Sierra Leone 7: The Upgrading of Bo Teacher’s College Project/3

3-classroom unit under construction.

Construction Details

The buildings were designed to be constructed simply and economically; to deal with the hot and humid climate and to use as far as possible locally available materials.

In most rural communities in the country there are masons and carpenters capable of constructing simple buildings using mud blocks, bush-sticks and CI sheets and it was decided at the start of the project to use these or similar materials, making improvements where possible.

The use of mud blocks was unacceptable to Government and therefore the buildings were constructed of soil-cement blocks (using a ratio of 10% cement to 90% soil on most sites) made in BREPAC machines imported by the PEU.  The machine that I had used when I was building the prototype schools had worked very well but the management of the company that made them had changed and the quality of the new machines was not very good and there were therefore constant problems during the block-making process.

Blocks being manufactured using the BREPAC machine

The blocks produced by the machines however were generally very good quality and were used un-rendered wherever possible.  Gable end walls which were exposed to the rain were rendered as were columns and piers on both sides of the buildings and walls along the verandas.  The masons had no problems with laying the blocks.  It should be noted however that, as long as adequate footings and foundation walls are provided, it would be perfectly feasible to construct similar classrooms using un-stabilised mud blocks.

Footings were constructed of either concrete using sand and large aggregate gathered from nearby rivers or of large stones set in mortar.  Foundation walls, to a minimum height of one foot above ground level were constructed of sand-cement blocks made on site in wooden moulds.

Footings being constructed of large stones set in mortar

Mass concrete footings; foundation block-work being set out.

Floors to all rooms and the access verandas were constructed of three inch (75mm) unreinforced mass concrete laid in bays with movement joints on well-compacted laterite fill and self-finished with a steel trowel (there were no screeds).  No reinforced concrete was used in the construction of the buildings.

Typical section through the access vearanda

Typical section through the rear wall

The roofs were constructed of CI sheets on bush-pole purlins on bush-pole trusses to the same design as that I had used before for the Third Education Project.  We had a sample truss tested by the Engineering Department of Fourah Bay College and it proved to be extremely strong and more than capable of resisting the fairly low forces that would be exerted on it when in use.  The trusses were secured by reinforcing rods built into the walls and columns.  Bush poles are fairly termite resistant but as added protection we treated them with used vehicle engine oil which is a very cheap, effective and fairly innocuous treatment against termite attack.  The only modification to the usual method of fixing CI roof sheets was to blind-rivet the ridge pieces to the top sheets rather than nailing them into the purlins which overcame, very simply, the main cause of leaking roofs.  Ceilings were provided usually locally-woven grass mats which provided a source of income to the villagers.

Bush-pole truss being tested at Fourah Bay College Engineering Department

Bush-pole trusses under construction; the central pole was cut short under the truss once the trusses were fixed.

Typical classroom interior with trusses exposed.  Where local mats could be found they were fixed under the purlins as a ceiling.

Doors, window shutters and their frames were made centrally by a team of carpenters at BTC out of hardwood purchased from local suppliers.  Much of the timber was pit-sawn in the surrounding forest and we had to provide the loggers with the necessary seven foot (2.1 metre) saws.  The doors and shutters were delivered to site complete with their frames and were built into the walls as they went up using wire nail hold-fasts for fixings.  All frames had an extended double frame at the top which acted as a lintel and avoided the need for any reinforced concrete lintels.  All of the doors and shutters were treated with used vehicle engine oil to protect them against termites.

A log being hand-cut into boards to be used for making doors and shutters.

A typical shutter with a double-frame at the top acting as a lintel.

2-classroom unit under construction.

Veranda columns before plastering showing fixing of trusses.

A well being excavated.

A typical veranda after plastering.

Gable end wall with roof under construction.

VIP-latrines under construction.

Sierra Leone 6: The Upgrading of Bo Teachers’ College Project/2

Implementation of the primary school component of the project

My contract with the World Bank ended in May 1988 and in June of that year I was appointed (not without some difficulties) as Chief Technical Advisor to the Upgrading of Bo Teacher’s College Project.  A project execution unit (PEU) was set up at Bo Teacher’s College (BTC) which was to be headed by a national architect.  Unfortunately this architect was not appointed for another year and a half and so I was de facto head of the PEU until he was appointed and, as he did not have that much experience, remained even after this the day-to-day manager of the project.

The PEU was staffed with two United Nations Volunteers (UNVs) both civil engineers, four senior site supervisors, eight site supervisors and four wells technicians.  All supervisory staff apart from the UNVs were locally recruited and all were given a great deal of training both on-the-job and at specially designed workshops.  I must state here that the successful implementation of the project would have been impossible without the hard work of both UNVs and I am particularly indebted to Ravi Raveendran for his support throughout the project.

