School buildings in developing countries
Practical Action
Galvanised corrugated iron - this is widely used as a low cost roofing material in
developing countries, particularly in Africa. However, this material has a number of
limitations including that in humid conditions it corrodes and might have a lifetime of
only 5 - 10 years. Also, it has rapid heat gain, so the indoor space underneath can
become uncomfortably hot quite quickly during the day, and heavy rain on the roof is very
noisy, making it difficult for children to hear each other and the teacher. With the
thickest gauge of sheets, or ones that are specially coated, these problems would not be
so great but their costs would be very much greater than for the standard sheets. Again a
ceiling would produce significant improvements, especially in giving better acoustics.
Asbestos cement - the use of corrugated asbestos cement sheets in buildings has been
banned in most Western countries, due to the lung cancer risk from asbestos fibres, but
these sheets continue to be produced and used for building in some developing countries.
Although the risk from asbestos cement is primarily to fabricators and builders using this
material, rather than building users, as children's health is involved it is strongly advised
not to use asbestos cements boards and sheets in school buildings. In some Western
countries safer alternative cement-based boards and sheets are produced, generally based
on using cellulose fibre for reinforcement. However, it is not known whether any of these
materials are yet produced in developing countries.
Micro concrete roofing (MCR) tiles - MCR technology is now well-established in a number
of countries and small complete production plants can be bought for as little as £1000,
so for a programme building a number of schools in an area it could be practicable to
obtain such a plant to produce tiles for all the schools. MCR tiles and semi-sheets are
relatively durable if well made and offer some protection from thermal gain and the noise
of heavy rain or hail falling on the roof. Compared with some other materials such as
galvanised corrugated iron the roof is heavier, so a more complicated and expensive roof
structure is required, and the installation of the tiles is more complicated so a level of
skill is required. These additional costs, however, can be offset against the greater
durability of MCR tiles.
Fired clay tiles - the use of these tiles is now somewhat limited and generally confined to
areas where they are produced. Whereas a number of types of clay can be used for fired
clay bricks, only a relatively few clay deposits have the necessary characteristics for the
production of satisfactory fired tiles, so the availability of these tiles is by no means
widespread. A number of shapes of clay tile have been produced. One of the most
common is the rounded Bangalore type. Generally roofs of fired clay tiles are even
heavier than for MCR, so there is the added cost of the roof structure to consider. Also,
as clay tiles require a high-energy input to fire them they are not particularly
environmentally benign, nor low in cost. Their main advantage, if well produced and
properly installed on the roof is their high level of durability. A roof with these tiles would
be good for 20, if not 50, years before the tiles need to be substantially replaced.
Domes, vaults and corbelling of fired clay bricks or stabilised soil blocks - the use of
these techniques offers the advantage that a roof structure is not required. However, the
roofs themselves would be heavy, so it
would be important to ensure that the
walls are strong enough to support
these roofs; and additional
strengthening, e.g. the use of a
structural frame in the wall, might be
required. The use of these techniques
has most potential in areas where there
is a tradition of building domes, vaults
and the use of corbelling. In other
Figure 2: Corbelling
areas masons might be reluctant to use
them and could need a lengthy period
of trials and familiarisation. The use of domes, vaults and corbelling is generally best
suited to relatively dry climates without significant night frosts, unless a protective
external coating of render is applied, as the mortar joints between the bricks or blocks
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