Civil Engineering Reference
In-Depth Information
Causes of damp in buildings
and their solutions
there are many misconceptions about
foundations that are partly caused by the
rise in popularity of cement and concrete.
In
some building colleges, students are taught
that buildings can only have foundations
made of concrete, despite the evidence to
the contrary that surrounds us. Throughout
learning about strawbale building, you will
be encouraged to look at what's around
you, to keep things as simple and straight-
forward as they can be. There is no need
to overcomplicate anything, only to
under-
stand what it is that we want to achieve
and make choices based on the different
ways that it is possible to do so
.
Damp problems in any building, straw or
otherwise, are caused by poor design, lack
of maintenance, and inappropriate use of
materials
. They are slow to show them-
selves, sometimes taking 20 or 30 years,
which is why it can be hard to understand
why some of our buildings have become
very damp, because cause and effect are not
so obvious. But very few buildings in the UK
and Ireland actually suffer from rising damp,
contrary to popular belief. Damp is almost
always caused by something else instead.
We use foundations to achieve a stable base
that distributes the weight of whatever is
built upon it over the ground beneath, to
be sure that there is no unequal settlement
throughout the building, to allow flexibility
for the building to move over long periods
of time as the ground itself moves, and to
keep the inside of the building dry. In the
past, natural materials were used to protect
buildings; nowadays, manufactured ones
are used, and they do not perform in the
same way. So we also need to know the
essential properties of materials in order to
use them wisely.
Whatever a wall is made from, it can be
divided into three main areas that need atten-
tion: the base, because of contact with the
wet earth or from splashback as rain bounces
off the ground on to the walls; the top, owing
to rain running off the roof; and the face of
the walls themselves, in driving rain.
Contrary to popular belief, very few buildings
in the UK and Ireland actually suffer from rising
damp. Damp is almost always caused by some-
thing else instead.
It is necessary to discuss the causes of
damp in buildings because there are so
many misconceptions, about rising damp in
particular. If we can understand the causes
then we are more equipped to design well
and prevent it happening. This applies to
all buildings, not just straw ones, and the
principles discussed below can be applied
universally.
Poor design includes factors such as poor
detailing between two different roof pitches,
so that rain running off one is not prevented
from running into the wall of another;
or inadequate rain protection in severe
weather.
Common causes of damp due to lack of
maintenance include:
•
damage to roofs