The ten pilot primary schools that were selected had existing buildings but these were inadequate for their purpose: the buildings were generally in a poor state of repair; the classrooms were small and under-lit; classroom furniture, if it existed, was in a bad state of repair; toilet facilities were poor or non-existent; water supplies were dirty or non-existent; and access to the schools was difficult due to the poor state of the roads particularly in the rainy season.

As stated in the previous post very little had been done in the way of community development in the pilot villages or of informing the villagers of the materials and labour that they were supposed to provide.  While we were preparing the project, we therefore embarked on a series of meetings in each of the villages in order to gain the support of the communities in the implementation of the construction programme.  There was a lot of enthusiasm among the villagers for the programme once they realised that by assisting the project they would be providing their children with improved primary schools as even among rural communities there was a recognition that education was essential for their children if they were going to be able to improve their lot in life.  These meetings continued during the construction of the school buildings and every month I chaired a public meeting in each of the villages attended by the villagers, the school committees, the village chiefs and in some villages the paramount chief at which progress and problems were discussed.  These meetings proved to be invaluable as ways of imparting information and of sorting out problems and close relationships were formed between the project team and the village communities.

Hand-tools being handed over to a village committee.

We trained teams of labourers and skilled workers such as masons and carpenters in each village and these were paid every month as well as receiving food rations.  After our meetings with the village communities, most of them worked hard to supply the large quantities of local materials that were required but in some cases suitable materials were not available locally and the PEU had to purchase and transport them, particularly sand and large aggregate.  Most communities did supply adequate quantities of bush-sticks for scaffolding and roof construction but it proved impossible to obtain sufficient timber in the villages to make all of the doors and shutters and timber therefore had to be purchased.

Using the designs developed previously by myself, varying numbers of four types of standard buildings were constructed at each primary school: 2-classroom units, 3-classroom units, multipurpose units with a single classroom and a double classroom for large meetings and 2-workshop units.  See below for drawings of the standard buildings.  VIP-latrines were constructed at each school site together with wells for drinking water equipped with good quality hand-pumps.  The access roads to most of the villages were improved, new culverts were built and one bridge over a river that collapsed during the school construction was also re-built.

The furniture designs that I had developed (which will be covered in a later post) were also used with some changes to the sizes which were made after an anthropometric survey was carried out of primary school age children in the project villages.  The classrooms were designed for 44 pupils using double desks and individual chairs in order to give some flexibility in the use of the classrooms and in the teaching methods used.

Photos of typical school buildings are shown below.  More details of the construction of the buildings will be given in the next post.

 

Sierra Leone 4

By the early 1980s, Sierra Leone’s economy was in free-fall 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 was then offered a two and a half year local consultancy by the World Bank to develop designs for primary schools that could be built by rural communities.

The overall objective was to design standard 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; 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.

The traditional building materials that were still in common use in the country included sun-dried mud blocks and ‘wattle and daub’ (ie bush-sticks with mud infill) for walls and thatch including ‘bamboo thatch’ (roof tiles made from palm leaves stitched together) for roofs.  The ‘improved’ materials in most common use were sandcrete (sand and cement) blocks and ‘corrugated iron’ (ie profiled steel) roof sheets.

The country lacked almost entirely two basic building materials: clay suitable for making fired bricks and lime.  This meant that lime and cement (or the clinker to make cement) for building had to be imported and were thus expensive, especially in the rural areas.  One 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 while the other task was to develop designs for buildings and furniture that could be easily constructed using these materials or techniques.

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 assistance to do so in the form of designs and technical assistance.

Over the two year assignment I worked with a number of individuals, agencies and communities, developing primary school designs that would be simple and economic to build and that would require the minimum of technical assistance.  These included a VSO (UK volunteer), several Peace Corps (US volunteers), a Catholic priest, a rural development project, an international NGO and a community activist who wanted to construct a primary school in his village and all-in-all, twelve classroom buildings were constructed.

In order to reduce the amount of cement used in the buildings I investigated the use of a number of traditional and new/improved materials for the construction of walls and roofs.  These included the use of: sun-dried mud bricks with improved foundations; stabilised-soil blocks that used a small percentage of cement; the production of cement locally from rice-husk ash and fibre-cement roof tiles and sand-cement floor tiles made on imported machines.  The British High Commission in Freetown kindly donated a stabilised-soil block-making machine and a machine that could be used for making fibre-cement roof tiles and sand-cement floor tiles.  The former was the BREPAC machine that had been developed by the Building Research Establishment in UK and the latter was made by Parry Associates also in UK.  I also had use of ‘cinva-ram’ machines for making stabilised-soil blocks on some sites.

