Safe and Affordable Urban Housing in Bangladesh

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Safe and Affordable Urban Housing in Bangladesh Promoting better building techniques in Dinajpur Town – a Case Study

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Safe and Affordable Housing in Bangladesh

Disseminating better building techniques

Team:

John Arnold

Azit Roy

Marianne Keating

Sam Stephens

Shareq Rauf Chowdhury

Poramol Roy

Pulin Roy

With thanks to:

Apu Chandra Roy

Imran Morshed Khazi

Ishita Alam Abonee Ishita Mouri Rahman

Khaled A Sheikh

Mahmuda Alam

Orko Jahanjir

Rubiyat-ur-Rahman

Showeb Al-Kadri

Tushar Kanti Roy

Uzzal Roy

With support from:

Simple Action For the Environment (SAFE) safebangladesh.wordpress.com

Housing and Hazards www.housingandhazards.org

Australian High Commission

British Women’s Association (Dhaka)

Urban Partnerships for Poverty Reduction (UPPR)

http://safebangladesh.wordpress.com/

http://www.housingandhazards.org/

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Contents

Contents .......................................................................................................................................................... 3

Executive Summary ......................................................................................................................................... 4

Introduction .................................................................................................................................................... 5

The place and people ...................................................................................................................................... 8

Participatory Design and Construction – the process ................................................................................... 13

12. Recommended construction improvements .................................................................................... 16

Adaptable house designs for Jorgen Babur Mart ......................................................................................... 23

Costs .............................................................................................................................................................. 26

Key Issues, Chellenges and Next Steps ......................................................................................................... 27

List of Appendices ......................................................................................................................................... 30

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Executive Summary

This report details a pilot project to design and build 10 safe and affordable homes in a slum area in Dinajpur

town, in the north east of Bangladesh. A multidisciplinary team of architects, engineers and a local NGO (SAFE)

worked with a slum community to identify and demonstrate improved construction techniques using traditional

materials. The principle behind these improvements is that they remain affordable but produce a house which is

more liveable, safer and ultimately lasts longer – saving households money in the longer term and leaving them

less vulnerable to disaster.

The aim of this project was to demonstrate these improvements in such a way that they would be replicated by

the local community after the project was finished. To this end a participatory process involving local families

was used during the design and construction so that improvements would be appropriate and understood by all.

Although it is too early to see if techniques have been fully accepted and replicated, the participatory process was

successful and a strong relationship formed between the NGO and the community. This helped the construction

work go smoothly with few delays. The 10 demonstration houses and input from the NGO were almost fully

subsidized, but with labour and in some cases financial contributions from the households. Even at this early

stage, it is clear that households are taking pride in their new homes, carrying out regular maintenance and

contributing to a local savings scheme dedicated for future maintenance.

Different contexts (i.e land values, environmental conditions, resources available) will require different housing

solutions, and any significant investment in housing will require some degree of secure land tenure. This project

focuses on low-cost low-rise, typically self-built housing that would be appropriate for households with limited

resources, or/and a limited security of tenure (eg.10 year lease or ‘right to stay’).

Supporting households in self-built housing offers an opportunity to rapidly increase the supply of safe low-

income housing in Bangladesh. This project demonstrates an approach that supports this mode of construction to

produce safer and more economical houses in the longer term. Key to the project is not just the technical

elements but its participatory nature, designed to transfer skills and understanding to the local community so

that the ideas might be replicated in the future.

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Introduction

Urbanisation - an opportunity

Urban populations in Bangladesh have seen huge growth since the country’s independence in 1971.

Approximately 40 million (25% of the population) people now live in towns or cities compared with

8% at independence1. Dhaka, the capital, has approximately 16 million inhabitants and is the 9th

largest and one of the fastest growing cities in the world.

Much of this urban migration can be attributed to economic opportunities. Urban populations now

contribute to over 70% of the national GDP. Managed well, towns and cities can be drivers of

economic growth, and can be seen as Bangladesh’s best opportunity of reducing poverty2.

Unfortunately Bangladesh’s towns and cities are ill equipped to manage this growth, which places

huge demands on space and infrastructure. Scarcity of land, poor transport, lack of planning and lack

of affordable credit often makes it difficult for people, especially lower income groups, to find

suitable housing convenient to their place of work. The result has been a huge increase in the

numbers of slums – areas of housing characterised by lack of secure land tenure, lack of formal

services like water or electricity and cramped, insanitary conditions.

Project scope

Different contexts will require different housing solutions: a site in Dhaka where land values are high

may preclude anything but multi-storey development in order to keep unit costs down; a household

owning land maybe willing to invest in more permanent housing than a household with informal

rights; a household who are not saving, or planning for the future beyond the current year are

unlikely to be ready to invest in their own housing at all, preferring perhaps to rent.

This project focuses on low-cost low-rise, typically self-built housing that would be appropriate for

households with limited resources, or/and a limited security of tenure (eg.10 year lease or ‘right to

stay’).

1 Islam, Nazrul and Salma A. Shafi (2008) “A Proposal for a Housing Development Programme in Dhaka City,” Centre for Urban Studies (CUS), Dhaka. 2 World Bank (2007) ”Bangladesh: Strategy for Sustained Growth”. Bangladesh Development Series, Paper no. 18. Dhaka, Bangladesh.

Aerial view of Jorgen Babur Mart

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Self-built housing – an opportunity

Self built housing is the prevalent mode of construction among low income groups in Bangladesh.

Self-built, in this context, means that the homeowner is closely involved with every aspect of

construction. For a household with limited resources it offers the most economical approach:

improvements can be carried out incrementally as resources become available or as need requires

(eg. adding an extra room for a newly married son). Self-construction is not usually guided by any

safety standards, but by word of mouth and informal knowledge, and can often lead to hap-hazard

buildings which are vulnerable to hazards such as earthquakes or storms. However self-construction,

if properly supported, presents an opportunity to increase the supply of affordable homes which are

safer and longer-lasting.

The issues of securing tenure and access to finance –of which both have a huge affect on the type of

housing options available are beyond the scope of this project.

Communicating improved self-built construction

There are many issues and constraints which will influence a project aimed at improving self-built

construction practices. Important factors that should be considered include:

Òpportunity cost of households time. Time is money, especially in slums. Households may not be

able to afford time to participate and so those households who spent significant time attending

workshops during the planning stages were compensated. Other workshops and events were

held on Fridays when residents were not working.

Security of tenure. If there is a threat of eviction then households are unlikely to want to invest

money in their home. The families involved in this project held ‘right to stay’ documentation

from the local government, and had been settled for many years without threat of eviction.

No extra cash. Resources are scarce, and when they are available households have to balance

many competing demands for their use. To invest in housing, households must be thinking and

planning several years ahead and saving accordingly.

Benefits of improved housing may seem marginal. In the face of many (more immediate) risks,

the threat of a risk such as a storm, and its potential impact on health, livelihood etc may seem

too far off to justify importance.

Further to these, any improvements in construction are more likely to be replicated if they are: A workshop with local community to explain the techniques being used in the

construction of the new houses.

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Desirable. One of the main challenges to this project is that traditional materials, such as

bamboo and mud are often associated with poverty/low status.

Simple and affordable

Available locally. includes not just materials but also skilled labour within local communities.

Their benefits are fully understood. For example, if a household is going to pay extra money for

treated bamboo they must be aware of the payback period.

To address these issues fully – to understand what people have and what they want, to share ideas

and to have them understood - a participatory approach which builds trust between all parties

provides many advantages. The participatory process we have followed in this project is outlined in

later chapter ‘Participatory Design and Construction – the process’. An important component of the

process is that learning is transferred to the local community and builders through doing practical

work – building demonstration houses or through practical workshops, considered much more

effective and appropriate means of teaching in this context.3

3 ‘Learning by doing’ –Ian Davis, (1996), Shelter After Disaster

An initial meeting between SAFE and community members

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The place and people

Jorgen Babu Mart is an area situated approximately 2km from the centre of Dinajpur town. Originally

the land belonged to Jorgen Babu, a Hindu land owner who emigrated to India during the partition of

India and the former East Pakistan. The government is now the de-facto owner of the land.

Households do not possess individual title deeds but many do have ‘right to stay’ documents from

the local government. The area has been established for many years and with threat of eviction low

many households have invested in pucca (permanent) housing.

This project has focussed on one section of Jorgen Babur Mart inhabited by approximately 50

families. The land they occupy was once waterlogged and uninhabitable but was reclaimed

approximately 7 years ago by the NGO CARE. Many of the families were previously squatting on land

belonging to Bangladesh Railways.

The people who make up this area of Jorgen Babur Mart are both Hindu and Muslim. They have come

from different parts of the NW of Banlgadesh and many for economic reasons. They are involved in

occupations ranging from TV-repair men to day labourers to rickshaw pullers and earn between

Tk.100-250 per day. Although some women work outside the area, most stay at home but generate

extra income through home-based activities such as poppadom rolling or handicraft production. In a

survey of 30 of these families over half had existing micro-loans and a similar number also held small

savings with 1 of 3 organisations. Detailed interviews of 10 households are given in appendix G.

