Rising damp in concrete footings and walls
is the wicking of water through concrete, and
evaporation into the building. This causes excessive
humidity and may lead to dampness and mold.
Rising damp does not produce pools of water (as can be the case
with waterproof failure of a concrete wall), but a constant
musty smell, growing insidiously stronger when concrete is
expose to more water.
An excellent example of wicking action
and rising damp is the flow of water in a Redwood tree:
The roots soak up water from the
ground, similar to the concrete footing;
The truck transfers the water
vertically, similar to the concrete wall above the
footing;
The leaves evaporate water to the
air; just as the interior concrete wall evaporates to
the interior.
Different Materials Show Varied Wicking
Effects
Material
Description
Height of Action
Gravel
Large spaces between rocks and
pebbles prevent wicking forces from acting on
water.
Zero
River Sand
Small, compacted sand particles
will induce small wicking forces on the water.
From 1/2' to 2' as per compaction
Clay
Small particle size creates
strong wicking forces.