I reviewed the types of classroom furniture that were in use at the time and experimented with new designs for furniture.  These were based upon a design developed by UNESCO in the 1970s and were constructed of 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 with no complicated joints using locally available timber.  Details of the furniture will be given in a future post.  I developed a design for a standard classroom that could accommodate 44 pupils using double desks and single chairs.

The classroom buildings 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.

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.

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.

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.

It quickly became obvious that the real design problem was again, 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.

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.

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 they must have some protection from heavy rain such as large roof overhangs and rendering at the base of the walls and they must be used with stone or concrete foundations.

Producing blocks using the ‘BREPAC’ machine

Classroom building constructed of stabilised-soil blocks manufactured using the BREPAC machine, under construction.

Several classroom buildings were constructed using sun-dried mud bricks and, providing these are constructed on stone or concrete foundations and the walls are protected from direct rainfall with large roof over-hangs, these can be very successful.

Classroom building constructed using sun-dried mud bricks.

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.

Fixing fibre-cement roof tiles (health and safety?!).  Note that we had to use milled timber purlins because of problems using bush-pole purlins with these tiles.

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.

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.

A further lesson concerned the involvement of communities in the construction process.  As noted earlier, twelve classrooms were eventually constructed and the most successful of these were the ones that originated in the communities and where local people were involved in the implementation of the construction process.  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.

Community members at one site making sun-dried mud bricks for a classroom building.

The construction of the classroom buildings also proved that a degree of technical assistance of some kind was necessary in order to produce good quality buildings 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 assistance there was, there was little chance of success if the community had to bear the entire or the greater part of the cost of construction themselves.  Building materials were even then so expensive (even with the reduced amounts of cement and other materials that were used) that small, farming communities could not afford to construct a building such as a classroom without some financial assistance.

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. These designs were later 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 will be the subject of the next post.

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.

What I did not stress enough in the original version of this post is my conviction that most of the concrete used in the construction of simple rural schools and health centres in Africa and elsewhere is simply a waste of precious resources and quite unnecessary.  The concrete used in most of these buildings is poor quality, many of the beams and columns are so under-sized as to be structurally useless and the columns are rarely if ever tied into the wall panels.  It is my conviction therefore that these types of buildings (unless of course they are constructed in seismically-active locations) do not require a concrete frame and in fact are stronger if built without one and I think that the schools illustrated above (and the school buildings constructed in the Bo project which will be discussed later) support this.

Note: most of the drawings shown above (ie the ones with page numbers) have been taken from my final report on the consultancy and the second section of this report took the form of a construction handbook showing how to construct a classroom building using the materials and techniques shown in the report.  Copies could be available for anyone interested!

 

 

A House in Freetown

In 1982, my wife and I decided that we would be staying in Freetown for the foreseeable future and thought therefore that it would be best if we built a house.  We purchased some land on the side of a hill below Hillcot Road on the outskirts of town and I embarked on the design of the house.

The site sloped quite steeply down to the south with views over Freetown and consisted mainly of granite rock with patches of top-soil.  It was important therefore to design the house so that there was the minimum of excavation for foundations.

The climate in Freetown (which is only 8° north of the equator) is hot and humid for most of the year with heavy rains during the rainy season which lasts from June to the end of September.  The house had to be designed in such a way therefore that it could cope with this climate without having to use air-conditioning while still providing a comfortable living (and sleeping) environment.  It was therefore located across the top of the site facing south in order to reduce solar penetration into the rooms and was one-room deep in order to maximise cross-ventilation, with the result that it was long and narrow.

I decided to place the main living and sleeping accommodation on the first floor to make the most of the breezes from the south-west and of the views to the south and also to improve security to these areas.  All living and sleeping rooms had louvred shutters with mosquito screens (there were no glazed windows in the house) to provide maximum ventilation.

Initially on the ground floor there was a double car-port under the first floor sitting room; the main entrance into the house; a spiral staircase leading up to the first floor; a large store; two bedrooms and a toilet and separate shower.  The bedrooms had louvred shutters to both sides of the rooms to provide cross-ventilation and ‘clostra’ block screens externally to provide security.

On the first floor, the spiral staircase led to a large (20’ 0” x 30’ 0”) sitting room with a large balcony in front (11’ 0” x 30’ 0”) and this balcony became our main living space.  A long kitchen divided the living accommodation from the first floor bedrooms.  It was open at both ends with clostra blocks for ventilation and at the northern end there was a charcoal-burning stove (with a hood and chimney) for use when bottled gas was not available (which was quite often!) and this proved to be invaluable.  Past the kitchen was a room that was originally intended to be a study/office, a toilet and then our bedroom with an en-suite shower.  Both of these rooms had louvred shutters to both sides.