DINAJPUR

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Nurul Islam

Nurul lives in a small single room house with his wife Hasina and his two youngest children Hasan and Sumi. They moved

to Jorgen Babur Mart in 2001 with help from NGO CARE after being evicted from there previous house in a nearby slum.

He did not start life out in Dinajpur, but was born in Dhan Ghora, a

village near Rangpur about 60km to the west. He lost both parents

within the first year of his life – his father died before he was 2

months old and his mother suffered from mental illness and

disappeared. He was taken in by his grandmother who looked

after him throughout his childhood. In 1974 when Nurul was

about 11, Bangladesh suffered severe famines under the new

government formed after independence with Pakistan. Nurul

came to Dinajpur with his grandmother in search of work and

food. They settled in a slum area called Sheshshahir Moor Bosti

where he remained until the slum was cleared in 2001.

During that time Nurul marries Hasina, they have 3 children and

he has a variety of jobs including cart puller and lorry driver’s

assistant. It is during this last job that Nurul suffers a severe

accident which affects his back and leaves him unable to walk for

3 years – relying on help from his family to move him around.

With no savings, he is unable to get any professional medical help

and Hasina starts working full time as a day labourer to

compensate. With the help of pain killers and a bamboo brace, he

slowly regains strength and starts to walk and work again.

With his back partially recovered things are better. He now works

as a rickshaw peddler earning Tk150-200 per day, though can

only manage about 3 days a week due to back pain. His wife

works as a house builder, often 7 days a week when there is work.

They save Tk10 a week as part of an NGO savings scheme but

currently only have Tk400. Their daughter, Sumi, age 9, attends a

nearby BRAC school in the afternoons. When she grows up she

wants to be a teacher. Hasan, 7, doesn’t like going to school and

often truants despite being taken there by his mother before she starts work. He is falling way behind and his mother is

worried that he will drop out completely. She tells us with an exasperated look how he recently sold his books in exchange

for some peanuts.

Their house is not the best – small at 9ft x 18ft, in poor condition and located next to the communal toilets. Despite that he

is proud and happy to have his own land without the threat of eviction. Owing to the poor condition of his home, Nurul’s

home was chosen by the community to be the first demonstration house to be built.

Nurul and family outside their home in Jorgen Babur Mart

Shahin Islam in his bedroom and study he shares with his brother. There are

no windows.

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Physical environment

Housing in this area is linear with plots laid out on two sides of a single narrow lane. On either side of

the lane behind the plots run two surface drains. Communal toilets have been built in the centre of

the area. This infrastructure was provided by INGO CARE when the land was reclaimed, but is in

poor condition with no structures set up to take responsibility for maintenance.

Plot sizes vary between 8ft x 18ft up to 30ft x 18ft and are often divided up into several small rooms

to cater for 3 generations of the same family. The houses area simply constructed with a bamboo

frame, lean-to roofs of Corrugated Iron (CI) sheet and wall materials of either CI sheet or bamboo

mat. Several houses have private tube wells and 2 houses have private latrines constructed in

partnership with the Urban Partnerships for Poverty Reduction project. A formal electric connection

exists to the area with many households connected. A few trees exist within the plots though there is

little greenery and no households grow any vegetables.

Plan of existing house for 8 family members

Plan of existing house for 8 family members Plan of existing house for 8 family members

A typical cross-section of existing housing – see plan overleaf

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Existing Problems and Opportunities

All houses lack adequate ventilation with very few windows or gaps to allow natural ventilation.

As a consequence many households use electric lights and fans during the daytime.

The CI sheet used for roofs and walls provides very poor insulation and rooms are stiflingly hot

during the day and cold during the winter.

The drainage of the whole area is poor and all houses are regularly flooded during the monsoon

season. This is compounded by the poor maintenance of the existing surface drains.

Most households cook on small portable clay stoves, and burn locally purchased wood. Without

adequate ventilation many women prefer to cook outside, however when it is raining the

resulting smoke inside the houses is a problem.

With up to 3 generations sharing a small plot, space is a real issue. A husband, wife and

children will often sharing a room as small as 11’ x 9’. As a consequence and owing to the heat

many women who roll and dry poppadoms prefer to do so in the congested and dirty lane

outside.

Existing settlement pattern. Households involved in construction are highlighted.

Drains running behind houses are not regularly maintained and flood

intermittently during the rainy season.

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The bamboo used in construction rots quickly in the ground and is subject to attack from insects

above. Posts need to be replaced every 1-2 years but are often left leaving houses weak.

With many families living in the area for a long time there is a strong sense of community

Drains and toilets exist, but just needs to be properly maintained.

Strong winds do occasionally affect the region however they are of a much smaller scale that

the cyclones affecting the south of Bangladesh. The area is not exposed.

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Participatory Design and Construction – the process

The design process has been undertaken in conjunction with the community and local builders. This

is important to ensure that our design matches the requirements of the households, and is specific to

Jorgen Babur Mart – using available materials and addressing the issues specific to this place.

The process is designed to build trust between all parties and to ensure that all households and

builders understand the improved techniques we are promoting.

The process we have undertaken for this project is as follows:

1. Initial meetings. Primarily with the Community Based Organisation and then the whole

community to explain the project.

2. Study. This involved short survey of approx. 30 households within community including

identifying existing house types and construction techniques; identification of local builders,

available materials, and; mapping of the community.

3. Selection of 10 households. Households were chosen by the community based on need, and

verified by our own surveys. The chosen households were announced by the CBO at a

community meeting.

4. Dream house workshop. A 1 day workshop attended by the 10 households, CBO members and

facilitated by the SAFE team and architecture students from BRAC University. Each

household was given materials and asked to build their dream house – the only constraints

being that it must be on their existing land. This helped us to understand what people wanted

in terms of their space requirements. Ideas which came out of this workshop included an

area for growing vegetables, extra flexible space - for guests, for children to play and for

income generating activities like drying poppadoms. To get this extra space many households

built 2 storey houses. At the end of this workshop the group decided on who would build the

first house.

5. Initial design. Appropriate improvements were selected by the design team and design

options worked up. A tentative budget of US$500 for construction was developed.

6. Design workshop. A 3 day workshop attended by local house builders, households, CBO

members and facilitated again by the SAFE team and architecture students from BRAC

University. Participants present their dream houses

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The first part of the workshop was used to show people improved building techniques as

practiced by SAFE. This included a practical demonstration of a low cost method of treating

bamboo. A local song team attended and sang songs which reinforced these messages.

The second part focussed on developing initial designs. Working in mixed groups – builders,

household members and architecture students, models were built of two different designs

which incorporated the improvements discussed on the first day of the workshop. Next the

groups worked out the costs of each house. These came out higher than the tentative budget

set previously and the groups were encouraged to find ways of reducing costs, whilst

maintaining the agreed improvements. These included recycling materials from their old

houses, reducing optional extras like expensive window and door frames, households adding

their own money and/or undertaking more of the labour themselves. At the end of the

workshop a timeframe for construction of the first house was agreed. See Appendix H for a

detailed programme from this workshop. The workshop programme is detailed in Appendix

H.

7. Detailed design and costing. Two generic designs were developed and costed by SAFE and

BRAC architecture students. The full costing which has been developed further during

construction phase, is given in Appendix C.

8. Construction of first demonstration house. Although the costs for the basic house were met be

met by the project, responsibilities were agreed between SAFE and participants: households

were be responsible for dismantling houses, keeping site clean, providing 2 people daily for

labour during construction and carrying materials to site – this was recorded clearly in an

informal written contract between SAFE and the household. The first house provided an

opportunity to review the design and construction as people at full-scale.

9. Regular workshops. As the construction progressed a further 6 practical workshops were

carried out. These workshops further reinforced understanding about the house design and

construction techniques. To try and spread the word, different participants were invited –

other households from the same area, and builders and other community leaders from

surrounding slums.

10. Construction of remaining 9 houses. Following a review of the first house, and with

improvements taken on board for the remaining houses, a timeframe for the construction of the

remaining houses was agreed and construction commenced. Houses were built incrementally

BRAC architecture students, builders and household work on

the design during the workshops

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with up to 3 (connected row) houses at a time. Construction of 1 house with approx 4no.

builders took on average 3-4 weeks. As the construction continued, leaders emerged from the

building team and more responsibility was placed on the builders and households with SAFE

taking a more ‘hands off’ role.Local play or ‘jattra’. An evenings’ programme of events was

organised to further promote the project within the immediate community. This including

performances from a local song team, and a short play acted by the local builders and

participating households. The play and many of the songs reinforce the safer building

techniques of the project.

11. Promotional leaflets. Instructional leaflets were produced in Bangla giving further information

on cross-bracing techniques and distributed amongst residents of Jorgen Babur Mart. See

appendix C.

12. Savings group for maintenance. Although these houses may require less maintenance that traditional

techniques, regular maintenance is still essential if the houses are to remain strong and safe in the

longer term. The 10 households were encouraged to start a savings group. A small weekly amount is

deposited with the savings groups leader and this money could be used when repairs were needed.

