Civil Engineering Reference
In-Depth Information
Other aspects of strawbale
building
manner, instead of cement renders and
plasters, traditional lime and/or natural
clay renders and plasters are used. Most
strawbale houses, of whatever type of
construction, are plastered inside and
rendered outside, so that when finished
they can look very similar to a traditional-
style cottage, very beautiful and with deep
walls - it is hard to tell that they are made
of straw. The walls need to be protected
from the weather using either several coats
of limewash, reapplied, as with all painted
houses, every few years, or an active silicate
paint, which is a mineral-based paint that
bonds with the quartz in the render, remains
vapour-permeable, and needs reapplying
only every fifteen years.
Straw is a very different material from
others we have become used to working
with in the twentieth century, such as
cement or timber. As we have seen, it is
natural, breathable, flexible, non-toxic, low
in embodied energy, safe and fun to work
with. Once it has finished its usable life as a
building material it will go back to the Earth
as part of the natural cycle of nature without
creating any waste, damage or pollution.
So in designing with straw it is sensible
to use other natural materials as well, as
like goes with like. Therefore you will find
roofs and floors insulated with sheepswool,
hemp or recycled paper, solid floors made
of limecrete and insulated with recycled
glass or blown clay, and roofs covered with
cedar shingles or planted with sedum. Once
you start thinking about a natural system
of building instead of an unnatural one you
begin to see how possible it all is.
Durability
Because of the simplicity of strawbale building,
it is possible to build a wide range of quality
structures, from a strawbale shed that might
only last ten years to a strawbale house to
last several generations. We can design to a
standard of 200 years minimum - anything
less is not sustainable, either environmentally
or financially. In the UK and Ireland, the oldest
buildings are fifteen years old, and some of
the early ones were never intended to be
more than experiments. However, there are
now two-storey semi-detached loadbearing
homes for social housing, classrooms and
whole schools, retail spaces, centres for com-
munity groups and new extensions to existing
houses, as well as hundreds of owner-built
houses, offices, studios and garages, animal
shelters, food and machinery storage barns,
and so on, all of which are expected to have a
usable life of more than 100 years. In the USA,
where it all began, there are about a dozen
When installing other aspects of the building,
such as the services, plumbing and electrics,
or the roof covering, these are done in much
the same way as you would expect in a
conventional house, but with thought given to
the way the building needs to breathe and be
flexible, minimising the environmental impact
of manufactured materials.
Strawbale building has become much more
than simply building a house with straw walls.
It is now leading the way in providing an
affordable solution to the need for thermally
efficient housing, with very low embodied
energy, using natural materials. Therefore it
is common to design foundations without
using cement or deep trenches. In the same
