Flood resilient construction uses methods and materials that
reduce the impact from a flood, ensuring that structural integrity
is maintained, and the drying out and cleaning required, following
inundation and before reoccupation, is minimised.
Concrete is inherently water resilient and
entirely suitable in a construction designed to be either
waterproof, as required for water barriers, or water resilient. The
extent to which the structure keeps out water depends on the
specification of the concrete itself and its design details, corner
junctions for example.
Categorisation of the flood resilient
properties of various construction materials and guidance on
appropriate flood management strategies is provided in
the Department of Communities and Local Government publication
Improving the flood performance of new building: Flood resilient
A water exclusion strategy, or resistance, for
low depth flooding, is designed to prevent floodwater entering the
building and minimise the impact of floodwaters and to give
occupants more time to relocate ground floor contents.
A water entry strategy, or resilience, for
greater flood depths includes measures incorporated into the
building to reduce the impact of floodwater on the property once
water has entered.
Insitu and precast concrete has low
permeability so resulting in minimal damage or deformation from a
flood. It is appropriate for use in buildings that require either a
water exclusion strategy or a water entry system, where other
construction techniques could incur structural damage due to
excessive differential pressures.
Summary of water exclusion strategy
- Concrete foundations: provide a barrier to
water entry into the wall cavity.
- Floors: Ground supported concrete slabs of
min. 100mm thick can prevent loss of structural integrity due to
uplift pressures due to water ingress from the ground.
- Walls: Clear cavity or solid masonry walls
offer better flood resilience than filled or part-filled cavity
Summary of water entry strategy
- Floors: As for the water exclusion
- Walls: As for the water exclusion strategy.
Note: to meet current standards high density internal insulation
can be used. Concrete blocks dry more quickly than Aircrete blocks.
Internal cement renders should be avoided as these can prevent
The floating house concept was developed by Factor Architecten
in Holland. The two-storey houses are each built upon a 70t
watertight concrete box which not only provides buoyancy in times
of flooding but also provides additional living space in the form
of a basement.
When flooding occurs, the homes can raise up to 15ft by floating
on the water, guided and kept in place by two concrete piles. The
floating house concept proves concrete's credentials of
watertightness and robustness, valuable assets for flood-prone