Local community members learn about cross-bracing and cement stabilisation of earth during practical workshops

Local builders promote the project in a jattra (local play)

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Recommended construction improvements

Rather than produce a single design to be indiscriminately copied SAFE recommends a range of

design improvement options. These are modest technological changes that will increase the

performance of existing housing types by strengthening or improving parts which are particularly

weak or vulnerable to the local climate. This will save households money in the long run through

increased longevity of materials while making them less vulnerable to hazards such as floods or

strong winds.

These improved building techniques use available materials and are low cost – scaled to the actual

costs that low income households invest in housing. We aim for these improvements to increase total

costs of building by only 20%. Techniques are based on practical experience from SAFE’s team and

existing best practice on the subject4,5,6. Techniques are context specific but would be applicable in

many locations throughout Bangladesh.

This approach is adaptable. It acknowledges that no two houses are the same – different people have

different aspirations, family sizes, occupations and budgets, and as such will need different houses.

1. Plinth Stabilisation and preparation.

Flood water and rain causes cracking and damage to mud plinths. They require regular

maintenance and obtaining this mud from local sources can be problematic. When flood water

enters the house floors become muddy and create a poor environment.

Stabilising the plinth with a small amount of cement has been found to substantially increase its

resistance to dampness and erosion by water, preventing the need for regular maintenance. The

entire plinth does not need to be stabilised - only a capping layer of approximately 3 – 6in. Prior

to this the plinth should be constructed in compacted layers of regular soil. The plinth should

have a minimum slope of 1% for drainage.

Cement stabilisation is suitable for soil that has a low clay content. Soil with more than 10% clay

content may need to be modified by the addition of sand.

4 Iftekar, K.A. (2005) Handbook on Design and Construction of Housing for Flood-Prone Rural Areas of Bangladesh, ADPC. Available at www.sheltercentre.org 5 Mallick, F.H. et al.(2008) Improved design and construction of rural housing in Noakhali, IUCN. 6 Chisholm, M.P. (1979) A study of the provision of rural housing in Bangladesh. BArch thesis, vols. I & II. University of Newcastle upon Tyne, UK.

Plinth capping with cement stabilised mud – taken from Handbook on Design

and Construction of Housing for Flood-Prone Rural Areas

http://www.sheltercentre.org/

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2. ‘Kaatla’ or concrete stump

When in contact with the ground bamboo posts rot quickly in as little as 1 year. The use of a

concrete stump ensures that the bamboo is raised above the ground level. A good connection

between the kaatla and the bamboo is required. For the two storey buildings constructed in this

project we recommend a slightly larger kaatla than shown adjacent in order to resist uplift from

the wind – see drwg MCL100-005 in Appendix B.

3. Bamboo treatment

Untreated bamboo will be attacked by insects and a life-span of approximately 4-6 years can be

expected. Treated bamboo should last 15–20 years if it is kept protected from the elements.

A cost effective way of treating bamboo, undertaken previously by SAFE, uses a solution of

borax, boric acid and water. This solution penetrates the bamboo easily, reducing the level of

sap in the bamboo and making it less likely to be damaged by insects. The method used here is

known as the Vertical Soak Diffusion technique7: the bamboo is stacked vertically and the

solution is poured inside from the top end (prior to this a hole was made in each diaphragm

using a long metal rod, hammered into one end; the last diaphragm being left so that water

7 Vertical Soak Diffusion for Bamboo Preservation, Environmental Bamboo Foundation, 2003. www.bamboocentral.org

Bamboo treatment with borax/boric acid solution

Above: Kaatla or concrete posts; left: bamboo treatment using vertical soak

method

http://www.bamboocentral.org/

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would be contained within the bamboo). This method increases the cost of the bamboo by

approx. 20%.

4. Cross bracing

Cross bracing and plan bracing are essential to increase stability in high winds. Currently very

few houses use cross bracing. The location of the cross bracing and the connection between to

the frame is important to ensure that it functions correctly. As part of this project, field testing

was undertaken to determine the strength of these bolted connections, and simple guidelines in

English and Bangla produced to ensure correct installation of cross bracing. These can be found

in Appendices D & E. The position of cross bracing is also detailed in the design drawings in

Appendix B.

Plan bracing

Cross bracing

> 50mm/ 2”

Cross bracing fixing detail. Fixing no less than 50mm from end of culm with a

node between the fixing and the end. Refer to Appendix E.

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5. Stronger joints

Existing practice is to use jute string (natural and degrades quickly) or nails (which can cause

culm to split). It is essential that good connections are made between the foundations, walls and

roof to ensure that the structure is not damaged during strong winds. Bolted connections were

used where stronger connections were required - between wall posts and foundations and first

floor joists and for cross bracing. Bamboo nails and nylon string were used in other locations.

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6. Wall materials

Different wall materials depending on the location:

Wattle and daub type. Mud stabilised with cement is applied to a bamboo lattice approx

1-2” thick. This type of wall requires regular maintenance if exposed to rain and so is

best suited to walls protected by a roof overhang. The mud provides better insulation

than materials such as CI sheets or bamboo mat.

CI sheet/bamboo mat. CI sheet is placed on the lower part of the wall where it is more

likely to get wet and with bamboo matting above. This reduces costs while maintaining

the longevity of the wall.

7. Stronger roof structure

Improvements to the existing construction were used which will make the roof structure more

resistant to strong winds:

Roof form pitched with a slope between 30-40 degrees where possible.

Overhangs should be 2ft 6in to provide protection from rain whilst resisting uplift by

wind.

Strong connections should be made between the roof structure and the walls using nylon

string and bamboo nails as shown in (5).

CI sheets should be fixed at every 3 corrugations with twisted roofing nails and at every

2 corrugations along edges.

CI sheet should be of minimum gauge 0.35mm. Thinner CI sheet is widely used but is less

cost effective due to its shorter life span.

Cement stabilised ‘wattle and daub’ wall

Extra fixings at the bottom of the sheet

CI sheet at the bottom of the wall where subject to

splash back from rain improves longevity

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8. Ventilation, insulation and lighting

Adequately sized, lockable windows were included. Windows were constructed with

timber frames and bamboo slats. Refer to Appendix A for more pictures of the completed

houses.

Bamboo louvers at the top of walls were used to increase the amount of airflow, however

these were omitted in later houses due to cold drafts in the winter months.

A trial ‘solar bottle bulb’ was installed in the roof of one house as well as clear plastic

roof sheet. A report on the installation and costs of these is given in Appendix F.

Flat ceilings of bamboo mat were installed underneath the roof, to provide a degree of

protection from the heat transmitted through the roof sheets.

For the two storey houses the first floor was made using a bamboo joists and slats, with

a 1” layer of cement stabilised mud. This mud layers provides a degree of insulation to

the room below.

Louvers at the top of the wall for improved ventilation

Solar light bottle bulb Windows improve ventilation and lighting

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9. Kitchen garden and planting

The growing of vegetables offers an opportunity for households to save money and eat a more

nutritious diet, while improving their immediate environment. Vegetation and planting were

encouraged through:

Promotion at workshops, where pictures of ‘good practice’ from other slums were shown.

The houses were designed with space at front and back to allow for planting.

Frames were provided to encourage climbing plants.

A competition was held where prizes were given to households who had done the best planting.

10. Improved cook stove

GIZ’s (German govt.s development organisation) improved cook stove or ‘bondo chula’ is

available locally. When maintained and used properly it will reduce fuel consumption by up to

40% from a traditional stove. It would be installed with an exhaust flue to remove smoke from

the kitchen area. Where budget permited, households installed improved cook stoves.

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Adaptable house designs for Jorgen Babur Mart

Although all the houses are slightly different, owing to households’ needs and space constraints, they

were based on 2 generic designs for a single storey and two storey (ground+1) building. Photos of

the houses are given in appendix A. Architectural and structural design drawings for these houses

are found in appendix B.

Structural calculations were undertaken for the two storey house to ensure the house would resist

strong winds. Calculations were made using the Indian Design Code IS85:1987 and a design wind

speed of 139km/h. Using this wind force and the dimensions of the house, forces acting on the cross-

bracing were discerned. Practical testing of the bamboo cross-bracing connections was undertaken

to ascertain their ability to withstand the expected forces and is shown in Appendix D. A 100kPa

allowable soil bearing pressure was used to size foundations to resist forces arising from gravity

loading as well as overturning due to wind. By inspection, wind-force design will be sufficient to

account for expected earthquake forces.

The features of the design which offer significant improvement from existing practice are as follows:

Single storey design (refer to Appendices A & B for further photos and architectural and

structural sketches)

The design features of this house, other than the improvement mentioned above are as follows:

One storey house as per the space requirements

2 ft. recess from the narrow lane has been provided at the front to allow space for growing

vegetables and plants

Space has been allowed for the later provision of a tube well and latrine.

Kitchen at the rear allows easy access to drain and proposed tube well.

Retractable door at the front to allow overnight storage of rickshaw.

Louvers to allow improved ventilation and access for drying popadoms on roof.

Wide door allows overnight storage of rickshaw

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Two storey row house (refer to Appendices A & B for photos and architectural and structural

sketches)

The design features of this house, other than the improvements mentioned above are as follows:

Two storey house so that family has extra space

Veranda on 1st floor overlooking street to provides utility space for activities such as drying

clothes and rolling popodoms, whilst allowing users to socially interact with neighbours.

