STUDY OF RURAL HOUSING IN MAMBA DISTRICT KILIMANJARO, TANZANIA - EXAMENSARBETE 2009
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STUDY OF RURAL HOUSING IN MAMBA
DISTRICT KILIMANJARO, TANZANIA
Jenny Mattsson
EXAMENSARBETE 2009
BYGGNADSTEKNIK
STUDY OF RURAL HOUSING IN MAMBA
DISTRICT KILIMANJARO, TANZANIA
STUDIE AV BOSTADSBYGGANDE PÅ LANDSBYGDEN
I DISTRIKTET MAMBA KILIMANJARO, TANZANIA
Jenny Mattsson
This thesis project is written at the School of Engineering Jönköping
University in the field of building technology. The work is the final part of
the three-year programme Bachelor of Science in Civil Engineering. The
author is responsible for expressed views, conclusions and results.
Supervisor: Bernth Jirvén
Credit points: 15 ECTS (C-level)
Date: 09-06-02
Arkiveringsnummer:
Postadress: Besöksadress: Telefon:
Box 1026 Gjuterigatan 5 036-10 10 00 (vx)
551 11 Jönköping
Preface
Preface
This study has been carried out with support from SIDA (Swedish International
Development Cooperation Agency) and the Minor Field Study scholarship.
Anita and Reines Rydell made it possible for me to accomplish the study by taking me
as their guest. They made my stay in Tanzania a memory for life.
Reines has made a great work as my supervisor on site and generously shared his
knowledge and experiences.
Bernth Jirvén has been my supportive supervisor at School of Engineering, Jönköping
University.
I would like to thank above mentioned persons for their engagement and participation
in this study.
Jönköping June 2, 2009
Jenny Mattsson
Abstract in Swedish
Abstract in Swedish
Som ett av de fattigaste länderna i världen står Tanzania inför en ekonomisk
problematik som inte minst påverkar bostadssituationen i landet. Bostäderna är
undermåliga i hela landet, särskilt på landsbygden, där den största delen av
befolkningen bor i lerhus.
Rapporten är inriktad på moderna hus och syftar till att hitta hållbara billiga lösningar
som ska kunna användas som alternativ till befintliga konstruktionsmetoder och
utformningslösningar.
Studien baseras på en fältstudie i Mambadistriktet Kilimanjaro i Tanzania under 8
veckor under 2009.
De traditionella lerhusen är mycket dåliga och lever inte upp till en god
levnadsstandard. Levnadsvillkoren är mycket primitiva i dessa hus och utgör en
hälsorisk för de boende. Moderna hus ger en bättre levnadsstandard och är en bra
investering för framtida generationer. Utformning och teknik kan effektiviseras och
förbättras och byggkostnaderna kan minskas genom alternativa byggnadsmetoder.
Byggkostnader kan minskas på flera sätt. Fokus bör ligga på att använda lokala
material för att minimera dyra transportkostnader. Betong är det enskilt dyraste
byggnadsmaterialet och bör i största möjliga mån ersättas med andra material. Det är
dock viktigt att hållbarheten i konstruktionen inte försämras. På lång sikt lönar det sig
att investera i hållbara konstruktioner, även om byggkostnaderna blir högre.
Denna studie har resulterat i flera hållbara lågkostnadsalternativ, till den nuvarande
byggnadstekniken, som lokala husbyggare med fördel kan använda i byggnationer.
Traditionen är stark i Tanzania och förändringar kan ta lång tid att genomföra, men de
förändringar som föreslås och diskuteras i denna rapport kan ses som en god grund för
att inleda en utveckling av den nuvarande byggnadsutformningen och
byggnadstekniken i Mambadistriktet.
1
Abstract
Abstract
As one of the poorest countries in the world, Tanzania faces various kinds of
problems. The housing situation is poor in the whole country, especially in rural areas
where the main part of the population lives in mud houses.
The report is focused on modern houses and is aimed at finding sustainable low cost
solutions to be used as alternatives for existing techniques.
The report is based on a field study in the Mamba district, Tanzania during 8 weeks in
2009.
The traditional mud houses are poor and do not live up to a decent standard of living.
The living conditions are extremely primitive in these houses and pose a health risk to
the occupants. Modern houses provide a better standard of living and are good
investments for future generations. The building design and technology can be
rationalised and improved and building costs can be reduced through alternative
methods.
There are several ways in which building costs can be reduced. Focus should be on
using local materials to minimise expensive transport costs. Cement is the single most
expensive building material and should be replaced by other materials where possible.
However, it is important that sustainability of the construction is not impaired. In the
long term, it is better to invest in proper sustainable building structures even if the
costs will increase.
This study has resulted in sustainable low cost alternatives to the current building
technology that the local builders can benefit from. Tradition is strong in Tanzania
and changes may take long to implement. The alterations suggested and discussed in
this report can be considered as a good basis for development of the current building
design and technology in the Mamba district.
Key Words
Building Design, Building Material, Building Technology, Low Cost Solutions, The
Mamba district, Modern Housing, Sustainable Solutions, Tanzania, Traditional
Housing.
