< 3rd IDA Education Project: Prototype Rural Primary Schools

Background

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By the mid-1980s, Sierra Leone’s economy was in freefall and we had very little work in the office.  I had been working on rural primary school project for the World Bank developing prototype classroom buildings to be built by small contractors and designing a new teacher training college to be constructed outside of Freetown but when this work was finished there was little for me to do. 

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In October 1985 I was however offered a position in the World Bank Project Implementation Unit as a local consultant (paid for by the World Bank) to research various aspects of primary school design and construction.

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The overall objective of the consultancy was to prepare designs for classroom buildings that could be built at minimum cost by rural communities using as far as possible local materials and building methods and my brief was to: compile an inventory of traditional building materials and techniques and develop ways of improving them; establish guidelines for the design of primary school classrooms and furniture; construct and evaluate prototype primary school buildings and furniture; plan for the in-service training of local people associated with school construction and liaise with local architects and others associated with primary school construction.

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Building Materials

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The building materials most commonly in use in the rural areas at the time were mud blocks, sand-crete blocks (usually of very poor quality), ‘wattle and daub’, bush sticks, thatch and of course ‘corrugated iron’ (or more accurately, profiled steel) roof sheets.  There was a complete lack of two basic buildings materials: clay suitable for making fired bricks and lime.  This meant that lime and cement (or the clinker to make cement) had to be imported and were thus expensive, especially in the rural areas. 

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My first task therefore was to develop materials or building techniques that could be used to replace cement and lime or reduce the amounts required for simple, rural buildings.

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I investigated the possible production and use of rice-husk ash cement (the staple food in Sierra Leone is rice which is grown in large quantities) as a replacement for Portland cement.  I experimented with the use of traditional mud blocks and stabilised-soil blocks (using both the ‘Cinva Ram machine that had been developed by Peace Corps and a new block-making machine, the ‘Brepac’ machine that had been developed by the UK Building Research Establishment) for constructing walls.  I also experimented with various foundation types for all wall types ranging from traditional concrete footings to rammed stone footings with concrete block foundation walls. 

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Thatched roofs had largely disappeared and had been replaced for most rural buildings with profiled steel roof sheets which are noisy when it rains and transmit heat when the sun shines.  I experimented therefore with fibre-concrete roof tiles made on machines made then by Parry Associates in UK.  The tiles were fairly simple to produce but there were problems in manufacture and use: the mixture used for making them had to be very carefully controlled and they had to be properly cured; they were much heavier than profiled steel sheets especially when they were wet which meant that the roof structure had to be stronger and thus more expensive.  Alignment and fixing were also difficult when bush-sticks (the cheapest and most available material) were used for the roof structure. 

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The Parry roof tile machine could also be used for making fibre-cement floor tiles and these were more successful than the roof tiles in that a hard-wearing and durable floor finish could be provided without having to source large aggregate which is always difficult and expensive in the rural areas. 

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The Parry machines are still being made and used in Africa and other parts of the developing world.  The manufacturer is now Parry Building Products in UK and can be contacted at www.parrybuildpro.com.  They also manufacture other machines such as block and brick making machines and hand-tools.  Unfortunately the Brepac machine (which was made by MultiBloc in UK) is no longer in production.

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Primary School Classroom and Furniture Design

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My other main task was to develop designs for buildings and furniture that could be easily constructed using locally available materials and building techniques.

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Furniture Design

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The design of the prototype classroom buildings was dependent on the size and layout of a standard classroom which itself is dependent on both the design and size of the furniture and on the materials used for construction of the building.

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The first thing that I did therefore was to carry out an anthropometric survey of a number of primary school age pupils and the size of the furniture was based on this survey.  I reviewed the types of classroom furniture that were in use at the time and experimented with designs for furniture that were based upon a design developed by UNESCO in the 1970s which could be made from local timber.  The furniture consisted of a desk for two pupils with two freestanding chairs.  The furniture was designed to be strong, simple to make and maintain by local carpenters using locally available timber with no complicated joints.

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Classroom Design and Construction

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I developed a design for a standard classroom that could accommodate 44 pupils using double desks and single chairs.  They were designed in such a way that they could be built using sun-dried mud bricks, stabilised-soil blocks or sandcrete blocks according to the budget of those constructing them.  The classroom walls on both sides were stabilised with block piers (of whatever material was being used for the walls) at approximately 7’ 6” (2.25 metres) centre intervals and these also supported the roof trusses (see below).  Where there were front access verandas the rafters were supported on large blockwork columns.  The buildings had no concrete columns or beams or reinforced concrete of any sort and in fact the only concrete used was mass concrete in the foundations (in the cases where stone was not used); in the floor slabs; in pads on top of the blockwork piers and columns to support the roof trusses and in pockets in the cross- and end-walls to retain the holding-down bars for the trusses. 

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The classrooms could be assembled in a number of ways: as a two- or three-classroom building with an office and store at one end and with access from a front veranda or as a two-classroom building with access to the two classrooms from a central space that could also be used a subsidiary teaching space with an office and store at the rear.

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The classrooms were lit either by timber-framed openings with timber shutters or by perforated brick or block panels in the walls, set between the blockwork piers.  The section of wall above the shutters was supported either by the top member of the shutters or by a relieving arch formed in the blockwork (the latter only in the walls made from stabilised-soil blocks). All doors and shutters were ledged and braced and all of the timber for shutters and doors was sourced locally in each village.

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The shutter windows were protected from the sun and the mud block or stabilised-soil block walls were protected from the rain by large roof overhangs, which are essential in a country like Sierra Leone that has large amounts of rain and a hot and humid climate.