Shared wall between adjoining properties, which saved costs. A written agreement between

the neighbours to clarify responsibilities for maintenance was drawn up.

2 ft. Set back from the lane has been provided at the front to allow space for growing

vegetables and plants. Space also provided at the rear for the same.

Space has been allowed for the later provision of a latrine towards the rear.

Kitchen at the rear allows easy access to drain and proposed tube well.

Pitched roof provided more strength in high winds.

Balcony

Discussing the design of the first house with the household and builders

25

26

Costs

A detailed cost breakdown for each house type is given in appendix C. The costs for materials and

labour (excluding the costs for design, workshops and other costs for SAFE to manage etc) are as

follows:

Single storey house (Nurul’s)

Total floor area – 256 sqft

Total cost – Tk 41,728 ($ 521)

Total cost per sqft – 160Tk/sqft ($2)

Two-storey house (Rubi)

Total floor area – 284 sqft

Total cost – Tk 39,597 ($495)

Total cost per sqft – 139Tk/sqft ($1.74)

The relative difference between the two designs can be explained by the significant cost of the metal

roofing sheets. The 2-storey house has a smaller footprint than the single storey house and therefore

required less roofing sheets.

27

Key Issues, Chellenges and Next Steps

Take up by other households

At the time of writing only 5 months had passed since the final house was completed. This is too

early to assess whether improved techniques are being copied in the wider community and a further

assessment will be required at the end of the following construction season (June 2013).

One barrier to this will be the social stigma attached with traditional materials such as bamboo and

mud - associated with poverty and low social status. The aspiration of most households is to own a

brick or ‘pukka’ house. It is hoped that because the houses look distinctive, that they combine new

ideas with traditional materials, and ultimately because they are significantly cheaper than brick

houses that this may be overcome.

Another barrier is that the total cost of the houses still far exceeds what many people could afford

through their own savings. Many of the improvements used in this project can be implemented

incrementally, reducing the need to make a large one off investment. However it is important to note

that savings programmes and access to affordable credit for housing construction are key to enable

poor households to improve their housing. Linking the provision of credit with improved self-build

construction has been trialled with some degree of success in Delhi by Micro Home Solutions8

Participatory design and construction

At this stage it may be too early to tell whether the participatory process has successfully passed on

information to the wider community. However the participatory approach helped to make the

construction phase run smoothly. Working in such a small area with poor access and shared with

many other families it was important to have the full cooperation and trust of the community to

ensure there were no delays. Also even at this early stage, households are taking pride in their new

homes, carrying out regular maintenance and contributing to a local savings scheme dedicated for

future maintenance.

During the construction it was planned that more control would be handed over to local builders and

households, especially with regard to finance. Although households were involved to some degree in

the purchasing of materials, most of the financial planning and accounting was done by the SAFE. In

8 Micro Home Solutions (2011), Self Construction: enabling safe and affordable housing, available at www.microhomesolutions.org

http://www.microhomesolutions.org/

28

reality for this to happen the money needs to be in the hands of the household – either in the form of

their own funds, or perhaps given by the NGO at staggered intervals during construction (eg. After

successful completion of the foundations, money is given for the walls).

Scaling up

In this project the costs the houses were fully subsidized. It is likely that subsidies will always be

required to demonstrate and promote new techniques such as these, but it is hoped that households

could meet more of the costs as SAFE has done in its rural programmes. Again, the presence of

savings and affordable credit amongst the community would be important here.

Below is an outline framework for the participatory approach used here (detailed more in the

previous chapter ‘Participatory Design and Construction – the process’). With the training of

community level building specialists at its core, it is a model which could be replicated at scale across

many communities in Bangladesh, given some security of tenure and access to savings or affordable

credit.

Steps Objectives Activities

1. Initial study Familiarisation with locality and it’s problems;

Develop potential design improvement options;

Build relationship with community;

Survey

Documentation of settlement patterns, existing house typologies, costs of construction and impact of disaster on households.

Focus group discussions;

2. Design To decide on design improvement options appropriate to place;

To agree improvement options with local builders and households;

Design workshop involving participating households, local builders;

Focus group discussions;

Build models with the community

3. Design and Implementation

To demonstrate design improvements;

To train local builders and households in these new techniques;

Construction of one demonstration house using design improvement options.

Mini-workshops to train builders and households about improved construction techniques.

Ensure participation by the household including decision making and contribution of labour and available resources;

Review and make changes to design improvements where required.

4. Transition/Exit To make local people independent from external consultants; Construction and/or strengthening of 5-10 houses, replicating activities from step (3);

29

strategy SAFE team to take a more ‘hands-off’ role with responsibility for construction quality, costs and programme transferred to builders and households.

Undertake more workshops to disseminate within wider community and other poor communities in local area.

Promotional activities: produce leaflets & other media such as local play; provide limited no. of small subsidies for using new techniques – giving more exposure within the community.

Link other poor communities in the town. Involve them in workshops, try and create links between community leaders.

List of Appendices

Appendix A - p31

A selection of photos of the houses during and after construction

Appendix B - p36

Key plan of location of houses and house owners

Sketch of cross section of Rubi & Shabitribala’s house looking east.

Sketch of typical single storey house

Structural drawings for typical 2-storey house

Appendix C - p48

Cost budget for single storey house

Breakdown of costs for 2-storey house (Rubi and Fahima’s)

Appendix D - p52

Field tests of bolted bamboo connections

Appendix E - p68

Simple guidelines for cross-bracing - leaflet

Appendix F - p73

Solar light bulb installation report

Appendix G - p79

Location key plan of households & interview of household

Appendix H - p89

3-day design workshop programme

Appendix A

A selection of photos of the houses during and after construction

Appendix B

Key plan of location of houses and house owners

Sketch of cross section of Rubi & Shabitribala’s house looking east.

Sketch of typical single storey house

Structural drawings for typical 2-storey house

Appendix C

Cost budget for single storey house

Breakdown of costs for 2-storey house (Rubi and Fahima’s)

Cost budget breakdown for typical single storey house rev 2 06.07.11

NotesThese figures are budget costs only and based on outline design for single‐storey house shown in Appendix BLabour is assumed at 200Tk/dayHousehold is assumed to provide 2 labourers throughout constructionCost does not include extra cost of SAFE supervision, training or transport costsLabour costs given are minimum ‐ the first 2‐3 houses will require approx. 50% more labour as builders are learning new techniques and designCI sheet = Corrugated Iron SheetAssume recycled Corrugated Iron (CI) sheet 270 sqft Total floor area 256 sq.ftImproved cook stove not included in price

Quantity UnitMaterial Cost (Tk)

Labour Cost (Tk)

Total cost (tk)

1 PlinthPlinth volume = 1' x 266 256 cuftAssume compaction ration of 0.75Total volume of earth required 341 cuftVolume of 1 trolley 90 cuftTotal no. trolleys required, say 4Cost of 1 trolley of earth 500 TkTotal cost of earth for plinth 2000Labour for carrying and placing earth 400

Sub‐total 2400

2 Stabilisation of capping layerAssume average thickness 3"Volume of cement reqired 1.5 bagsCost of cement @ 375Tk/bag 563Labour 900

Sub‐total 1463

3 Concrete stump ('kaatla')No. required 14Total cost @ 140Tk/stump (incl 2no. 3/8" screws per kaatla) 1960Labour for making kaatla 200Labour for fixing in ground 200

Sub‐total 2360

4 Posts 15 no.Average length required 8', assume 1 culm gives 2 posts 8 culmsCost of 1no. 3‐4" dia culm (Borobas) 220 TkTotal cost 1760Labour to fix to kaatla & posts 200

Sub‐total 1960

5 Cross bracing & wall plates5no. walls cross braced, approx length 11.5 ftBamboo req. @ 2no. piece per culm, 220Tk ea 3 no. 6606" nails for cross bracing joints 40 pc. 75Bamboo for wall plates, approx length 16ft, maklabas @ 160Tk/ea 6 no. 640Labour 800Nylon string for all bamboo nailed joints, 2kg 175

Sub‐total 2350

6 Roof frameUse 'maklabas' bamboo dia 2‐3", spacing @ 2ft 3in c/cBamboo required, assume 22ft usable length per culm 8 no. 1280Labour to fix rafters 400

Purlins, use 'goranime' timber, 2"x1" @ 420Tk/cuft, total length 250ft 3.5 cuft 1470Labour to fix purlins 400Nails to fix purlins to rafters 220

Side roof, length 10ft, make using bamboo and recycled CI sheetBamboo required 1 no 160

Sub‐total 3930

7 Roof sheetUse 0.26mm thick CI sheet @ 4800Tk per 72ft x2.5ft (1no. 'ban')Length of roof spans = 8ft + 7ft + 7ft 22 ftWidth 18ft 8 sheetsTotal length 176 ft 11733Ridge plate, 18ft length 560Roofing nails 500Labour to fix roof sheets 400

Cost budget breakdown for typical single storey house rev 2 06.07.11

Sub‐total 13193

8 WallsExternal walls to have 3no. rails to support windows and wall cladding 192 ftBamboo req, use 1‐2"dia 'maklabas' bamboo @ 160/Tk ea, assume 18ft usable length 11 no. 1760

