://www.usmp.edu.pe/ivuc/actividades.php.

34. “Red Sibguadua, eventos anteriores,” Red Sibguadua (website), accessed November 17, 2018, http:// redsibguadua.org/eventos/index.html.

35. Barnett, Y., and F. Jbrane. Conector de extremidad de tallo de bambú con sistema de expansión. INDECOPI Peru Patent 1321-2017, filed August 4, 2017. Patent pending. http://www.usmp.edu.pe/ivuc/pdf/proyecto conector bambu.pdf 36. N. Hall, “The Costa Rica National Bamboo Project,” Basin and the City Summit News no. 11, March 11, 1996, http://www. nzdl.org/gsdlmod?e=d-00000-00---off-0hdl--00-0----010-0---0---0direct-10---4-------0-1l--11-en-50---20-about--00-0-1-00-0--4----0-0-11-10-0utfZz-8-00&cl=CL2.23.1 &d=HASH013b8b8f564d8610532a7feb.7&gt=1.

37. “A Secure Future—Constructing with Bamboo: Manila, Philippines,” Hilti Foundation, accessed November 27, 2018, http://www.hiltifoundation.org/en/ Base-builds-constructing-with-bamboo.

38. Salzer, “Sustainability of Social Housing,” 151.

David Witte is an advocate for holistic solutions to homelessness in Seattle, Washington. He is a member of the AIA Seattle Committee on Homelessness (COHO) and a former Co-Chair of Unite and Ignite, a subcommittee focused on community service within the AIA Seattle Young Architect’s Forum. Witte previously lived and worked in Peru as a Peace Corps volunteer and a project designer for Architects Without Borders.