Externally on the ground floor there was a utility room and toilet and a tank-stand with a hot water tank which was supplied by a solar water heater.  I explored the use of solar panels for providing electricity but at that time they were too expensive to use.

Soon after we moved in, I constructed an office on the ground floor in place of one of the car-port bays and converted the first floor study into a bedroom for our children.

The construction of the house was a mixture of reinforced concrete, rendered blockwork and timber-framing with external cladding of ‘colour-bond’ roof sheet panels.  A reinforced concrete ring beam at first floor level was supported on blockwork walls at the bedroom end and on large, round reinforced concrete columns anchored into the rocks at the living room end.  The first floor was constructed of timber joists sitting on a rebate in the concrete ring beam and supporting tongued and grooved timber boarding.  The first floor walls at the bedroom end were of rendered blockwork with louvred shutters and roof-sheet panels below.  The sitting room and balcony were constructed of timber frames with louvred shutters to one side of the sitting room and large sliding doors opening on to the balcony.  The balcony had full-height open timber screens to three sides for ventilation and security and the end wall was timber-framed with roof-sheets as the finish externally.

At the bedroom end, the first floor cantilevered out over the ground floor in order to provide some protection from the rain to the ground floor walls and all of the first floor rooms had very large roof overhangs (6’ 0”/1.8 metres) to provide protection to walls and windows from the sun and rain for both comfort and to reduce maintenance costs.

The combination of large roof overhangs and rooms with large amounts of cross-ventilation provided very comfortable living and sleeping spaces and we never felt the need for air-conditioning.  The large roof overhangs also reduced the need for maintenance as can be seen from the fact that, when I visited the house some 25 years after it was built, the paintwork still looked good even though it had never been re-painted!

All of the large aggregate for the concrete was broken by hand on site.  The timber used for the timber framing, the roof, the timber window panels and the first floor was sourced from a small timber mill up-country and was a very hard wood that is resistant to termites and is used for railway sleepers in Ghana.  Very hard and very difficult to work with but will last for ever!

The house was constructed using direct labour.  I employed artisans and labourers to do most of the heavy work managed and supervised by myself.  I did a lot of the work myself such as laying and fixing all of the tongued and grooved floor boards, fixing the roof sheets, the first-fix plumbing, tiling the walls and most of the painting.  Every architect should if possible build a house as it teaches you a lot, especially in developing countries, about what is and what is not possible!

Below you will see the original drawings, progress photographs and photographs of the finished house.

Site plan

Ground floor plan

First floor plan

Section through sitting room, balcony and car-port

Section through the entrance and staircase

Section through kitchen

Section through bedrooms

Section through bathrooms

View from below the bedrooms during construction

Bedrooms under construction with the water tank stand to the right

Timber framing started to the living room and balcony

Timber framing in progress to the living room and balcony

Floor boards in progress in the sitting room

The architect fixing roof sheets!

The house from the south after completion

The entrance to the site after completion of the house

The bedrooms from below

The bedrooms from the north side

The architect in his office

The children with friends in the sitting room

and on the balcony

The house a few years after construction

Sierra Leone 3

In April 1982 I was living in King Tom, Freetown in a house facing on to the sea.  I woke one morning to see a North Sea ferry (with machine-guns mounted on its prow) steaming across the bay and this was the first of many ships (including SS Canberra) that berthed in Freetown in the next couple of weeks.  The Falklands conflict had started and Freetown’s deep-water port (the only one in West Africa) and its airport at Lunghi across the river estuary played very important roles in the conflict.  In fact it is probably not an over-statement to say that, without Freetown, the UK government would have had great difficulty in supporting the battle to win back the Falklands.  Ships and planes were re-fuelled and loaded with supplies there (including sand for sand bags and beer, which was in very short supply in the city for the duration of the fighting) but you would not know this if for instance you looked up the conflict on Wikipedia which omits all mention of the role that Sierra Leone played.

To show her gratitude to the Sierra Leone government for its help, Thatcher gave the country two development projects: one that supported the renovation of the Ministry of Public Works’ mechanical workshops in Freetown and another for the construction of a Certificate Training Centre for agricultural extension workers at Njala University.  We had been commissioned in 1977 by ODA (now DFID) to renovate an existing training centre for agricultural extension workers at Makali and we were given the design and supervision of the Certificate Training Centre as an extension of this contract.

The Certificate Training Centre was constructed on a gently sloping site on the top of a hill about half a mile from the main campus of Njala University (the country’s agricultural university).  The overall design was similar to that of the Paramedical School with administrative offices, teaching spaces, dormitories for 90 male and female students and three staff houses.