Louver, made with 8no. bamboo strip or 'bata', total length required = (2x16') + (2x10') 52 ftBamboo req, assume that 1no. bamboo gives 8no. strips 18ft long. 3 no. 480Labour to fix louvers 400

Lower part of external wall use recycled CI sheet 0Labour to fix rails and CI sheet 200

Assume recycled CI sheet will be used on walls where possible, assume area of 150 sqftCI sheet walls fixed with horizontal bamboo strip at 2ft c/c, length of strip required 200 ftBamboo req, assume that 1no. bamboo gives 8no. strips 18ft long. 1.4 no. 160Tying wire 400Labour, assume 2 men can fix 240sqft in 1 day 250

Remaining area of internal and external walls to be constructed with bamboo mat ('bera') 280 sqftUse bamboo strips or 'bata' at 1 ft c/c on both sides of mat in a grid pattern 1220 ftBamboo req, assume that 1no. bamboo gives 8no. strips 18ft long. 9 no. 1440Cost of bamboo mat, @ 150Tk for 4'6" x 6' sheet 11 no. 1650Labour to fix walls, assume 2 men can make and fix 100 sqft in one day 1120

Sub‐total 7860

9 Borax treatment@ 1Tk per 1ft bamboo, based on vertical soak diffussion method, reusing borax solution 4 times. Total culms (25') 51Total length to be treated 1274 ft 1274Assume labour undertaken by household 0

Sub‐total 1274

10 Doors and windows ‐ basic optionRecycle 1no. door, make 1 new. Use mango wood @450 Tk/cuft 0.4 cuft 180Labour 400

Windows ‐ use bamboo and recycled CI sheetBamboo required 1 no. 440Labour 600

Hinges and nails etc 100

Sub‐total 1720

Total costs 31419 7090 38509Cost per square foot 150 Tk/sqft

Extras costs to improve the finish of the house ‐ make it stand outPaint & brushes for lower CI sheet panels 250 200

Extra bamboo for trims and finishes 3 no. 480

Windows and doors ‐ extra costs for expensive optionExtra bamboo for bamboo strip cladding 6 no. 960Window and door timber, use mango wood @ 450Tk/cuft 1.7 cuft 765Locking chains for doors 160Hinges and nails etc 330Labour for making and fitting 1200

Ladder for access for drying popodoms and access to roofBamboo required 1 no. 220Labour 200

Bamboo frame for roof climbing plantsBamboo required 3 no. 480Labour 400

Plants 500Labour to contruct flower bed 400

Sub‐total 6545

Total costs 4145 2400 6545

Total cost including extra costs 35564 9490 45054Cost per square foot 176 Tk/sqft

Appendix C - Breakdown of costs 2 storey house (Rubi and Fahima’s)

No detailed bill of quantities has been produced but a typical cross section of this house given in

Appendix B – “Sketch of cross section of Rubi & Shabitribala’s house looking east” (house on the

right hand side of page)

Costs include labour and materials only and do not include overheads and management costs of

SAFE.

The floor area of each house is 12’ x 17’ downstairs and 12’ x 15’ upstairs. Total floor area = 384

sqft.

Total cost per house = Tk 39,575 per house

Total cost per sqft = 39,575/384 = 103 Tk/sqft or $1.25 sqft

Note: Costs below are for 2 houses

Job 100 Rubi and Fahima's House

101 Katla BDT 4,379

102 Treated Bamboo (131 pc) BDT 22,308

103 Floor BDT 1,800

104 CI Sheet BDT 12,318

105 Bamboo Matt BDT 1,450

106 Wood/Purlin BDT 1,389

107 Bolts/Others BDT 4,980

150 Labour BDT 29,185

170 Materials Transport BDT 1,339

Total Monthly Expenditure

Total Expenditure BDT 79,148

Appendix D

Field tests of bolted bamboo connections

Improvised field testing of bolted

bamboo connections for use in bracing

of informal housing. 15 June 2012

Samuel G Stephens BE (Hons)

Structural Engineer

SAFE (NGO) Bangladesh

Abstract Improvised field testing was carried out to ascertain a reasonable strength value for bolted bamboo

connections used in the cross-bracing of informal housing.

A single connection strength of 3.9kN was determined (which includes a 0.60 safety factor for

variations in materials and construction) provided that the following requirements are met;

• All cross-bracing members must terminate in a node (a 'node' is a naturally occurring,

regular spaced thickening present in bamboo).

• The end distance between the bolt and the end of the cross-bracing member must not be

less than 2" (51mm)

• The minimum wall thickness of bamboo to be used as a cross-bracing member is to be 3/4"

(19mm)

• The minimum outer diameter of bamboo to be used as a cross-bracing member is to be 2.5"

(63mm)

Further testing is required to confirm these results.

DISCLAIMER:

The following report and all its recommendations are to be used for

informative purposes only. The Author and SAFE (NGO) Bangladesh take no

responsibility for damage to property or life resulting from this report being

used for anything other than its intended purpose.

The following does not purport to be a scientific or definitive document. Field

testing was carried out in an improvised manner to provide at least some

Engineering basis for the improvement of low-cost housing construction in

Bangladesh.

2

Contents

Abstract ................................................................................................................................................... 1

1. Introduction .................................................................................................................................... 3

2. Materials and methods ................................................................................................................... 3

3. As-built cross-bracing survey .......................................................................................................... 5

4. Results ............................................................................................................................................. 5

5. Findings ........................................................................................................................................... 7

a. Initial ........................................................................................................................................... 7

b. Load Capacity ............................................................................................................................. 7

6. Discussion ........................................................................................................................................ 7

a. Suitability of Load Capacity ......................................................................................................... 7

b. Guidelines for construction......................................................................................................... 8

c. Other possible failure mechanisms............................................................................................. 8

i. Receiving member (bamboo beam or post) failure due to splitting. ..................................... 8

ii. Foundations ............................................................................................................................ 9

iii. Tension failure of bamboo brace .............................................................................................. 9

7. Knowledge dissemination ............................................................................................................... 9

8. Literature cited ................................................................................................................................ 9

Appendix A (As-built Survey) ............................................................................................................... 10

Appendix B (Test Data) ......................................................................................................................... 12

3

1. Introduction

SAFE (NGO) works in improvement low-cost housing in Bangladesh. Working primarily in Bamboo,

SAFE strives to build stronger and longer lasting houses for low-income families.

High-winds are one of the biggest hazards for housing in Bangladesh. SAFE has been providing

bamboo cross-bracing to its bamboo framed houses to provide lateral stability. Testing of these

bamboo bracing connections was undertaken, along with Structural Engineering Design Calculations,

to provide an Engineering basis for future design and implementation.

2. Materials and methods

Bracing bays are provided (as shown in figure 1) to every external wall, no more than 12' (3660mm)

apart. Two sets of bracing are used (on either side of the posts) if the wall is shared between two

houses or rooms.

Figure 1 Typical Bracing Bay

Half bamboo members are used to provide tension-only cross bracing. These half bamboo cross-

braces are fixed to vertical bamboo posts or beams using M10 bolts and 32mm circular washers to

construct bracing bays.

By inspection, it was hypothesized that the weakest part of the bracing system would be this bolted

connection between the cross brace and the post or beam (figure 2).

The bamboo used in testing was of the same species, from the same cultivation area and had

undergone the same treatment process as the bamboo used in SAFE construction.

4

It was expected that the connection would fail in a 'pull out' mode, which is to say that Bolt A would

pull out the end of the bamboo cross-brace. This hypothesis was reached because of;

• the small edge distance between the bolt and the end of the cross brace in the direction of

loading.

• the high strength of the bolt compared to the bamboo.

• the much larger size of the full-bamboo post/beam when compared to the half-bamboo

cross brace.

From conventional timber Engineering knowledge (which, as another naturally occurring, cellular

material can be considered a reasonable comparison) it was assumed that the wall thickness of the

test specimen would have a greater effect on its resistance to bolt pull out (and therefore strength)

than the outer diameter of the test specimen.

To best test this connection, it was devised to suspend an idealised connection or test specimen

(figure 3) from a frame (figure 4) with a known weight attached. Weight and therefore force on the

test connection would then be gradually increased until the connection failed.

Figure 2 in-situ bracing connection Figure 3 test specimen

Figure 4 testing rig

Picture 1 testing rig in use

5

3. As-built cross-bracing survey

A survey was undertaken of completed SAFE demonstration houses to ascertain the section

properties of as-built cross-bracing.

Summary of findings

all values in mm

min max average

end distance 30 150 73.8

brace diameter 57 75 63.8

brace wall thickness 9 18 13.5

The results of the survey show large variations in the size and wall thickness of cross-bracing

members as well as end distance.

27% of braces were found to not terminate at a node.

Full survey results can be found in Appendix B.

4. Results

Due to time constraints and the limitations of working in rural Bangladesh, the testing was beset by

problems with the testing equipment. In all, 13 tests were undertaken though only three can be said

to have been completed successfully.

