If you live in Australia, you would be aware of worsening
drought and super bushfires affecting our nation. This is due to several factors which include
the pressure on inland water supplies, the lack of rainfall, the drying of the
Australian bushland, global climate change and natural earth cycles such as El
Niño and La Niña to mention a few. The
resulting combination of all these factors is that we are getting drier and our
global mean temperature is gradually rising.
Source: 1 ABC News and BOM
This means that the foundations underlying many houses are
also getting drier. In Melbourne,
Victoria and many suburbs, house foundations rest on clay soils that
unfortunately shrink and swell according to the amount of moisture that is
available. During normal annual cycles
this doesn’t present too much of a problem as moisture loss doesn’t penetrate
too deep into the clays and regular cycles ensure the moisture content doesn’t
deviate too much, but because we are experiencing more abnormal drier
conditions for longer periods, the clay soils are beginning to loose their
constant levels of moisture, consequently drying more and moving more as a they
dry. Some clays surface movement can
move as much 75mm and can really wreak havoc with foundations if not properly
engineered to withstand such conditions.
Similarly, an inundation of rain can have a swelling affect. In many cases, engineers didn’t anticipate
the underlying moisture abnormality to effect shallow foundations to the extent
that we are beginning to see during a building’s expected lifetime, which the
design life is taken to be 50 years according to
AS2870-2011 Residential Slabs and Footings Standards. Buildings under normal climatic conditions
will generally produce minor cracking and slight movement that may affect a
door closure or window movement but will generally revert back to the original
position once a normal regular seasonal climatic change takes place, but during
abnormally drier conditions, extreme cracking can result internally and
externally and foundations become exposed to differential foundation
movement. As we continue to dry out and
as the global climatic conditions become hotter and water resources deplete,
the cracking and movement of shallow house foundations may become the new norm,
and expensive engineering solutions maybe required to permanently correct the
issue. When building or buying an
existing house, or potential site, a soil test included as part of the
conditions of sale, will confirm the soil type and profile which gives the
buyer incite and due diligence to make an informed decision, or prepare for
prevailing conditions. Our soil testingservice includes this information at no extra cost. So, if you need a soil test in Melbourne
suburbs down to the Mornington Peninsula, Philip Island or anywhere between,
give Chris a call 0400 372 763.
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