The Centre’s teaching and administrative facilities were again designed around a central covered route with links to the individual buildings.  The covered way ran north-south with the buildings perpendicular to it so that all of the buildings were oriented north-south thereby reducing solar penetration into rooms.  Changes of level from one end of the site to the other were taken care of by steps in the central covered way.  The administration building, dining room and kitchens were at the centre of the covered way, near the entrance to the site, with the teaching buildings at one end of the covered way and the student dormitories at the other end.

The budget for the construction of the Centre was limited (Thatcher was not that grateful!) and a simpler and more economic solution to the roof construction had to be found than that used at the Paramedical School.  All buildings were constructed of load-bearing blockwork, plastered and painted with RC ring beams but no RC columns.  The planning grid for all of the buildings was 10’ 0” and the simplest and most economic roof construction that I could come up was the use of timber purlins (6” x 2”s spanning 10’0” with no rafters) supported by the block walls and where larger spans were required as in the teaching rooms and the cafeteria, steel lattice portal frames.  There were large roof overhangs to protect windows and walls from the sun and rain but it was not possible to ventilate the roof space.  There were no roof gutters and again rainwater was collected in storm-drains around the buildings and in a main drain along the central route.

All buildings (including the dormitories and staff houses) were single-storey and accessed either from access verandas or from the ends of the buildings and all buildings (except the dormitories; see below) had full-width windows (aluminium louvre units) between cross-walls on both sides of the buildings in order to provide maximum cross-ventilation.

The dormitories were planned around courtyards with the central covered way on one side, two dormitory buildings on the two sides perpendicular to the covered way and another building housing toilets, showers and a student kitchen/dining room closing the courtyard on the side, opposite the covered way.  The dormitories had study-bedrooms for two students similar to those at the Paramedical School with full width louvre windows on the outside walls and full-height timber louvre doors and fixed panels on the access veranda side, again to provide maximum cross-ventilation.

This project again illustrated my main concerns when designing educational (and other) buildings in tropical countries: simplifying construction and reducing costs by reducing the use of reinforced concrete; maintaining the north-south orientation of buildings in order to reduce solar penetration into rooms; providing large roof overhangs again to reduce solar penetration and also to reduce maintenance costs; providing maximum cross-ventilation in order to maximise comfort; providing high, sloping ceilings again to maximise comfort and in the larger institutions, using a structural grid for all buildings in order to standardise construction and provide a sense of order within the group of buildings.

Central covered way

Typical link to covered way

Administration building

Access veranda to administration building

Typical elevation showing louvre window units

View of dormitory courtyard with toilet block at rear

Timber entrance door and screen to study-bedrooms

Kitchens: ‘wood-fired’ kitchen to the left and ‘modern’ kitchen to the right

Interior of dining room showing steel lattice portal frames

Another view of the ‘word-fired’ kitchen and dining room

Staff house: rear of bedroom wing

Staff house: front veranda

 

 

Sierra Leone 1

In 1975/76 after the end of the war in Vietnam, the economy of Zambia (which at that time was based upon copper, the price of which had dropped drastically) collapsed and with it the construction industry.  Suddenly we had no jobs in the office and this meant that I had to look for another job!

About a year previously I had noticed a job in Sierra Leone that was being advertised.  It had looked like an interesting job so, without much hope of success I sent a telegram (!) to the firm enquiring as to whether they had still had need of an architect in their office.  I received an immediate reply stating that the architect who had taken the job had left the office without warning and that they needed someone immediately.  So, within a month, I found myself in Freetown!

My first job was to complete the documentation for the 2^nd IDA education project (extensions to rural secondary schools) and get construction started.  I then took over the design and supervision of most of the projects that came into the office.  I stayed there for nine years and managed a great many jobs for a variety of mainly international clients such as the World Bank, the EU and DFID (or ODA as it then was).   The jobs ranged from a paramedical school to agricultural extension workers training centres, teacher training colleges and secondary and primary schools.

The documentation for the IDA project had supposedly been completed before I arrived in the country.  There were however serious problems with both the designs and the documentation which took a while to sort out and even then it was not a really satisfactory project.  One thing that struck me was the amount of reinforced concrete (RC) used in the design of the schools (and in other building projects in the country) compared to buildings generally (especially in single-storey buildings) in Zambia.  This is very noticeable in most West African countries and I can only put it down to a difference of culture: that of Britain in East and Southern Africa and France in West Africa (and of the French, Lebanese, Italian and Swiss contractors there).  Reinforced concrete construction is expensive and quite unnecessary in most simple, single-storey buildings (a topic that I will return to in later posts) and I tried to reduce the amount of reinforced concrete, to simplify construction and to reduce costs in all of the projects for which I was responsible.

