GUIDE TO RETAINING WALLS
CONSTRUCTION, REPLACEMENT & MANAGEMENT
Retaining walls are one of the most underestimated structures
in residential developments and most common structures to
show signs of distress or collapse. Collapse can be sudden and
catastrophic due to soil mechanics. All retaining walls must satisfy
requirements of the Building Code of Australia (BCA) and Australian
Standards (AS). All retaining walls greater than 600mm in height
within 1m of a boundary and greater than 1m in height elsewhere
must be designed by a qualified engineer.
There are three categories of approval required
for the construction of retaining walls:
1. Exempt Development
Exempt developments do not require any approvals from
Wollongong Council (approvals vary between local governments).
Wollongong Council’s Local Environment Plan 2009 (LEP) outlines
the requirements to qualify as exempt development. Wollongong’s
LEP refers to the NSW State Environmental Planning Policy (Exempt
and Complying Development Codes) 2008.
Retaining walls cannot qualify as exempt if they are:
- Greater than 600mm high
- Within 1m of a boundary or form part of the boundary
- Within 2m of another retaining wall or structure
- Within 40m of a watercourse
Additionally, exempt development cannot be carried out on land
that is classified as:
- Flood affected
- Certain wilderness areas
- Certain heritage areas
2. Complying Development
Complying development is a fast-track approval process for
straightforward development proposals. Providing the proposal
meets specific criteria then either council or a private certifier
can approve the application under a complying development
certificate. During construction the certifier will undertake
regular inspections. Upon completion of construction, an
occupation certificate is issued by the certifier.
Retaining walls that satisfy the following may qualify as
complying development providing a number of other criteria
are met.
- Less than 1m from boundary and less than 1m high
- 1-1.5m from boundary and less than 2m high
- Greater than 1.5m from boundary and less than 3m high
3. Development Application
Development that does not fit into the categories above will
require the submission of a development application (DA)
to Wollongong Council. Once a DA is approved a principle
certifying authority (PCA) must be engaged. This can either
be a private certifier or a council certifier. Before construction
can commence the PCA must issue a construction certificate.
During construction the certifier will undertake regular
inspections. Upon completion of construction, an occupation
certificate is issued by the certifier.
Repair and Maintainance
Advice from local council is that if a significant portion of
wall is to be replaced then it constitutes new development.
If maintenance work is undertaken, then records and photos
should be kept in case of complaint from neighbours or
investigation by council. Walls that are located on boundaries
are considered more critical than walls inside the plot.
The above is a summary for information purposes only,
and does not cover the approval process in its entirety.
Professional engineering advice should be sought on a
case by case basis prior to proceeding with any work.
CONTACT OUR OFFICE FOR FURTHER ADVICE