Succesful tests

Wall (mm) Ult. Load (kN) Reason for invalidation

Test B3 10 8.13

Test C 11 6.48

Test E 14 8.17

Invalid Tests

Test Ai 15 0.9 craddle reached ground

Test Bi 9 2.09 additional weight required

Test Ci 13 3.52 loading hook failed

Test A 15 1.04 loading hook failed

Test A2 15 2.82 ropes slipped

Test A3 15 7.62 beam failed

Test B1 10 4.72 bolt rotation in beam

Test B2 10 3.95 beam rotation

Test D 11 4.98 loading bolt b pullout

Test F 11 7.22 beam failure

The sample size is too small to give a scientific indication of joint performance but further testing is

not possible at this time.

6

Picture 2 above shows a typical test specimen under load. Picture 3 shows the same specimen after

it has failed due to Bolt A 'pulling out' through the end of the half bamboo test specimen.

Nodes are visible at both ends of the test specimen.

Full testing results can be found in Appendix B.

8.13

6.48

8.17

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

8 10 12 14 16

fail

ure

lo

ad

(k

N)

test specimen wall thickness (mm)

Bolted Bamboo Connection Testing

Results

Succesful tests

Invalid Tests

Picture 2 test B3 under load Picture 3 test B3 after failure

7

5. Findings

a. Initial

Initial testing was fraught with equipment failure though some early assumptions were quickly

confirmed. Namely;

I. End distance (the spacing between the bolt and the end of the bamboo cross-brace in

the direction of the load) has a significant impact on its load carrying capacity. From

initial testing, it was decided that a 2" (51mm) minimum end distance would give

significant additional capacity whilst still being reasonable to construct (greater end

distances are sometimes not feasible due to conflict with door openings and other

framing members).

II. Nodes. Bamboo has naturally occurring thickenings along its length from which shoots

and leaves grow, known as nodes. These nodes are substantially thicker than the rest of

the bamboo and also have a disrupted grain pattern. These physical characteristics

provide an increased strength and resistance to bolt pull-out at the end of the bracing

members. Therefore, all bracing members will be terminated at a node.

b. Load Capacity

Using the limited test data available, a bolted connection strength has been reached by the following

rationale;

• The lower-bound of successful tests was 6.48kN

• A connection safety factor (∅) of 0.60 is deemed appropriate due to the uncontrolled nature

of Bangladeshi construction, variability of materials and uncertainty due to the small testing

sample size.

�� =��, �� × ∅��

�� = 6.48�� × 0.60

� !"#$% = &. '()

6. Discussion

a. Suitability of Load Capacity

From 5. b. (above), a load capacity of 3.9kN has been ascertained for a single connection (including a

0.60 safety factor for connections).

From structural analysis, it has been calculated that the likely (un-factored) force on this connection

during wind loading is 2.32kN.

3.9

2.32= 1.68 ≥ 1.50012345674879:6;< ∴ ok

8

The value of 2.3kN has been determined from a design wind speed of 139km/h (35.5m/s). This design

wind speed is based on the following conditions of IS 875:198722;

47m/s Basic Wind Speed

25 year design life

terrain category three

flat topography

b. Guidelines for construction

From testing results and consideration of construction realities, the following parameters will be set

for the construction of bamboo cross bracing;

• All cross-bracing members must terminate in a node.

• The end distance between the bolt and the end of the cross-bracing member must not be

less than 2" (51mm)

• The minimum wall thickness of bamboo to be used as a cross-bracing member is to be 3/4"

(19mm)

• The minimum outer diameter of bamboo to be used as a cross-bracing member is to be 2.5"

(63mm)

The minimum wall thickness prescribed above is significantly thicker than any used in testing. From

experience, the use of thicker walled bracing will be achievable in practice and this will allow for

some additional load capacity above that stated in this report.

c. Other possible failure mechanisms

i. Receiving member (bamboo beam or post) failure due to splitting.

During testing, failures were observed where Test Bolt A would rotate within the test beam resulting

in the beam cracking longitudinally (picture 2).

The testing involved the beam being loaded

perpendicular to the grain (the weakest

direction). In practice, the cross-brace will be

placed at a 45⁰ angle and, therefore, the

beam/post will be loaded at 45⁰ to the grain (as

opposed to 90⁰ during the test). Studies have

shown that bamboo's compressive strength is in

the order of 4 times stronger in the direction of

the grain (0⁰) than perpendicular to it (90⁰)1.

Therefore, it follows that an increased strength

magnitude of 2 could be reasonably assumed for

loading at 45⁰ and applied to the testing results.

From the two tests that failed due to bolt

rotation and beam splitting (Test B1 and B2) the

lowest strength ascertained was 3.95kN.

However, this was using the same beam that had

already split in test B1 where it achieved a load of 4.72kN and this would be a more accurate

representation of the beams resistance to splitting. If a factor of 2 is applied to 4.72kN, a probable

resistance of 9.44kN is found which is significantly higher than the lower-bound of 6.48kN used in

the load capacity calculations pertaining to pull-out failure. Therefore this failure mechanism is

assumed not to govern.

Picture 4 bolt rotation and cracking of test beam

9

ii. Foundations

After considering results of the bolted connection testing, it is now probable that the foundations

(pre-cast concrete piles known as kaatlas) will govern the bracing design. However, design and

testing of these kaatlas is outside the scope of this report.

iii. Tension failure of bamboo brace

Tension failure of the half bamboo cross-brace itself is not expected to govern as this would have

become apparent during tests. A short section of bamboo connected test bolt A from loading bolt B

and would have served to test the bamboo tensile strength at the same time as testing bolt A.

7. Knowledge dissemination

Findings from this testing will/have be actioned in three areas;

• Structural drawings have been produced showing minimum dimensions and construction

details of bracing for use in future SAFE projects.

• This report will be made publicly available on the SAFE website.

• A leaflet (in Bangla) has been produced and distributed to slum residents outlining

construction requirements for cross-bracing. Refer to Figure 3 below for segment pertaining

to dimensions of cross-bracing. The complete leaflet as well as an English draft can be found

on the SAFE website (http://safebangladesh.wordpress.com)

Figure 3 section of Bangla cross-bracing leaflet

8. Literature cited 1. Mechanical and Physico-Chemical Properties of Bamboos carried out by Aerospace Engineering

Department, Indian Institute of Technology – Bombay with Prof. NK Naik as Principal Investigator.

Retrieved 16th June 2012 from http://www.bambootech.org/files/mechanicaltesting%20report.pdf

2. IS 875:19872. Indian Standard Code of practice for design loads (other than earthquake) For

buildings and structures. Part 3 Wind Loads (Second Revision)

10

Appendix A (As-built Survey)

11

12

Appendix B (Test Data)

13

14

15

Appendix E

Simple guidelines for cross-bracing - leaflet

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2” (50mm

)

2 © © (50 wgwj wgUvi)

CONSULTING ENGINEERS

2.5” (63mm

)

2.5 © © ( 63 wgwj wgUvi) 3/4” (19m

m)

3/4 © © (19 wgwj wgUvi)

SAFE

CROSS-BRACING

By adding half pieces of bamboo cross bracing to your walls as outlined below,

you’re house will be stronger and resist high winds, storms and earthquakes.

SAFE

SAFE Bangladesh guidelines for

better-building with Bamboo!

Easy steps to help your house resist

wind, earthquake, rain, last longer

and save you Taka!

��

��

�� ! �� ! ��

�প��

Where should I place cross-bracing?

Cross-bracing should be added to EVERY external wall of your house. These walls should

be no more than 12” apart. If they are, a middle wall will need to be braced TWICE. If

house is two-stories, top story bracing should be placed directly above the bracing below.

SAFE

�� !

HANDY TIPS

• Use bamboo treated against insect attack for longer lasting house (contact SAFE for more in-

formation)

• Protect cross-bracing and all bamboo from rain and wind using CI sheet and careful planning.

• Use concrete Katla foundation pads to prevent bamboo posts from rotting in the earth.

• Mixing 5% cement with mud plaster will make walls and floor last MUCH longer.

(more tips in Bangla RE: Maintenance)

How do I connect the bracing?

A drill and M16 bolt with washer is required to con-

nect each end of the cross bracing. You must be

careful to have a node at the end of each cross brace

and also have a minimum of 2” (50mm) from the

bolt to the end of the cross brace. Connections are

THE most important part of cross bracing

What Bamboo should I use?

Thicker bamboo is best but size should be at least

2.5” diameter and 3/4” wall thickness as shown on

below;

Roof Bracing

Roof bracing is another easy way to

strengthen your house. Add diagonal bamboo

members to the corners at the top of your walls

and fix with bamboo nails.

MORE INFORMATION

SAFE Bangladesh promotes improved building techniques for low-cost housing in Bangladesh. By

doing this, we help Bangladeshi’s build better and longer lasting houses, with their own hands!

SAFE demonstration houses can be viewed in Jorgen Babur Mart, Dinajpur where you can see all

of these techniques in action.