Two projects that I carried out in the early 1980s show how my ideas for the design of medium to low-cost educational buildings for the tropics were developing.  These were the Paramedical School in Bo that was funded by the EU and the Agricultural Extension Workers Training Centre at Njala University funded by ODA/DFID (which will be covered in a later post).  Unfortunately I do not have any drawings for either of the projects but the photographs (the quality of which is not very good) illustrate most of the points that I wish to make.

The Paramedical School was built on a very large, sloping site outside of Bo, a provincial town in the east of the country, 150 miles from Freetown.  It was a self-contained campus with administrative offices, teaching spaces, dormitories for male and female students and a number of staff houses.  The offices, classrooms and student dormitories occupy one part of the site with staff houses in another part.

The school facilities were designed around a central covered route with covered links to the individual buildings (a ‘pavilion’ layout).  The covered way ran north-south with the buildings perpendicular to it so that all of the buildings were oriented north-south thereby reducing solar penetration into rooms.  Changes of level from one end of the site to the other were taken care of by steps in the central covered way and changes of level across the site by steps down to buildings on the lower side of the covered way.  The admin buildings were at one end of the covered way, near the entrance to the site, the teaching buildings were in the centre and the student dormitories were at the other end. There were possibilities for future extensions in three directions from the central covered route.

The planning of the buildings was based on a grid based on the span of the lightweight lattice steel purlins which were supported either by cross-walls or for the larger, teaching spaces, steel portal beams supported on block-work piers.  The lattice purlins were made of 12mm reinforcement rods welded together to form a hollow pyramidal shape similar to those used in the University Village in Zambia but they were used the other way up so that the top 2 rods supported the roof sheets and the bottom rod supported the ceiling battens.

The admin and teaching buildings (and staff houses) were all single-storey and the dormitories were two-storey.  All buildings were constructed of load-bearing blockwork, plastered and painted with RC ring beams but no RC columns.  All buildings had large roof overhangs to reduce solar penetration into rooms and also to keep the rain off of the walls and windows in order to reduce maintenance costs.  There were no roof gutters (which get blocked and provide breeding places for mosquitoes) and rainwater was collected in storm-drains around the buildings and in a main drain along the central route.

The dormitories had 2-person study bedrooms on two floors accessed from verandas and first floor balconies with communal toilets and showers on both floors and a communal sitting room and kitchenette on the ground floor.  All rooms had full width louvre windows on the outside walls and full-height timber louvre doors and fixed panels on the access veranda/balcony side in order to provide maximum cross-ventilation.

The office and teaching buildings were accessed either from access verandas or from the ends of the buildings and had full width louvre windows between cross-walls on both sides of the buildings in order to provide maximum cross-ventilation.

Long-span profiled steel sheets were used for roofing and the ceilings followed the slope of the roofs providing additional height to all rooms.  The walls or beams at the eaves stopped at the underside of the purlins and the gaps between the tops of the walls or beams and the undersides of the roof sheets were closed with mesh panels that allowed the ceiling spaces to be ventilated.

This project illustrated what were then my main concerns when designing educational (and other) buildings in tropical countries: simplifying construction; reducing costs by reducing the use of reinforced concrete;  maintaining the north-south orientation of buildings in order to reduce solar penetration into rooms; providing large roof overhangs again to reduce solar penetration; reducing maintenance costs; providing maximum cross-ventilation in order to maximise comfort; using sloping ceilings in all rooms to provide greater volumes again to maximise comfort; and in the larger institutions using a ‘pavilion’ layout with covered links to all buildings together with a structural grid for all buildings in order to standardise construction and provide a sense of order within the grouping of the buildings.

The central covered way under construction.

The central covered way when complete.

Covered way showing steps down to teaching buildings on the lower side.

Classroom building under construction; note the lattice purlins, the single purlin at the centre of the roof and the light, steel portal beams.

Inside an office.

Dormitory building showing entrance.

Dormitory building showing communal ground floor lounge.

Dormitory building.

End of covered way.

Staff house.

 

A secondary school project in Zambia

Zambia Secondary Schools Project

Chama Secondary School from the air

I arrived in Zambia in September 1970 and was given the job of completing the detail design, producing the working drawings and supervising the construction of three, large (600+ pupils) secondary boarding schools, all situated in the rural areas.  One school was located at Chongwe, 30 miles from Lusaka, one was at Pemba, 150 miles from Lusaka and the third was at Chama, 550 miles from Lusaka.

Zambia is located in the tropics but as the majority of the country is at an altitude of around 1,000 to 1,500 metres it does not experience unduly high temperatures except in the valleys of the great rivers (Chama is located at the north end of the Luangwa valley and the first time that I visited the site it was over 40°C in the shade!).  There is a wet season lasting from October to April and a dry season for the rest of the year.  October is usually the hottest month and July the coldest.  These climatic factors mean that buildings should be designed to keep the sun out of rooms and to provide good cross-ventilation in order to provide a comfortable environment without resorting to mechanical means.  Glare from both the sky and the ground in the dry season are other factors that have to be designed for.