2
Table of Contents
Table of Contents
1 Introduction ............................................................................ 5
1.1 BACKGROUND ........................................................................................................................ 5
1.2 AIM OF THE REPORT ............................................................................................................... 5
1.3 LIMITATIONS .......................................................................................................................... 6
1.4 OUTLINE ................................................................................................................................ 6
1.5 METHODS ............................................................................................................................... 6
1.5.1 Observations and Interviews ............................................................................................ 6
1.5.2 Literature and Other Sources of Information ................................................................... 7
2 An Overview of Tanzania ...................................................... 8
2.1 GEOGRAPHY AND CLIMATE.................................................................................................... 8
2.2 PEOPLE AND SOCIAL CONDITIONS .......................................................................................... 9
2.3 POLITICS AND ECONOMICS ..................................................................................................... 9
3 Mamba District and the Chagga People .......................... 11
4 Today's Architecture and Technology............................... 12
4.1 HOUSING SITUATION IN TANZANIA ...................................................................................... 12
4.1.1 Urban and Rural Areas .................................................................................................. 12
4.1.2 Geographical Variations ................................................................................................ 13
4.1.3 Legislation ...................................................................................................................... 13
4.1.4 Building Institutions........................................................................................................ 13
4.2 TRADITIONAL MUD HOUSES IN THE MAMBA DISTRICT........................................................ 14
4.2.1 Introduction .................................................................................................................... 14
4.2.2 The Beehive Formed House............................................................................................ 14
4.2.3 Mud Houses of Today ..................................................................................................... 15
4.2.4 A Poor Way of Living ..................................................................................................... 16
4.3 MODERN HOUSES IN THE MAMBA DISTRICT ........................................................................ 17
4.3.1 Introduction .................................................................................................................... 17
4.3.2 Settlements ...................................................................................................................... 17
4.3.3 Comparison to Traditional Houses................................................................................. 17
4.3.4 Main Building ................................................................................................................. 18
4.3.5 Additional Buildings ....................................................................................................... 22
4.3.6 Economical Aspects ........................................................................................................ 23
5 Houses for the Future ........................................................... 24
5.1 THE IMPACT OF TRADITIONS ................................................................................................ 24
5.2 ALTERNATIVE BUILDING SOLUTIONS ................................................................................... 24
5.2.1 Plan Arrangements ......................................................................................................... 25
5.2.2 Local Materials............................................................................................................... 25
5.2.3 Foundation...................................................................................................................... 26
5.2.4 Wall Structure................................................................................................................. 27
5.2.5 Mortar and Concrete ...................................................................................................... 27
5.2.6 Roof Construction........................................................................................................... 28
5.2.7 Interior Walls.................................................................................................................. 29
5.3 CALCULATIONS AND DRAWINGS .......................................................................................... 30
6 Conclusion............................................................................ 31
7 Bibliography ......................................................................... 32
8 Index ..................................................................................... 34
3
Table of Contents
9 Appendices .......................................................................... 35
4
Introduction
1 Introduction
1.1 Background
Tanzania is one of the world's poorest countries and the vast majority of the
population lives in great poverty. The country is facing economic problems and not
least it is affecting the housing in the country.
Issues such as poor economic growth, debts and corruption make the country’s
industrial development very slow. Building technology is not evolving significantly
and has been invariant for many years.
In rural areas, people are living in mud houses under primitive conditions. The
primary functions of a building, protection against external elements, are not adequate
in the traditional mud houses. They are in many ways insufficient as residence and
unhealthy to live in.
The economic conditions for people in rural areas means that the prospects of building
modern houses are very limited. Despite this, most people share a dream of building a
modern house of natural stone or stone blocks and get a decent residence. Inexpensive
and sustainable design solutions are required to give as many people as possible a
chance to build a modern house.
The work Reines Rydell, supervisor for this study in Tanzania, is conducting in the
region, forms the basis for this study.
This report is a study of contemporary building techniques of Tanzania in general and
Mamba district in the Kilimanjaro region in particular. Existing building techniques
and the housing situation in Mamba district are analysed and evaluated. The report
describes the surrounding factors that directly or indirectly have an impact on the
building design and construction work. Questions being asked are: How are single-
family houses built in Mamba district? How can modern houses be constructed
cheaper? How can the building technology be more sustainable?
1.2 Aim of the Report
The purpose of the field studies is to increase understanding of a developing country
and its building design and technology.
A detailed presentation of the Tanzania and the Mamba district is made with a view to
improving the overall picture and better understand different processes in society
related to housing.
The report aims to compile and describe traditional and modern housing reflecting on
different aspects of the house types. The main focus is to find sustainable low cost
solutions for modern houses to be used as alternatives for existing building
techniques.
5
Introduction
1.3 Limitations
The report focuses on finding solutions to modern houses exclusively of two main
reasons and the choice has been made to limit the scope of the report;
• Mud houses can be improved to some extent but the standard is considered to
be poor in spite of major enhancements.
• The vast majority seeks to build a modern house and there is a minimal
demand for an improved mud house technology.
The ecological aspect is not considered because of the fact that negative effects on the
environment are minimal in this district. The majority of the population of the Mamba
district has for instance no electricity or vehicles affecting the environment
negatively.
The rationalisations suggested in this report are only a selection of possible ones and
there is room for further studies in the matter.
1.4 Outline
The structure and disposition follows a given layout for theses at C level for School of
Engineering, Jönköping University.
Three main parts form the report; initial part, report part and final part.
The initial part includes two title pages, preface, abstracts in Swedish and English,
key words and table of contents.
The report part is divided into four sub parts. Initially there is an introduction with
background, aim of the report, limitations, outline and methods. The second part is a
theoretical framework with texts about Tanzania and Mamba district and about
housing and building design and technology in the country and in the topical district.
The theoretical part is followed by the result with analysis and proposals regarding
modern houses in Mamba district. A conclusion finalises the report part.
References and appendices constitute the final part of the report.
1.5 Methods
1.5.1 Observations and Interviews
To gain information to this report, a field study has been conducted in Tanzania,
during 8 weeks in February and March 2009. The major part of the report is based on
observations made and interviews performed during the field study. Spontaneous
conversations are part of the observations.
6
Introduction
In order to answer questions posed in this report an empirical study is conducted in
the topical district. Swedish missionaries, Anita and Reines Rydell, have been hosts in
Tanzania. They are living in the Mamba district on the slopes of Kilimanjaro, in a
village called Kokirie. They have many years of experience from social and
construction work in the district.