If you have any questions, contact;

Azit Roy xxxxxxxxxxxxxxxx

Pulin Roy xxxxxxxxxxxxxxxx

Masud xxxxxxxxxxxxxxxx SAFE

2” (50mm

)

2.5” (63mm

)

3/4” (19m

m)

Appendix F

Solar light bulb installation report

S. G. Stephens BE (Hons) 1

June 2012

M E M O R A N D U M O N I N I T I A L T R I A L O F S O L A R

B O T T L E B U L B I N J O R G E N B A B U R M A R T S L U M ,

D I N A J P U R , B A N G L A D E S H

Prepared by S. G. Stephens 7th June 2012 for SAFE Bangladesh (NGO)

Pictures and video by Marianne Keating

INTRODUCTION

SAFE Bangladesh is a small NGO working primarily in the low-cost housing sector in North West

Bangladesh. As part of their work improving quality of life through improved building techniques, SAFE

has started to experiment with using water-filled plastic bottles to provide low-heat and electricity-free

lighting.

OVERVIEW OF INTIAL TRIAL

Intial trial bulb was installed 6th June 2012, at the house of local slum builder Delowar. As this was an

initial trial, bulb was placed near wall where it would be less-effective but where it could be placed

through a small section of rather tired corrugated iron (CI) sheet that could be easily replaced.

A 2L coke bottle was filled with a mix of boiled water and approximately 250ml of Clorox liquid bleach

purchased in Dhaka. Bangladeshi bleach seems to be far weaker than the equivalent in the UK. The bottle

of Clorox states an active ingredient (Sodium Hypochlorite) concentration of >5,25%. Taking the label at

its word, the bottle bulb should contain approximately 6.5ml of Sodium Hypochlorite per liter.

The bulb was initially placed and sealed into a small 500x500 section (or 'patch') of CI sheet using McCoy

General Purpose Acetoxy Silione Sealent purchased from a glaziers in Dinajpur. After curing, a hole was cut

in the roofing CI sheet and the bottle and 'patch' sealed on top.

PHOTOS

Bottle and CI sheet 'patch' before sealing Cutting hole in roofing sheet


June 2012

Sealing between patch and roof sheeting Placement

INTIAL COST ESTIMATE

Intial Cost Estimate of Solar Bottle Bulb

In Dinajpur, Bangladesh (June 2012)

Item Cost No. Bulbs Cost/Item

Silicone applicator gun BDT 400 ignored

Tin Shears BDT 100 ignored

2nd hand plastic bottle BDT 10 1 BDT 10

Silicone 280ml tube BDT 250 2 BDT 125

Bleach (1L 5.25% NaOCl) BDT 210 4 BDT 53

CI sheet 'patch' BDT 500 10 BDT 50

BDT 238

238BDT/bulb is possibly too expensive for the Solar Bottle Bulb to be widely adopted in JBM slum.

The following areas could produce savings in the cost of each bulb;

1. Finding a cheaper silicone or sealant, possibly in bulk with a brush application. Important

qualities for the sealent are; elastic, bonds to steel and plastic and resistant to water, sun and

elevated temperatures.

2. Finding a cheaper and locally sourced bleach. 'Bleaching powder' was found in Dinajpur though

this powder had only very week concentrations of Chlorine and was cut with an insoluble

powder that would make the bulb ineffective. Bleach needs to be found with as little colouring as

possible, the Clorox used in the test has a slight yellow tinge which coloured the bulb.

3. Using second hand CI sheet to form the patches. This was done for the initial test bulb though it is

hard to discern a cost for such a second hand item and new CI sheet prices are used in the

calculation above.


June 2012

RESULTS

Once placed, the bulb was very bright and provided a large amount of light into the previously very dark

room. Please refer to http://youtu.be/rlS17jVZ6s0 for a visual demonstration of effectiveness.

The installation will be monitored over the upcoming Bangladesh rainy-season to evaluate effectiveness

and durability of sealing system used.

Room interior with Solar Bottle Bulb covered

Room interior with Solar Bottle Bulb un-covered


June 2012

COMPARISSON TO OTHER LIGHTING ALTERNATIVES

CLEAR PLASTIC CI SHEET

One strip or even a short section of clear plastic corrugated sheet provides large amounts of light into a

room. A 7' sheet costs 700BDT which is approximately 1.5times the cost of the thick CI it replaces. So, this

is not inordinately expensive yet there is not one house in the slum where this has been used.

Possible reasons for the clear plastic sheet not being adopted are;

• Heat. A small, 1'x2' section of the plastic sheet was installed in a SAFE demonstration house and

provided a lot of light though the owner complained about the heat.

• Frailty and durability. The plastic sheeting is seen to be weaker than the CI sheet it replaces and is

likely to get dirty.

Comparing cost;

A 2'4" x 2'6" clear plastic corrugated sheet suitable to make a skylight costs about 233BDT which

is comparable with the 238BDT it cost for the initial trial solar bottle bulb.

It is hoped that the cost of the bottle bulb can be significantly reduced and that it performs better

that the plastic corrugated sheeting in terms of heat and durability therefore making the solar

bottle bulb a viable alternative.

ELECTRIC BULB

Almost all the houses in the slum use at least one electric bulb, sometimes through an illicit connection.

The electric bulb works at night while the solar bulb obviously won't. This disadvantage is somewhat

mitigated by the fact that the electricity supply is very intermittent. During peak irrigation season, rural

areas of Dinajpur can receive as little as a few hours of electricity each day while the sun shines almost

perpetually.

Comparing cost;

From a recent electricity bill, the current price of electricity in Dinajpur appears to be

4.2BDT/kWh (1/6th of the price in the UK).

Assuming a 50watt bulb is used for 6 hours each day;

0.060� × 6ℎ × 4.2��

�ℎ= 1.512

��

��

At the initial solar bottle bulb cost of 238BDT, the payback period is about 5½months.

It is hoped that, by reducing the cost of the solar bottle bulb, the pay-back period can be reduced

and the financial advantage increased.

The cost of a traditional tungsten filament bulb is only 22BDT. If we consider a 5watt energy-

saver bulb, the pay-back period jumps to over 5years. However, the initial cost of an energy saver

bulb is approximately 250BDT and therefore more expensive than the solar bottle bulb. An

energy-saver bulb will also be susceptible to the sporadic electricity supply.


June 2012

LESSONS LEARNED AND KNOWLEDGE GAINED

1. Bulb is effective yet expensive (≈240BDT). Steps described earlier in 'Initial Cost Estimate' could

significantly decrease cost and improve likelihood of technique being adopted.

2. A cheaper and possibly simpler form of sealant needs to be found locally.

3. A cheaper and possibly 'clearer' bleach or disinfectant needs to be found locally.

4. Monitoring and experimentation is required to see which concentrations of which

bleaches/disinfectants are most effective and affordable.

5. It is important to use good quality CI sheet for the patch as well as select a good piece of receiving

CI sheet on the roof. This is because worn CI sheet can have a less-pronounced or deformed

corrugation profile and therefore be difficult to seal.

6. It is important to center both the hole in the patch and the hole in the receiving sheet to the same

orientation of the corrugations. i.e. a corrugation ridge should correspond to the centerline of

both the hole in the patch and the receiving sheet.

7. Financial and other advantages of these bulbs are currently not very convincing to slum

residents. Further study is required to produce a stronger case to submit as to "why?" they should

install a solar bottle bulb.

LONG-TERM VISION

It is hoped that one or more of the local Jorgen Babur Mart slum builders (Delowar, Masud or Baush) can

be trained how to install solar light bottles and do so for a reasonable price while earning some money

for themselves. In short, to create a small entrepreneurial business to provide improved lighting

throughout the slum.

Appendix G

Location key plan of households & interview of household

Shujon Chandra Dash

Shujon going to work wife mum wife growing vegetable Shujon Chandra Dash:

Shujon is the youngest son of Durgoty Das and Zudhishti Chandra Dash. He has 2 sisters and 2 brothers. All his siblings have now moved away and Shujon lives here with his wife, 2 young children and his mum and dad. Shujon works as a day labourer for pond owners outside Dinajpur who farm fish. His work involves catching the fish, maintaining the nets (often involves diving 20-25 ft to the bottom) and cleaning the water. In off season he repairs hemp sacks (bosti). The daily wage he gets from the fish farm varies from 40 taka ($0.5) to 300 taka ($3.5) but on average he will earn $ 35-40 per month. From this, and the income that his wife earns from rolling poppodoms, they support their family and also his aged parents.

His dad is partially sighted and though he does look old he does not look the 101 years that Shujon claims! In January 2012, his father suddenly went missing. The whole family searched all over – the neighbourhood first, then the whole town. Exasperated, they went to seek the advice of fortune tellers. The first advised that he might have gone to Dhaka and so Shujon made the journey and visited friends in the capital but his dad was not to be found. The second

fortune teller advised him that his dad was " in a place from where if was difficult to come back to Bangladesh". On month later, news reached Shujon that his father had been found at his sister’s house in India. Without telling anyone, and without any papers or money, he had managed to cross the border in India, was arrested by the border police and kept in jail for 12 days. Finally the police took pity on his and let him go – one even gave him 150 taka. And so he managed to make his way to his sisters house.

Giribala:

daily allowance in the form of breakfast and lunch. In the one-hour evening shift, she does almost the same amount of work, but does not get any allowance in the form of food. She is living with her daughter, who is about to get married. The new house will increase social value for her daughter's marriage.