The World Bank was at that time implementing a large secondary school renovation and construction programme (approximately 120 schools) which was being managed by a Norwegian firm of consultants.  The approach that they took was, for the time and place, very high-tech with the schools being constructed in the main of pre-fabricated fibre-cement components assembled on site on concrete floor slabs.  The documentation system they used was also very new using CI-SfB coding, something that had never been used in Zambia before and which resulted in a multitude of drawings and other contract documents.  The end result was that the programme took a very long time to complete and a few contractors went bankrupt due to the fact that they did not understand the documentation.

Our firm was given three schools that the government wanted built but which the World Bank had refused to fund.  We therefore had to work to a very tight budget and keep costs as low as possible while at the same time ensuring that the schools would be simple to construct in remote locations (the contractor who eventually won the Chama school contract was based in the Copperbelt which gave him a 1,800 mile round trip to the school site and back to his base!).

It should be noted that Zambia is land-locked and that the only locally available building materials at that time were aggregates, bricks, cement and locally produced fibre-cement roof sheets.  There was no local timber and other building materials had to be imported by road from either Dar-es-Salaam or South Africa at great cost.  Our approach therefore was to use traditional construction methods and local materials as much as possible, rationalised in order simplify construction in remote areas.  The floors were of minimum thickness concrete slabs reinforced with mesh and with sand-cement screeds as a finish; the walls were of either local brick or sand-crete blocks manufactured on site reinforced with brick-force in the joints and the windows were louvres to give maximum cross-ventilation at a reasonable cost.

The main problem we had to resolve was how to construct the roofs.  These had to be simple and economic to construct as well as being easy to transport given the long distances to two of the sites.  They had also to be functional in that, as well as providing protection to the buildings from the elements, they had to provide protection from both the sun and the rain to walls and windows in order to maximise comfort in the rooms and reduce maintenance costs.

Analysis of the design brief had shown that the basic design module for the teaching spaces would be 8 metres with a 4 metre half-module where necessary for instance in service areas such as toilets, showers, stores, etc.  The schools were therefore designed on a 4 metre module with structural walls at 4, 8, 12, etc metre centres.

As all structural timber had to be imported and was very expensive (and liable to attack from termites), it was decided to explore ways of using steel for the roof structure.  Steel was at the time priced on weight and therefore if a very light structural system could be devised it was likely that this would be less expensive than using timber.

Working with our engineers and a local builder of truck bodies (who had the necessary bending presses for bending the steel sheets) we developed a very light, long-span lattice purlin which did away with the need for rafters.  The purlins were constructed of pressed steel sections: the top member was an inverted ‘U’ and took the hook-bolt fixings of the roof sheets; the bottom member was a ‘top-hat’ section where the central ‘U’ shape provided space for electrical conduits and the ‘wings’ on either side supported the pressed metal ‘T’ sections that in their turn supported the ceiling panels.  The lattice members welded between the top and bottom sections were simple pressed steel ‘L’ sections.  The lower member of the purlins also provided a fixing position for the top of the louvre units that were used for windows.  The basic purlin was 4 metres long and these could be bolted together (through end plates) to form any length based on the 4 metre module.  See sketch for details.

Pressed steel purlin

This system of roof construction proved to be very economic, very simple to transport even to remote sites and very simple to erect; two men could easily lift an 8 metre long purlin into position.  It also meant that there was no need for expensive concrete ring-beams or lintels and therefore the only concrete used in the buildings was for the strip foundations, the floor slabs and for filling the pockets in the tops of the walls around the ends of the purlins.

The purlins were spaced at 1.35 metre centres, the maximum possible for the fibre-cement roof sheets and a specially-made curved roof sheet was designed for use over the centre of the buildings.  This made it possible to omit one central purlin reducing the overall roofing cost still further.  See section.

Because the purlins were 30 centimetres deep and had an open lattice framework web, this meant that the roof space could be used for services and could also be ventilated which helped to reduce the temperature in the rooms.  Large roof overhangs (1.5 metres deep) were provided in order to keep the sun out of rooms from 8 am until 4 pm and to reduce glare from the sky and the external purlins were supported on projecting walls on the 4/8 metre module.  See section.

Louvre windows and roof ventilation

 

The school buildings were designed as standard buildings and consisted of: a 3-classroom building; an arts and crafts building; two laboratory buildings; a library; a metal workshop; a wood workshop; a social studies building; an agricultural workshop; a medical building; a staff room; an assembly/dining hall/kitchen and dormitories.  For the school at Chama which was very remote, we also designed and built staff houses. See typical building layouts below.