Reines Rydell has been supervisor on site for this study. He has lived and worked in
Tanzania for almost 25 years and has been involved in various kinds of projects
through the years. Reines has great knowledge and experience in conducting building
projects and is academically trained to a mechanical engineer. His focus is primarily
on missionary work for the Pentecostal Church but a major part of his daily work
involves building projects.
Continuous discussions on the issues related to this study has been carried out with
Reines and he has been answering questions and concerns that emerged while work
was proceeding. This is supplemented by an interview with Reines, carried out in
March 2009, where he shares his own experiences and local and technical knowledge.
The second interview is with Walter Mmbando, gardener and supervisor for Reines
employees. He is born and lives in the village Kokirie in the Mamba district. Walter is
relevant as a source of information thanks to his local knowledge and experience from
building his own house. Walter speaks good English which has made it possible to
conduct the interview without an interpreter. This might otherwise be a source of
errors.
Interviews are conducted on two occasions in March 2009 and can be found in the end
of this report as appendices 1 and 2.
For the information gained on site the applicability is evaluated. It is important to
count with the risk of inaccuracy and partiality.
1.5.2 Literature and Other Sources of Information
A literature review has been made mainly including literature on Tanzania,
Kilimanjaro and the local tribe, Chagga. Literature on the Mamba district is
practically non-existent which means that interviews and discussions are main sources
on this information. Furthermore literature is used for the theoretical framework. A
visit to the Chagga Live Museum has provided additional information on the Chagga
people and local history.
Internet has been an important source on seeking information. Among other sources,
statistical data from the Human Development Report Office (UNDP), UN's global
development network, is used.
7Theoretical Framework
2 An Overview of Tanzania
2.1 Geography and Climate
The United Republic of Tanzania is East Africa’s biggest country with its 943,000 sq
km, which makes the country more than twice as big as Sweden. Tanzania is situated
just south of the equator, bordering eight countries in total. To the east is the Indian
Ocean. [1]
The landscape consists mainly of plateau landscapes, steppes, forests, tropical rain
forests, mountains, lakes and savannas. Along the coasts are tourist beaches and coral
reefs. [2]
Tanzania’s Kilimanjaro is the highest mountain in Africa 5895 meters above sea level,
and one of the country’s most famous attractions. Large mountain ranges such as the
Nguru and Usambara are found in eastern parts of the country. The Great Rift Valley
runs through Tanzania and beyond it is the Crater Highlands. Lake Victoria is part of
Tanzania such as Lake Tanganyika - the world's second deepest lake with a depth of
1400 m. Animal life and vegetation in Tanzania is rich. The tropical rainforests keep
about one-third of the country’s plant and bird range. [2]
The Climate is tropical on the islands outside the mainland and on the coastline. In the
midland the climate is temperate. Due to the varied topography, the weather can
fluctuate unpredictably. The two seasonal winds of the Indian Ocean control rains and
drought. The year has two rainy periods which vary in length depending on location.
During the spring the long rainy season appears and during our summer months, the
country has a long dry period of several months. By the coast the average temperature
is about 30°C but at higher altitudes the temperatures are lower. [1]
Figure 1: Map of Africa Figure 2: Map of Tanzania
8Theoretical Framework
2.2 People and Social Conditions
The population in Tanzania is 37,6 million and the population density is 40 inhabitants
per sq km. Dodoma is the capital but the most populous city is Dar es-Salaam.
Furthermore people are settled primarily around Kilimanjaro, along the coast and by
larger lakes in cities such as Arusha, Iringa and Mwanza. [2]
The standard of living varies greatly in Tanzania. The amount of people living below
the poverty line is today 50%. These people feed on under a dollar per day, which is a
poverty indicator based on consumption or income per person including own
production. [3]
Two-thirds of the population are dependent on agriculture for their survival. These are
often small and unprofitable plantations, at best, sufficient for self-catering. Even
people in cities rent a plot for farming if they have no paid work. [3]
Diseases such as HIV and malaria make the situation even more difficult for people
and it is hard for people to defend themselves against the diseases. In total 6,2% of the
population are infected with the HIV. [4]
There are 130 different tribes in Tanzania and the most famous of these is the Maasai.
Although Tanzania holds such a large amount of ethnic groups there is hardly no
strife between them. Nor is it common with strife between the country's Christians
and Muslims. Christians constitute about 50% of the population and Muslims about
one-third. The old African beliefs still remain, even among many Christians and
Muslims. [1]
The official language is Swahili. English is spoken mainly in commerce and higher
education. In the rural areas, few people speak English. There are numerous local
languages related to the different tribes. [1]
Inequality between men and women is still big but the situation is slowly improving.
Only about 5% of women complete secondary school. If the family can afford to send
children to secondary, priority is mostly given to boys. Women do not have the same
legal rights to inheritance and property as men, and polygamy is still common. [2]
The family and the village community is very important in Tanzania. It is expected to
always support the big family, including relatives, in every way. Those who make
money will be fain to provide money for cost of weddings, doctors’ appointments and
travel, although they may not even afford to feed the immediate family.
2.3 Politics and Economics
After the First World War Great Britain took over Tanganyika from Germany. In
1964 Tanganyika, which was the name of the Tanzanian mainland before the
independence from Great Britain in 1962, and Zanzibar united into United Republic
of Tanzania. The nation developed positively until an economic downturn in the
9Theoretical Framework
1970s. Severe droughts and quick social changes were major reasons to this. In recent
years there has been a positive democratic development with multi-party elections
since 1995. But still today the country suffers from a lot of corruption. [1]
Tanzania is one of the world's poorest nations and for most people life is a struggle to
survive. Tanzania is in the bottom ten percent of the world's economies in terms of
Gross Domestic Product (GDP) which shows the per capita income [5]. According a
report from UNDP [4] referring to 2005, Tanzania has a 156nd place of 177 countries
for an estimated Human Development Index (HDI) value of 0,467. The HDI value
gives a picture of prosperity in the country and take into account both GDP and
welfare parameters such as life expectancy, education and literacy rate [4].