Giribala has one son and one daughter and is in her late 50s. Her son stays in Dhaka where he earns money as a rickshaw puller – he can earn much better money there. Giribala works as maid in two houses. Each day she will spend two-hour morning shift for washing clothes, cleaning the floor in a 4-room house. She cuts the vegetables and does all the food preparation before the cooking begins. As a monthly wage, she get 350 taka ($5) from each of the houses, including a

Surujban:

Shurujban Son

After the 1971 Liberation War, Surujban came to stay in Jorgen Babu Marth, from Gaibandha district and started staying rental houses surrounding the field. Her main livelihood is making poppodoms. In the first step, the vendors give the balls of raw dough and she rolls them and lets them dry under the sun. In the second step, she has to repeat the whole process again to make the poppodom thinner and wider. In the dry season, she makes 500 poppodom for 50 taka ($0.60) per day. Her son and daughter-in-law earns 200 to 300 taka in off-season (rainy season) and approx 500 taka per day as brick layers during the construction season. They rent out their three-wheeler rickshaw ‘van’.

Surujban has the intention of saving so with the money she saved from her per diem from the SAFE Workshop, she brought a goat. The goat is now pregnant and she hopes to get two to three baby goats a year which she can sell.

Saidul Rahman:

Saidul Rahman, an Ice-cream vendor in his early 50s has got two daughter and a son. In the winter season, he collects recycling material from door to door in the exchange of his peanuts & pickle. He also sells ice cream around the local area. He works weekly four-to five days a week and earns around 250 taka ($3.00) per day. His eldest daughter got married at the age of 12. He says that if his daughter remained single beyond this age then there might be problems – like she may have an affair. His other daughter, Shathi, is of sixteen years old and is disabled. Shathi was a normal child at birth with only a little working disability with her left hand, but at the age of nine month, was attacked by severe fever which made her lose her vision and left difficulty in her hearing. Over the years, she did regain her vision, but she never learnt to talk. She could still walk holding walls, doors and other kinds of vertical supports, but three years ago she had a severe road accident which took her ability to walk even. All of her family members including her younger brother have to feed her meals three times a day. Sometimes when all the family members are out to work, they tie her leg to the bed stands with rope, so that she does not go crawling around, getting herself hurt. A local NGO has given Shathi a wheelchair to help her become more mobile.

Rubi Begum:

\

Rubi Begum came to Dinajpur after the Liberation War of 1971. She is Muslim. She got married at the age of 13 and had a 9‐years of married life before she became widow with a 2 1/2 year old son and was pregnant with her daughter. Soon enormous pressure was exerted on her to get married again and so she ran away from her home in Gaibanda leaving her son to be looked after by her mother.

She worked as a maid for the first year, and then started to work as a day‐labourer, doing jobs in construction work, earth excavation, and at the rice mill factory.

As she was young, it became really hard for her to work due to indecent verbal abuse from her male co‐workers. She left these jobs and started selling door‐to door glass‐bangles, laces and necklaces. (Her Hindu neighbour sold bangles previously and taught her) Still is still doing this vendor work. She never gave up the fight and says her children were her inspiration to keep‐going in her life.

Her daughter and son‐in‐law stay with her, and two grandchildren. In this new two‐storey house, she has now some space of her own to pray, do her vegetable gardening, as well as dry to poppodom in a hygienic way (i.e not in the street) on the verandah.

Shabitribala

Shabitribala walks with difficulty following and earlier accident but she still works as maid. Shujon, son of Shabitribala, got married recently with a handsome dowry and is happy that he can use some of this money so that he may be able to help his sister into a good marriage. During the off‐season (rainy season), he repair's hessian sacks used for rice and other agricultural produce. During the dry season, he does fishing for the local pond owners earning 3000 to 4000 ($35‐$40)taka per month.

This new house has allowed enough space for all kinds of functions including a room for Shabitribala, one for Shujon and his wife, a prayer space and vegetable gardening.

Dhirinchondro Ray was the actual owner of this land and house for the last ten years. Shabitribala was his wife's younger sister who has been living with them ever since she became a widow.

Shabitribala has a one son and one daughter.

Before the construction of this new demonstration house started Dhirinchondro Roy’s wife, Rongobala died suddenly. Couple of months later, after the new house was about to be finished, Dhirinchondro ran away to Dhaka to re‐marry another elderly lady from Dinajpur. He left this house to Shabitribala and her children.

Beauty:

Beauty got married in her early teens and she moved with him to Dhaka. She says that a month after arriving in Dhaka she realized that her husband was trying to sell her off to sleep with other men. With the help of her cousin, she escaped from Dhaka and came back to mother's home in Dinajpur. Her parents didn't believe her. When husband came back, he convinced her family that everything was fine and stayed with them for two to three months, after which she fell pregnant with their first child. He then fled for 4 years without any trace. When he came back again, he told that he has been in prison all these years but was now a changed man, and Beauty again took him in. Unfortunately after 2.5 years he left again, this time for good and without a trace, leaving her pregnant with her second son, Akash (sky). During this period she earned her living from a variety of jobs including breaking bricks on construction sites and cleaning govt. drains.

Due to social pressure, she had to remarry again and had a third son, Prem. This man was also unfaithful to her and when his activities got exposed he also left Beauty for good.

Beauty with her two elder sons together earns about $5.00 per day. The two eldest sons stopped school so they could work to earn money for their mum. They work repairing jute sacks while Beauty now earns her living by selling deep fried snacks around the neighborhoods.

Nurjahan:

Nurjahan got married when she was very young. She had two daughters and then her husband fell very ill. After suffering severely for couple of years, the illness at last took its toll and he passed away. Money was short and she didn’t even have enough money to pay for the funeral. As a widow she has found it difficult to earn money and she moved back to her father's house with her daughters. Within a few years her father also died and it was not possible for her to stay with her step‐mothers family.

At certain time, Nurjahan started to beg around Dinajpur town. Later on, she became a day labor for quite a long time. Now she works as maid at some households and earns 600 taka ( $7) per month as well as some food from the houses.

Bhagaboti:

Bhogoboty got married around 30 years back witt Atul Proshad Roy when she was 23. After 10 years of her mariage her Atul got married with Bhogobotie's younder sister and all stayed together in the same family for 12 years. Even though B didn’t like Bhogoboty has got one son and three daughters and her sister has got one son and a daughter. Bhogoboty stays with her son now as and her hunsband comes to visit some times as he went to another house eight years back to stay with his younger wife. Bhogoboti cannot stop comming of her husband as their son requested that how can they deny the person who has given birth of them.

She was involved in workshops of diffent ngos. She takes small loans from the N.G.O.s and buys clothes like saree and lungi from the retail market and sells to door to door as her profession. A monthly 2500 taka ($30) is her average income from this. She feels like at least she is not totally dependend on someone. Her son giot married at the age of 16. He stays at the same house with his wife. He works as sales man in a auto flower mill earning 3500 taka ($ 42) per month.

Bhogoboty loves groing vegetables and plants. Wherever she could, she grew lots of vegeables. She also does three times prayer everyday in her praying space with hidu daities and their pictures.

Appendix H

3-day design workshop programme

11.05.11/JA

Simple Action For the Environment (SAFE)

Design Workshop – Jorgen Babur Mart community, Dinajpur, 15-17th May 2010

3 day design workshop with 10 members of the community of Jorgen Babur Mart, architects,

engineers, carpenters and builders. Objectives: to build trust between partners; learn about

building-for-safety techniques appropriate to the context of Jargon Babur Mart, develop designs

for our proposed houses within a specific budget; produce an outline plan for construction.

15.05.11 Day 1 –Existing good practice

10:00 – 10:30 Introduction – getting to know each other.

Objectives (see above)

Activity – each household draws their house on the map.

SAFE – about us

10:30 – 13:30 What is a hazard? What is a disaster?

Activities – brainstorm different hazards and then in groups think of ways to design your houses to overcome them. Followed by short presentation by groups on their findings.

13:30 – 14:30 Lunch

Good practices of resilient low-cost housing in Bangladesh, relevant to Jorgen Babur Mart context. Including

Bamboo treatment Lighting and ventilation – windows; natural ventilation; improved

cook stove Stronger frame – improved bamboo joints; cross-bracing;

concrete foundation posts (kaatla) Walling materials and heat Cement stabilisation for earthen plinth Growing vegetables

16.05.11 Day 2 – Initial design

10:00 – 10:30 Welcome and review of good practices from yesterday afternoon. Objectives for today.

10:30 – 13:30 Design house for Jorgen Babu Mart (2 groups).

Activities include:

Presentation by architect students to groups about initial designs. Model building Groups to focus on different sized houses

13:30 – 14:30 Lunch

14.30 – 16:15 Continue to develop design, incl. cost analysis of each house option (2 groups)

16:15 – 17:00 Informal presentation from each group about each house option

17.05.11 Day 3 – Design review and implementation

10:00 – 10:30 Welcome, objectives for today.

10:30 – 12:30 Design development including revisions with respect to costs.

10:30 – 12:30 Singing with song team

12:30 – 13:30 Presentation about each house option including costs.

13:30 – 14:30 Lunch

14.30 – 16:30 Implementation and management

16:30 – close Certificate award ceremony

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