Local Materials
Kenya has a very rich history, with late colonialism by Europeans, particularly the British, having had a great influence on materials, construction methods and building code/regulations. There are many examples of vernacular architecture to be found in the homesteads of the various tribes, who made full use of local materials. Adobe bricks and coral stone do exceptionally well on climate compared to other materials. Mabati scores very poorly on climate and must be imported. The relationship between manufacturability and price is important if you have a low income, because then you want to do as much as possible yourself to save costs. It is striking that the natural materials cost the least and are also the easiest to process. As soon as you start looking at industrialized materials, the costs are higher and in general you need more skills to build with them. Adobe bricks and Coral stone stand out, they are a processed, relatively industrial, product but very cheap and easy to build with. What is striking is that a lot of materials are available locally. Rammed earth is not as good, because of the difficulty of obtaining suitable soil. It is also noticeable that in general most industrial materials that are available locally, are expensive, except for mabati, which is very cheap. It is also striking that all natural products require a lot of maintenance, which may make them more expensive in the long run. Adobe bricks and coral stone however are made of natural materials and require little maintenance. Local materials are also generally cheaper than imported materials. Local materials are much more sustainable then imported materials.
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"Which of the locally availabale materials are best suited for the use in future building projects in Bomani?"
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LOCAL?
To get an answer to the research question, we first defined the concept of the word ‘local’. We have divided this into three different parts; the availability of the raw materials, the availability of the imported sources and the travel time.
Locally available raw materials grow or are extracted from nature or from quarries in the immediate vicinity of Bomani.
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By the availability of the imported sources, we looked at the materials that are available locally, but are not produced locally.
The maps show the travel times when walking and with a vehicle within a radius of 50 km.
HISTORICAL TIMELINE OF ARCHITECTURE IN KENYA
To get a better sense of the context and the materials, we researched the history of Kenya.
Kenya has a very rich history, with Arabic / Portuguese influences and with late colonialism by Europeans. The different cultures have had a great influence on materials, construction methods and building code/regulations.
In history there has been a balance where people lived in harmony with nature and materials. With the colonization of Europeans, this was lost. It created large exports from Kenya to these countries. In contrast, many materials have been -and are- also imported.
DIFFERENT TRIBES IN KENYA
To find out what it takes to make homes entirely of natural materials, we looked at the different tribes along the coast of Kenya: the Bantus, the Nilotes and the Kushites.
The Bantus often use walls of mud in with a frame of crumb wood, which they optionally provide with planks. They cover the roofs with grass, which they have to provide with a new layer every rainy season.
The Nilotes make a frame from wooden branches, after which they smear them with mud, cow, urine and grass.
The Kushites also make a frame from wooden branches, which they then cover with woven grass mats.
CURRENT SITUATION IN KILIFI, KENYA
To get a better sense of the context and the materials, we researched the history of Kenya.
Kenya has a very rich history, with Arabic / Portuguese influences and with late colonialism by Europeans. The different cultures have had a great influence on materials, construction methods and building code/regulations.
In history there has been a balance where people lived in harmony with nature and materials. With the colonization of Europeans, this was lost. It created large exports from Kenya to these countries. In contrast, many materials have been -and are- also imported.
THE RAW MATERIALS
From the analysis, we have determined 19 different raw materials that can be found around Bomani. A difference has been made in what can be obtained locally and which materials have been imported. The use of local raw materials has many advantages in terms of price, labor transport, autonomy and climate. By consciously applying these in the building materials, less has to be imported, making the area less dependent on other countries.
MATERIALS AND PRODUCTS
When we determined all the raw materials, we created a bubble diagram. The diagram shows an overview on which end products can be made, from the raw materials. This shows (in red) which materials have been imported or extracted in an unnatural way. In the green are the materials that have been extracted in a natural way and are available locally.
MATERIALS AND PRODUCTS
Based on the different raw materials, we have 18 different end products that are made from both imported and local raw materials. The end products that can be made locally are mainly found in the way different tribes build, such as: mud and branch walls, wattle & daub, turf and covered grass roofs.
The use of steel roofing sheets started to rise after independence, because the material is seen as a sign of independence and modernity. The material itself has few good properties; it creates an unpleasant indoor climate and is imported from China.
COMPARISON MATERIALS
COMPARISON RAW MATERIALS
To get a good overview of the different raw materials, we have provided it with a rating. This we did on the basis of 4 different criteria: sustainability, price, manufacturability and availability.
Noticeable is that mainly all-natural products that can be found around Bomani score best, such as: grass and even cowdung.
COMPARISON CONSTRUCTION MATERIALS
In addition to rating the raw materials, we also rated end products, which we did on the basis of 6 different criteria: sustainability, price, constructability, maintenance, availability in the proximity and local climate.
Noticeable is that mainly all-natural products score best, such as: adobe bricks, cob and coral stone.
LOCALLY SOURCED VS IMPORTED & CLIMATE
An important aspect of a material is its relation between locality and its capability to deal with the local climate. It can be noted that most locally sourced materials work well with the local climate. Most techniques used by local tribes, such as mud walls, work very well and are vernacular examples. Another notable extreme is mabati. It has to be imported and does not work well with the local climate, which in that sense makes it an unviable material. One of the best performing materials is adobe bricks. It is perfect for the local climate and can be locally sourced or made.
PRICE AND MAINTENANCE
The relation between price and maintenance is a very important one. In any case it is preferable to use materials that require little maintenance, as it saves time and money. It can be seen that most natural materials are cheap, but they require a lot of mainenance and cost after construction. It can also be noted that most industrialised materials, such as concrete, mabati, clay bricks and glass require little maintenance, but they are also more expensive. On exeption on this is adobe. Adobe is a natural material that requires little to no maintenance, but it also is very cheam. This also counts for coral stone
AVAILABILITY IN THE PROXIMITY & PRICE
The relation between the availability and price, is an important relation, as if a material is not available in the proximity, a lot of transport cost is needed, making those materials less viable. This is different form being locally sourced or imported, as imported materials can also be available in the proximity. It can be noted that most natural materials have a hight availability in the proximity, and are low priced. More industrialised materials are also available, but have a higher price point. A very notable extreme is rammed earth. Because it needs cement, and a certain type of soil, it is relatively expensive and not readily available, making it not a viable option.
MANUFACTURABILITY & PRICE
This comparison is made, because people in the area have a low income, it is important that they can process the materials themselves to save money. It can be noted that natural materials in generally require little skill and specialised tools to be made. They also are often the cheapest. In the graph it is also notable that the more industrialized materials, such as coral stone, concrete, clay bricks and glass generally require a lot more skill and specialised tools in order to be made and used successfully, which makes them a lot less viable. Another notable material is adobe bricks. Adobe bricks are relatively refined as a product, but still has a very low cost and is easy to use.
LOCALLY SOURCED VS SUSTAINABILITY
This graph shows the ralation between sustainability and the locality of materials. It is striking that almost every local material is sustainable and all imported and more industrialised materials are worse. What’s also notable is the fact that materials like, compressed earth bricks and rammed earth are less sustainable because they have cement integrated. One extreme is coral stone. Even though it is a natural material, it is a fossil, so it is a finite resource, making it not that sustainable
BEST MATERIALS FOR BOMANI
Looking at the overall score it can be concluded that a few materials are really suitable for construction in Bomani, having the best overall score. For walls two materials seem to be really good: Adobe bricks and Coral stone. For roofing, thatch seems to be a good choice.