The base of the economy is agriculture. Since a large proportion of the population
depends on agriculture and therefore also of unreliable rains and droughts. [2]
Tanzania is rich in natural resources such as gold, diamonds and natural gas. The
country is dependent on loans and aid from other countries. Tourism is one of the
most important industries and in 2006 the U.S. gave $800 million in revenue. [1] The
country is dependent on loans and aid from other countries. Swedish government
agency SIDA has provided financial support to Tanzania for 45 years. [6]
Tanzania has in recent years made great efforts to reduce poverty and to become less
reliant on international aid. Implemented measures have prevented the inflation and
contributed to economic growth but not to a sufficient degree. [6]
10Theoretical Framework
3 Mamba District and the Chagga People
Volcano Mount Kilimanjaro has two main peaks, Kibo (5 895 m) and Mawenzi
(5 149 m). It is situated in the northern part of Tanzania and borders to Kenya. [7]
The Mamba district, with approximately 8 000 households, is situated on the south-
eastern slopes of Kilimanjaro around 1 500-1 700 meters above sea level. The vast
majority of the Chagga people in the topical district are farmers and live of their own
crops and cattle.
The district is divided into villages and furthermore into plots. A tradition is that a
father’s land is divided between his sons. This way of dividing the land results in a
situation where many families do not have a sufficiently large plot to survive. Many
people have to work for someone else or leave the family and look for work in a city
to be able to provide for the family if they have no education.
The plots consist of arable land, banana plants, trees and houses. The plot boundaries
are not visually seconded with fences or similar but banana plants around the
settlements are providing a private character.
The land is fertile thanks to the consistence of volcanic ash in the soil and the amount
of rain falling in the region. The cool climate on the slopes of Kilimanjaro depends on
the high altitudes and is considered agreeable. The vegetation is dense from different
kinds of plants. The most common trees are eucalyptus, avocado, gravelia and
cypress. The main crops are bananas, maize and beans, which is also the basic foods.
[7]
The people of Mamba belongs
to the Chagga tribe. It is
estimated that the Chagga
people have been living on
Kilimanjaro for 250 to 400
years. The local language is
Chagga but Swahili is the
more common used. In 1848
the Chagga people was divided
into 100 political units, each
with one chief . The chiefs
were often cruel and dominant
and there are many tales
circulating today about this Figure 3: Kibo Peak from Viewpoint in the Mamba District
th
time. Up to the mid 20
century the number of clan leaders was reduced little by little and in 1961 Tanganyika
had its first president. [7] [8]
11Theoretical Framework
4 Today's Architecture and Technology
4.1 Housing situation in Tanzania
Tanzania has a high rate of poverty and the housing conditions are poor throughout
the country. There are major differences in living conditions between rich and poor in
the country. The wealthy part of the Tanzanians lives primarily in Dar es-Salaam. [9]
4.1.1 Urban and Rural Areas
Tanzania is experiencing rapid urban growth. In larger cities such as Dar es-Salaam,
Dodoma and Arusha there are plenty of people who can afford to finance a house or
have access to bank loans. In rural areas, the economical difficulties result in a
situation where the vast majority are living in mud houses or similar still in the 21th
century. [3]
In urban areas most people have a paid work and rent a room or two for the family.
The houses are one storey high and are built in stone blocks. Several houses are set in
a square with a shared inner courtyard for cooking and washing. Usually there is an
electricity and a water supply in connection with the building. The settlements are
often overcrowded and the living conditions unhealthy.
In rural areas most houses
are made from poles and
mud or mud blocks. The
vast majority of the houses
are squared but there are
still circular ones as well.
Some houses are made of
stone or burned bricks, as
illustrated in figure 4,
depending on the location
geographically. Straw
constructions are most
common for roofs.
Figure 4: Bricks in Mwanza, North-eastern Tanzania
12Theoretical Framework
4.1.2 Geographical Variations
There are a multitude of local variations of the houses and the building material use is
determined by local resources. Local traditions also play an important part and affect
the building design and technology.
Large differences in altitudes within the country affect the climate. Various climates
and vegetations means different needs in terms of protection from heat, cold, wind,
rain.
At low altitudes where the weather is extremely hot people are trying to keep the heat
out of the houses and protect themselves against the sun. Mud is used on the roofs for
its cooling effect. Depending on location different building materials are common to
use for building houses. Climate, vegetation and local supply have an impact on the
choice of building materials. In the coastal areas houses are built of coral stones and
the roofs are covered by palm leafs. [10]
At higher altitudes, vegetation is richer providing building timber and shadow on hot
days. The summer months can be quite cold in these areas and the temperature may
reach 10ºC, why the houses are built to let the heat in rather than keeping it out. [10]
4.1.3 Legislation
In urban areas a builder must apply for a permit to build from the governmental
building committee. A permission is not required in rural areas of Tanzania. Common
for both urban and rural areas is that the government owns all land but not buildings,
trees and plants. This can be likened to the Swedish site-leasehold right where the
municipality owns the ground and the property owner only owns the buildings [11].
4.1.4 Building Institutions
Two major building governmental institutions affecting the housing situation in rural
areas in Tanzania are described below.
