Reference Documents - MCU23 0070

Home owners guide to planning
landscaping and maintenance
of foundations
Structural damage can result from        - under normal conditions. The
movement in clay soils caused by         performance of footings under this
varying moisture conditions around the   standard requires normal conditions to
perimeter of homes.                      be maintained around the house.
The majority of Queensland homes         This guideline identifies abnormal
are situated on what are termed          conditions that should be avoided
reactive clay soils. These soils are     and/or corrected.
subject to expansion and contraction     Dry seasons cause soils to dry out
depending on seasonal weather and        rapidly. Wet seasons cause soils to
site conditions. Sandy sites and rocky   become wet quickly. This results in
terrain are usually not prone to this    sudden extreme volume changes and
expansion and contraction.               movement in soil.
In Queensland, engineers design          Abnormal conditions (other than
footings to the Australian Standard      seasonal changes), may include the
AS2870 – 2011 Residential slabs          effect of trees, poor surface drainage
and footings. Footings correctly         and/or leaking plumbing. If not allowed
designed to this standard are intended   for in the engineer’s design, these
to accommodate the expected              types of abnormal conditions may lead
movements caused by seasonal             to movement and damage varying
volume changes in the soil (swelling     from minor to extreme.
when wet and shrinking when dry)



  NORMAL MOVEMENT EXPECTATIONS FOR BUILDINGS CONSTUCTED
  ON REACTIVE CLAY SOILS