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It quickly became obvious that the real design problem was, as in the school project in Zambia, how to construct the roof; the same problem but here demanding a very different solution.  Most local carpenters in West Africa can build a good roof for a house because the roof span does not usually exceed 3 or 4 metres.  The width of a primary school classroom is however at least 6 metres (and these days more like 7 metres) and the length is around 8 or 9 metres and this makes the construction of a good roof technically quite difficult.

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My solution was to use timber trusses at approximately 7’ 6” (2.25 metres) centres supporting timber purlins at about 3’ 0” (90 centimetres) centres supporting either profiled steel sheets or fibre-cement roof tiles.  The trusses were not however made from milled timber but from ‘bush-sticks’ cut from the local bush.  These bush-sticks are a product of the ‘slash and burn’ agriculture traditionally practiced in Sierra Leone.  The bush is cut down to ground level and piled up to dry on the land that is to be cultivated.  When dry it is burned and the ash dug into the ground before crops such as hill-rice are planted.  The land is used for agriculture for four or five years and then left fallow for a period of up to 12/15 years (with a growing population this fallow period has however been getting shorter and shorter).  During this fallow period one of the most prolific plants that grows is called in Sierra Leone, ‘monkey apple’ and this large shrub produces long, straight and very strong stems which have traditionally been used for scaffolding.  They grow to lengths of up to 6 or 7 metres with a diameter of up to 15 centimetres.  This, and the fact that they are much cheaper than milled timber made them ideal for use in the roof trusses that I designed for the schools.  I experimented with various types of roof truss before coming up with a scissor-truss which seemed to be the most simple and efficient solution (see roof truss drawings).

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Prototype Primary School Buildings

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I had little or no funding for the construction of prototypes and had therefore to find individuals or agencies that wanted to construct school buildings (and also had some funding) and required some technical assistance.  During the course of the assignment I therefore worked with a number of individuals, agencies and communities and these included a VSO (UK volunteer), several Peace Corps (US volunteers), a Catholic priest, a German government funded rural development project, an international NGO and a community activist who wanted to construct a primary school in his village and all together twelve prototype classroom buildings were constructed.

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Lessons Learned & Conclusions

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A number of lessons were learned with regard to materials and construction that still have some relevance today.  The use of stabilised-soil blocks proved to be a very effective way of improving the quality of walls while not substantially increasing costs.  The BREPAC machine (which has unfortunately gone out of production) produced very high quality blocks although there were some issues encountered with its use which will be gone into in a later post.  Even the cinva-ram machine, if properly used can produce very good blocks but these blocks must have some protection from heavy rain such as large roof overhangs or rendering and must be used with stone or concrete foundations.  It was concluded that, if good quality foundations are provided and the external walls are protected from the rain, both mud and stabilised-soil blocks provide economic and acceptable materials for walls.

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The use of the fibre-cement roof tiles proved to be more problematic.  Although fairly simple to make some problems were encountered in their manufacture and use.  The mixture used for making them has to be carefully controlled; they have to be properly cured and they are much heavier than profiled steel sheets especially when wet and therefore the roof structure has to be much stronger.  Alignment and fixing of the tiles also proved to be quite difficult particularly when used with bush-pole trusses and purlins and it was concluded therefore that profiled steel sheets are still probably the best roofing material for the rural areas.

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The sand-cement floor tiles produced on the Parry Associates machine were more successful.  They produced a hard-wearing floor surface which would stand up to timber furniture and did not require, unlike mass-concrete floors, any large aggregate which is always difficult to find and transport and is expensive.  They were laid on 50 mm of screed on a consolidated laterite bed without a concrete slab and proved to be very effective and fairly simple to lay.

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I investigated the production of rice-husk ash but concluded that because of transport, machinery and packaging costs, it was not economic and that it was better to concentrate on reducing the amount of cement required in construction.

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A further lesson concerned the involvement of communities in the construction process.  The most successful projects were those that originated in the community and where there were local people involved in the supervision of the construction.  Where the idea for the construction of a classroom building had originated outside the community, it proved to be much more difficult to get the community involved and to complete the building. 

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A degree of technical supervision was also necessary for success especially with regard to the roof construction and the more such supervision there was, the better the quality of the buildings and the faster that they were completed.  However, no matter how much community involvement and technical supervision there was, there was very little chance of success if the community had to bear the greater part of the cost themselves.  This was because, even then, building materials and to a degree skilled labour were so expensive that small rural farming and fishing communities just could not afford to construct a primary school building using improved materials.

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By the end of the consultancy I had developed simple designs for primary school classrooms buildings and furniture together with designs for rural teachers’ houses and VIP-latrines that could be used by individuals or agencies interested in constructing rural primary schools using mainly local materials and available skills.

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The drawings that are attached show the development of the designs for the buildings and furniture and the photos shows some of the buildings under construction. 

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The final report that I produced at the end of the assignment, ‘Primary School Construction in Sierra Leone’ covers: the background to primary education in Sierra Leone; improving access to primary education; the design of primary school facilities; building materials and a guide to construction.  It also shows the final designs for buildings and furniture which were used in a UNCDF-funded project that I managed that constructed ten primary schools around Bo Town in the east of the country and this project is covered elsewhere on the web-site. 

Although the designs and construction methods were developed quite a long time ago now, I feel that they could still have some relevance today, albeit with some modifications, as the problem of providing sufficient numbers of primary school classrooms in rural, sub-Saharan Africa does not seem to have gone away.