4.1.4.1 National Construction Council
National Construction Council (NCC) is a government department and one of the
major public authorities regarding construction. NCC is working towards a
development in the local construction industry. Among other things they are
promoting use of local building materials and new technologies. [12]
4.1.4.2 National Housing and Building Research Agency
An institution working under the government towards a better housing situation in
Tanzania is the National Housing and Building Research Agency (NHBRA). They are
focusing on dealing with high building material costs to find affordable solutions with
focus on rural areas. [13]
13Theoretical Framework
4.2 Traditional Mud Houses in the Mamba District
4.2.1 Introduction
The following texts are based on observations and interviews carried out on site.
Through Reines many contacts in the district, there has been an opportunity to
socialise with residents in the Mamba district in their everyday lives. Spontaneous
conversations with people have given insight into how people live and think. Many of
the villagers are either to build houses or have done it earlier, which has been of great
importance for observations in field.
In the interview Reines is sharing his ideas and experiences which is of great
importance for the study. Main contents of the interview can be summarised in four
point:
• Reines background in Tanzania and his present work
• How the building process and the financing of building projects is carried out
• Modern houses compared to traditional mud houses
• The impact of traditions.
The interview with Walter focuses on his experience from building his own house.
The following topics are among others included in the interview:
• His background and present situation
• Traditional mud houses
• Financing of the building
• Construction process
• Plan arrangements
4.2.2 The Beehive Formed House
An old traditional Chagga house is shown in
figure 5. These houses are built in a round
formed as a beehive and they have no windows.
The houses are made of wood and covered with
grass. Poles are dug into the ground and between
those branches are attached on both sides and
constitutes the wall skeleton. Straws are bent
around the branches until a thickness of about 20
centimetres is reached. Traditionally, one half of
the house is used for cattle and cooking and the
other half for sleeping. The cooking is made in
the centre of the house on three stones.
Figure 5: Old Traditional Chagga House
14Theoretical Framework
This mud house construction is no longer built and replaced by another type of mud
house. Though, old Chagga houses can be found throughout the district, today used
for kitchen and livestock keeping.
4.2.3 Mud Houses of Today
In the Mamba
district few people
live in other types
of houses than mud
houses. There is no
production of clay
blocks or bricks.
Compared to the
old Chagga houses
the design of
today’s mud
houses are
different in some
ways. A typical
settlement is
shown in figure 6.
The beehive form Figure 6: Traditional Mud House Settlement of Today
is replaced by a
square or round form with walls and roof separated. Mud is used instead of straws for
the walls and in most houses there are windows. Still in these houses the no floor-
cover is added and people live directly on the natural ground.
Initially poles are dug about 0,3
meters into the ground vertically as
shown in figure 7. Then branches are
attached horizontally between the
poles on both sides. For cheapest
solution wood from the eucalyptus
tree is used. It is the most common
tree in Mamba district and grows in
almost every plot. Eucalyptus is
generally a luxurious alternative in
other parts of Tanzania.
The void between the branches is
filled up with mud or stones. The Figure 7: Mud House Under Construction
walls are plastered with mud on both
sides to make them dense and resistant to weather and wind. The mud is made by soil
from the ground which is dug out on site and mixed with water on the ground.
15Theoretical Framework
Eventually the roof is constructed. The vertical poles differ in height to create a roof
slope. Poles are placed on the slope to hold the roof layer. The poles reach about 60
centimetres outside walls to protect the external walls and to create a covered outdoor
space. In the Mamba district corrugated sheet
metal is most common as roof covering. If the
family cannot afford sheets a plastic cover or
straws are used.
Windows and doors are formed in an early
stage by using poles to form frames. Branches
may be used as a grid as illustrated in figure
8. Boards function as doors and shutters. In
some cases, only a piece of clothing is used
for this purpose. The kitchen consists of three
stones to place the kettle on. Figure 9 shows a Figure 8: Typical Window Construction
typical kitchen.
Some mud houses are reinforced by small rocks
around on the ground around it to prevent pests to
enter the house. Moreover there is no special
foundation construction. The soil is serving as
floor.
The kitchen is positioned either inside the house
next to the sleeping area or in a separate store. The
cattle is almost always put in a separate space.
Outside the house is a latrine, which is constructed
as a deep pit in the ground covered with wooden
boards. The latrine is connected to a large
underground tank which is emptied every 10-20
ee Figure 9: Traditional Kitchen years.
4.2.4 A Poor Way of Living
The traditional way of building is very poor and the
living conditions are extremely primitive in these
houses and pose a serious health risk to the occupants.
Leaking houses and little protection against pests are
two reasons the houses are health hazards.
Most rural houses require significant maintenance and
they only last for about ten years. After this time the
wood is rotten and might be attacked by termites,
depending on which tree is used for the construction.
Figure 10 illustrates a termite infestation in a mud house. Figure 10: Termite Infestation
16Theoretical Framework
The termite is an insect which is very common in tropical areas. They feed on mostly
dead plant material such as trees used in construction [14]. If cypress is used for the
structure termites have made the construction unstable. Young eucalyptus trees are
more prone to rot than heartwood. When the wood is extensively unstable the house
may fall apart.
People living in mud houses are exposed to the climate due to leaks in walls and roof.
This leads to diseases such as pneumonia.
The rain affects mainly the lower parts of the house. The rain bounces to the ground,
removes mud and damages the wood. The mud also naturally dries and falls off with
time. Rats and other pests are common in mud houses and may enter through
loopholes in the walls and other openings.
Further aspects of problems regarding mud houses is related to the smoke from the
open fireplace. The smoke is unpleasant and may cause diseases.
In spite of the negative aspects of mud houses, many elderly do not consider any other
house type than the traditional mud houses. The younger generation are more open to
modern housing solutions.
4.3 Modern Houses in the Mamba District
4.3.1 Introduction
The following texts are based on observations and interviews carried out on site (see
4.2.1 for further details).
