Some principles of designing for safety
Designing for wind resistance
Designing for earthquake resistance
• Select a sheltered site; avoid long and narrow (<6
m) streets; position houses in a staggered way rather
than in rows; create wind breaks by planting trees,
hedges etc.;
• Make buildings heavy, so it is more difficult for the
wind to blow them away;
• Use a compact shape, with low walls, to present
minimum obstruction to winds;
• a hipped roof, pitched at 30-45º, with small eaves to
prevent uplift; avoid gables, as they may be pushed
inwards;
• If a veranda is required, separate veranda frame and
covering from the main roof;
• Tie roofing sheets well to the roof frame; flying sheets
can be lethal; in the case of gci sheet roofing, provide
overlaps of 2.5 corrugation, and closer spaced ‘U’
bolts along ridges and external walls;
• Reinforce structural connections with ‘hurricane
straps’;
• Make solid foundations, well anchored to the ground;
• Provide strong structural joints and fixings, especially
between walls and foundations, and walls and roof;
use diagonal bracing;
• Give walls a rough finish to reduce wind suction;
• Position openings centrally and away from corners
and intersections; provide openings on both sides of
rooms, so that the wind can eventually pass through,
rather than lift the roof;
• Ensure all windows can be closed; avoid louvres - if
they are essential, provide storm shutters or board
them up before storms.
• Select a solid site; avoid landfills, flood plains and
steep slopes;
• Make buildings light to reduce the horizontal forces
caused by earthquakes;
• Make roofs light to avoid them pushing walls sideways
and falling-in on people;
• Design compact buildings with a symmetrical shape
and closely spaced walls in both directions. If that
cannot be done, design them in separate blocks;
• Separate adjacent small buildings by at least 75 mm;
• Avoid gables, they may fall inwards;
• If buildings have more than one floor, opt for similar
floor shapes and designs;
• Position the foundations on rock or firm soil, avoid
stepped foundations;
• Provide strong joints between structural components;
use a ring beam and a plinth beam where possible;
use bracing at corners;
• If masonry walls are used, create good bond
especially at corners and intersections;
• If concrete pillars are used, lap vertical
reinforcements mid way between floors and not just
above floors;
• Keep openings to a minimum, well distributed over
the building and within walls; keep them centrally
positioned, at least 60 cm away from the inside of
corners and intersections and from the nearest other
opening
Designing to cope with floods
Designing to cope with landslides
• Avoid sites close to rivers and other waterways that
are known to flood;
• Provide for good site drainage and good waste
management, as waste may block waterways;
• Plan for measures, such as small dams or gabions
that can reduce the speed of water;
• Plan any new infrastructure very carefully. Some,
such as road or railway embankments, may have
devastating effects by re-directing flood waters;
• Lift buildings onto stilts or raised platforms - where
the latter is used, a larger platform for a cluster of
houses is preferable over single platforms, to reduce
the effect of erosion;
• Provide deep foundations that keep buildings in
place even in strong currents, eventually include a
ring beam at plinth level. The minimum depth should
be 600 mm in solid soils - if stones are used, select
angular, not round ones;
• Avoid the use of soil in foundations or walls that may
be reached by flood waters. These lower sections of
walls should be made of more durable materials that
can resist the shocks of debris floating in water;
• Protect organic materials such as timber and bamboo
from the effects of humidity.
• Avoid building on steep slopes do not make steep
cuts in slopes to make space for infrastructure or
housing; keep any cuts shallow, as steep cuts may
become unstable;
• Drain slopes well, as they can become unstable and
lose bearing capacity when soaked. For the same
reason, avoid the use of soakaways, e.g. for sanitary
systems or used household water, on slopes. Use
stepped drains to reduce the speed of downward flow
of water;
• Avoid blocking natural drainage ways with buildings
or infrastructure;
• Avoid stepped buildings where possible; create
terraces for small buildings, but avoid deep cuts and
fills; keep any infill at the lower end to a minimum,
and stabilise this well;
• Foresee retaining walls to retain the slope above
terraces, and any infill at the lower end;
• Reduce erosion by planting appropriate vegetation on
slopes.
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