The layouts of all three schools were similar and were based on a ‘pavilion’ layout (which I discussed in an earlier post) that gave flexibility in the layout, allowed plenty of space between buildings, allowed for differences in level across the sites and also allowed for future expansion.  All buildings were oriented to face north/south in order to reduce solar penetration into rooms as much as possible and all buildings were single-banked in order to maximise cross-ventilation.

A series of three or four covered ways running north/south linked all of the buildings and these routes also carried services such as water, electricity and the main storm-drains.  All of the teaching buildings had front verandas that were linked to the covered ways and gave access to the various teaching rooms and the dormitories had direct access from the covered ways.

The schools were zoned with dormitories at one end and teaching spaces at the other with the assembly/dining hall and an external ‘school square’ in the middle of the school.  The noisy teaching buildings such as the workshops were placed at the outside of the teaching zone.

This was my first project in Africa and I learned a lot very quickly.  I had very good mentors in the persons of the two partners in the firm who had both lived and worked in southern Africa for a long time.  I was also lucky to have three experienced and knowledgeable contractors from who I again learned a great deal about what you can and cannot do in situations where good materials and skilled craftsmen are scarce.

 

All in all, I learned a great many lessons from designing and supervising the construction of the Zambia schools and with regard to school design these were that:

• The whole school environment should be considered not just the classrooms;
• The buildings should be accessible to all, appropriate in scale and attractive to the users;
• The buildings should be arranged in the most economical way taking into account orientation, the slope of the site and the prevailing climate;
• The layouts should incorporate courtyards and other external spaces for recreation, teaching and learning;
• The layouts should allow for flexibility and future expansion and promote safety and security.

With regard to general design for buildings in tropical, developing countries the main lessons were that:

• The designs should respond to the local climate, topography and any potential hazards (such as earthquakes, cyclones, etc) and most importantly,
• The construction should be simple, cost-effective and aim to minimise maintenance costs.

The climate is a major influence affecting the comfort buildings in tropical countries and the layout and design of any building needs to reflect this.  The key issues are that:

• correct orientation of buildings in the tropics is essential if the sun is to be kept out of rooms and off main walls although in warm, humid climates it might be necessary to modify the orientation in order to face the buildings into the prevailing breeze;
• elements of building design, such as roof overhangs, window openings and roof construction will affect ventilation, heat and light levels in the buildings and need to be properly considered, and
• the use of planting to provide shade and help to keep buildings cool is often very cost effective and should not be overlooked. Trees can be planted at a safe distance to buildings to provide shade and climbing plants can be trained over verandas and roofs if these do not compromise the need to collect water from the roof.

With respect to construction, buildings should be simple to construct, respect local building traditions, use locally available materials and simple, locally understood construction techniques. They should also be designed to reduce maintenance costs as budgets for maintenance are not usually forthcoming in developed let alone developing countries.  Anything that will reduce the need for or the cost of maintenance should therefore be considered even if it increases to some extent the capital cost of the building. It should also be understood that without a simple and economic roof design it is very difficult to construct low-cost buildings and the design of the roof also plays an important part in designing for climate in locations where it is important to keep the sun out of rooms and off walls.  Large roof overhangs are also useful in keeping the rain off of walls and in reducing maintenance costs.

The knowledge that I gained from this project has stood me in good stead over the years, has informed most of the projects that I have worked on since and continues to do so.

 

Introduction

This blog should be of interest to architects or similar working in tropical countries and involved in the design of low-cost, ‘appropriate’ buildings.

I am, I think, one of the last of the generation of European architects who had the opportunity to live and work in Africa in the 1960s and 70s and who gained valuable experience from a previous generation of architects who had long worked in the tropics.  Members of that generation were still working in tropical countries while others were by then involved in setting up and running courses in universities in a number of countries in the design and construction of low-cost tropical buildings.

Sadly both the practitioners and the academics (and their courses) have now largely passed on and opportunities for new generations of architects (both western and locally-based) to gain knowledge of and experience in the design of low-cost tropical buildings are few and far between.  Further, few young architects in ‘developing’ countries seem to be interested in solving the problems of designing and constructing this kind of building and young architects from more developed countries who are interested in this sort of work have little opportunity to gain the necessary experience and expertise.  While there are some NGOs that are working on construction projects in tropical countries their staff (whether architects or not) seem to have little real experience or knowledge of the problems of designing and constructing low-cost and appropriate buildings.

I am going to try therefore to provide the benefit of my 45 years of experience of working in tropical countries on the design and construction of low-cost construction projects to anyone who might be interested.