4.3.2 Settlements
Modern settlements include a main building and additional buildings on the land
piece. The main building is built of natural stone or stone blocks. Kitchen, livestock
keeping and latrine are held in the separate buildings, and commonly made of wood or
mud.
4.3.3 Comparison to Traditional Houses
Modern houses provide a better shelter than mud houses. Very little maintenance is
needed and the houses last for many generations and up to 100 years if the
construction is made properly. Pests cannot very easily enter the house and people are,
to a greater extent, protected from illnesses related to both pests and the climate. In
summary, it is a very good long term investment, both financially and for health.
17Theoretical Framework
Figure 11: Modern Block House
4.3.4 Main Building
The design of the main building is simple
and the variations are small. The building is
square or rectangular formed and has a
pitched roof. Figure 11 shows a typical
modern houses in the Mamba district.
4.3.4.1 Plan Arrangement
Plan arrangements usually follow a certain
model. It is customary to arrange the rooms
as seen in figure 11 and appendix 3.1 with
separate rooms for girls and boys. This
creates a corridor between the bedrooms,
leading out to the outdoor kitchen, which is
commonly located on that side of the
house. In this way the kitchen is separated
from the porch and the corridor functions as Figure 12: Modern Block House Plan
a short cut through the house.
18Theoretical Framework
4.3.4.2 Foundation
The foundation construction is illustrated figure 13 and appendix 3.3. Natural stone
mixed with mud constitutes the foundation. It is reinforced with larger stones, dug
about 0,5 meters into the ground, by the edges. A thin iron reinforced concrete plate is
cast on top of the enhanced edges and constitutes the base for the masonry. Pipes are
cast in the stone foundation to drain the damp from the soil. The ground around the
buildings are not prepared for water run-off.
The foundation is finished with two layers of concrete to create the floor surface; one
thicker weak mix and one thinner of just cement and water with no sand added.
Figure 13: Modern Block House Foundation
4.3.4.3 Wall Structure
The walls are build on top of the
concrete plate and attached with
cement mortar. Natural stone or
stone blocks are used for the
masonry.
There is two different types of
stone blocks used in the district;
holili and ushira. Both are lava
stones, extracted from large
quarries not far from the Mamba
district.
Holili is the most common type Figure 14: Quarry Near the Mamba District
used in most buildings in the
Mamba district. The name comes from the village Holili, next to the Kenyan border.
19Theoretical Framework
There are large deposits of the block close to the Mamba district. One of them shown
in figure 14 on the previous page. The blocks are being extracted and cut by hand by
villagers.
The holili block is shown in the
building under construction in
figure 15. The block absorbs
heat, which means that a house
built of this stone retains the heat
it is exposed to. These properties
are well suited to the
comparatively cool climate
conditions in Mamba. Especially
during the summer months when
the temperature may go down to
10ºC at night, it is desirable to
have a house of this kind of
stone to be warm at night. Figure 15: Holili Block House Under Construction
Ushira blocks are like the holili blocks a volcano stone and a bit less expensive. It is
extracted from large quarries in the areas Ushira and around Moshi not far from the
Mamba district. In contrast to holili, ushira blocks shut the heat out and give a
relatively chilly indoor climate. The block is therefore suitable where a cool indoor
climate is desirable. It is used only to some extent in the district.
Both block types require transport since they are not extracted in the Mamba district,
which is costly.
Natural stone is a different building material used widely in the district. The
advantages of this stone are many. It's free because it can be extracted directly from
soil most often from the builder’s own site. Most commonly it is used in its natural
form but they can also manually be chopped into blocks. It has the same heat
absorbing properties as the holili block.
Concrete blocks are by far the most expensive building material and are rarely used in
constructions in the Mamba district. It consists of cement, sand and water. The cost of
the material is three times the price of holili or ushira blocks. However, there is no or
small transport costs since the components can all be found in the district. Preferably
they are manufactured on site.
A round-reaching beam of reinforced concrete is constructed above the upper edge of
windows and doors to strengthen the wall construction. It is visible in figure 15 above.
Above this beam two block units in height are added before the roof is constructed.
This is a traditional way to make the house cool.
Some of the modern houses are plastered with cement and painted with oil and water
based colours.
20Theoretical Framework
4.3.4.4 Mortar
Cement is used in mortar in the production of
stone and block walls. The mortar is made of
cement, sand and water and mixed directly on
the ground as shown in figure 16. Among local
builders the mortar is often mixed with a small
amount of cement, 1:8 in order to save costs of
cement and add a large amount of sand. Sand
is collected in Holili (where the holili blocks
are extracted) and cannot be found locally in
the Mamba district. In spite of transport costs –
sand is cheaper to purchase than cement. The
cement mortar is necessary for sustainable
walls and the only satisfactory alternative.
4.3.4.5 Roof
The pitched roof is standard for modern
houses. A typical roof structure is illustrated in Figure 16: Concrete Mixing
figure 17 below and in appendix 3.2. Figure 18 shows a roof structure of poor quality.
Eucalyptus, gravelia and cypress are common woods used for roof trusses and are
found locally in the Mamba district. The structure is simple with rafters and a tie-
beam. Single struts are supporting the framework. Nodes are connected by pieces of
wood and nailed in place (see appendix 3.2 section A – A). Splines are laid on the
wooden roof structure to enable attachment of the corrugated sheet metal. The roof-
ridge is covered by sheet to prevent water leakage through the joint.
Figure 17: Typical Roof Structure Figure 18: Poor Roof Construction
4.3.4.6 Supplementary
Interior walls are constructed of stone in the same manner as the exterior walls. On
the inside, the walls are plastered with cement mortar. This action claims that the
inner surface is made even with a pangas, a large knife, since the blocks vary in size.
