GUIDE TO RETAINING WALLS

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