21Theoretical Framework
Porches are often constructed of concrete pillars and beams. They are not used for
social intercourse, as we are used to in Sweden, but are important visual expressions.
This means that people strive for a nice design and an ostensibly expensive
construction. Concrete is regarded a luxurious and is used as much as possible to
improve the visual expression of the porch. In spite of the pillars’ load-bearing
functions, a concrete mix of one part cement and 8 parts of sand is used locally.
At the bricklaying of the walls voids for windows and doors are made. Eucalyptus is
usually used as shutters and doors and to frame windows and doors. Window
openings are also provided with a grid for security reasons. A step further, which is
not always a priority, because of additional expenses, is to add mosquito nets and
glass to the windows.
Very few houses have electricity or running water supply and there is no special
arrangement for ventilation. The houses rarely have a system for roof drainage.
4.3.5 Additional Buildings
4.3.5.1 Latrine
A small house on the plot serves as
toilet. The floor is made of
concrete with an opening over a
pit. Connected to the pit is a large
tank, sometimes covering several
latrines, which is emptied every
10-15 years. Some people choose
to build an indoor water toilet, but
most commonly an outdoor latrine
is built. Possibly also a simple shower room. Figure 19 shows a Figure 19:
Combined Toilet and Shower Room toilet and shower room under
construction.
4.3.5.2 Kitchen and Livestock Keeping
When a modern house is built the former
mud house is converted into kitchen and
livestock keeping. In some cases, a kitchen
is built out of stone or bricks. The traditional
three-stone kitchen is used by people living
in modern houses as well. An option used by
some people is a small charcoal stove. The
cattle is kept in the kitchen or in separate
wood houses. The cow in figure 20 is kept in
a combined storage of livestock and kitchen.
Figure 20: Storage of Livestock and Kitchen
22Theoretical Framework
4.3.6 Economical Aspects
The current situation with the financial crisis hits poor countries hardest according to
reports from the World Bank. Rising prices affect poor people most severely and
lowers living standards further. The Tanzanian shilling has weakened against the
dollar, which means a further rise in prices. [15]
The opportunity to build a modern house is, for people in rural areas, very limited. To
have a chance to save money for a house a builder is required to have a paid work
besides agriculture and to have no family to supply. In most cases, the builders are
dependent on external aid, either from a rich relative or from other financial
supporters. Bank loans are not available for someone without capital. People living in
poverty have no access to any bank and insurance services.
Education is a chance to, in the long term, be able to afford a modern house.
However, secondary school, for young people between 15 and 20 years, is very
expensive and many farmers cannot afford to put their children in school at this level.
Since people living in poverty have less access to education and thus knowledge than
rich people, their ability to build good houses is further limited.
A normal sized modern house costs about SEK 20 000, including costs of materials
and labour, but also requires that the builder does most of the work, except
bricklaying, himself. This can be contrasted to a carpenter’s monthly salary of about
SEK 500 per month. In practice, money is spent on the cost of living since people are
already struggling to survive on their salaries.
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5 Houses for the Future
5.1 The Impact of Traditions
The tradition is very strong in Tanzania and has a central role in people's lives. It
shows in builders’ ways of planning houses as it has the effect that the houses are
built according to a standard solution with relatively small variations. Awareness of
the importance of traditions makes it easier to understand why Tanzanians build in a
certain way.
In poor areas, like the Mamba district, access to information is limited due to the lack
of access to television and newspapers. People are travelling very little and get very
few influences from outside their region. These aspects make the construction
progress very slow. Construction solutions and ideas considered reasonable for us can
be both incomprehensible and uninteresting for builders in the Mamba district. It is
important to be clear on this issue when discussing development ideas. It may actually
be a long process to implement a change.
Problems for local builders occur when the technical solutions that are good in the
long run cost more than a more short-term solution. People struggling to get food for
the day are planning out of a short term perspective, why the long-term way of
thinking can be difficult to identify with.
5.2 Alternative Building Solutions
An active and balanced choice of building design and technology can hold down costs
and improve life – the two parameters that are most important when building in the
Mamba district. There are several ways in which building costs can be reduced.
However, it is important that sustainability is not impaired. In the long term, it is
better to invest in proper sustainable building structures even if the costs will increase.
Since cement is the most expensive building component focus should be on replacing
cement with other material where possible and on finding solutions where cement is
used as little as possible.
24Results
5.2.1 Plan Arrangements
By reducing the number of walls in a
house space is optimised and material
costs are saved. Appendices 4.1.1 and
4.1.2 demonstrate an alternative plan
arrangement for a modern house, where
unused spaces are reduced to a minimum.
Figure 21 demonstrates the smaller of the
two suggested plans, adapted to a family
with two children. The illustrated plans
shown in the appendices are for families
with four and six members and suitable
for average families in the Mamba
district. The living area is reduced to save
on costs for building materials but are
spacious enough for the intended number Figure 21: Plan Suggestion
of residents. The kitchen is positioned
where the distance between the house and the kitchen is reasonable and not in direct
connection to the porch.
5.2.2 Local Materials
An effective way to save on construction costs is to use as much local materials as
possible, as transportation costs will thereby be minimised. Corrugated sheet metal,
reinforcement iron and wood can also be purchased locally in the district. Sand and
blocks are components which cannot be found locally.
Since natural stone , shown in figure 22,
is free or very cheap to get hold of in
the district, it is desirable to make
maximum use of this in constructions.
However, it is common to use holili
blocks since this is considered better-
quality and easier to manage for the
mason. The cost of holili blocks
amounts to approximately SEK 5000
which is about one-fourth to one-fifth
of the total building cost.
Transportation costs are included to the Figure 22: Natural Stone
estimated cost. Natural stone has as
good heat absorbing properties as holili blocks but represents a significant cost
reduction, since they do not involve any transport or purchase costs. Natural stone is
25Results
therefore preferable in terms of costs and is comparable holili blocks in terms of
durability and heat absorbing properties.
5.2.3 Foundation
The foundation can be improved to make it more sustainable and to make the water
drainage more efficient. The changes suggested below will mean slightly higher costs
but will pay off in the long term because of its sustainability. Concrete is rarely used
among local builders for this purpose but is a good alternative to the existing mix with
natural stone and mud. Figure 23 and appendix 4.3 show an alternative foundation
solution. Reinforced concrete is dug into the ground and is a mixture of with cement
(1 part), sand (3 parts) and course macadam or lava dust (4 parts). Macadam can be
purchased locally and is relatively cheap. The lava dust is the stone which is cut away
at the chopping when making holili or ushira blocks. It can be purchased very cheaply
or for free since it is a decay product and it has very good additive properties.
The ground is used as form when casting the concrete base. After finishing the
concrete a part of the ground is dug out and filled with macadam for drainage
purpose. On the ground level chopped natural stones, ushira or holili blocks are laid
and attached with cement mortar. This creates a stable foundation. On top of this there
is a concrete plate reinforced with iron bars and a damp-proof coarse. This is a good
stable and damp proof base for bricklaying. Inside the edges the space can be filled up
with soil and finished with a layer of gravels. On top of this is a reinforced concrete
layer, which constitutes the floor.
The mortar mix is very important as mentioned below (see 5.2.5.1), and the strength
of the construction relies on a high-quality mortar mix.
Figure 23: Proposed Foundation Design
26Results
5.2.4 Wall Structure
The masonry is positioned on the concrete plate a bit
outside the foundation, as shown in figure 24 to the
right. This is to prevent the water run-off to affect the
foundation negatively (see appendix 4.3). This can be
compared to the existing technique to place the
masonry in the centre of the concrete plate (see
appendix 3.3).
The round-reaching beam made of reinforced concrete
is an elementary part of the walling system to hold the
walls together. An alternative way of making this Figure 24: Foundation Detail
beam is to use concrete where the macadam is
replaced by lava dust. This is a good way to supplement the traditional concrete mix
but to keep the strength of the product at the same time.
The existing technique to add two units of blocks in height above the concrete beam is
not necessary in the climate of the Mamba district. It is a traditional way of making
the house cool and a good way of building where the climate is hot, but not in the
topical district where the climate is rather cool. By constructing the roof directly on
the concrete beam the roof is lowered from a height of about 2,70 metres to about
2,40 metres and the indoor climate becomes more desirable. This is also a way to save
on building costs since less blocks and cement mortar is used.
5.2.5 Mortar and Concrete
5.2.5.1 Mortar
It is important to mix a mortar with the right proportions of sand and cement. A
common way among local builders, to save on the costs of cement, is to use a large
part of the sand and only a small amount of cement. This results in a short-lived
construction that leads to high costs for maintenance. The typical mix of mortar with
one part cement and eight parts of sand is not sufficient for a sustainable construction.
A mortar mix of one part of cement and three to four parts of sand is better be used.
With this mix the walls are more sustainable and need little or no maintenance.
27Results
5.2.5.2 Floor
The existing way of constructing a concrete
floor is poor, deteriorates fast and cracks may
occur. This is visible in figure 25. When
adding the thin layer of only cement and
water (see appendix 3.3) it has often been
some time and the under-lying layer is
already deteriorated. It is of great importance
the floor is strong because of the wear it is
subjected to. A more sustainable solution is
to cast a layer of strong concrete directly on Figure 25: Deteriorated Concrete Floor
the gravel layer (see appendix 4.3).
5.2.5.3 Porch
As mentioned earlier, porches are, for the
villagers, an important part of the house
and the design is prioritised. To make the
construction durable and safe the weak
concrete mix of 1:8 with cement and sand
should be replaced by a strong mix of 1
part of cement and 3 parts of macadam or
lava dust. The horizontal concrete beams
on top of the pillars and below the roof
structure can be replaced by timber to save
on costs. However, the visual expression
might be considered degraded by this last
mentioned measure. A typical concrete Figure 26: Concrete Porch
can be seen to the right in figure 26.
5.2.6 Roof Construction
In the typical construction used in the district almost all the roof load is led to the
centre of the horizontal tie-beam, stressing the beam and impairing the strength.
Sustainability can be improved significantly by making small changes in the structure.
Figure 27, on the next page, and appendix 4.2 illustrate how this alternative can look
like and is a typical Swedish solution where load is transferred towards the wall
structure.
For greater strength the nodes should be connected by two parallel pieces of wood and
by double struts; one on each side of the beam and rafters (see appendix 4.2 section A
– A). This can be compared to the solution in appendix 3.2 section A – A where single
struts are used. The amount of wood used is equal in both solutions but by using two
28Results
parallel struts instead of one single the strength of the structure is significantly
improved.
It is important to cover the roof-ridge properly to avoid leakage. By covering the ridge
with a overlapping sheet, damages are prevented.
A water run-off system connected to the roof base is a good way to protect the wall
from rain and can be constructed of sheet metal. Considering the reduced water
impact of the wall, additional costs are negligible.
Figure 27: Proposed Roof Structure
5.2.7 Interior Walls
Today the interior walls are constructed of stone like the external walls. Using a local
wood, or making a simple mud wall will save costs of cement, sand, blocks and
labour. Simpler interior walls of mud can be treated with cement plaster to improve
the aesthetics. This is a satisfactory alternative, as the interior walls of blocks do not
fulfil any useful function. Existing interior walls made of blocks have no thermal or
other significant functions. If the house is bigger, a load-bearing wall of blocks may
be necessary.
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