A retaining wall is a structure created to support an excavated or filled embankment.
The Land Development Guidelines, Schedule 6.9 of the City Plan, provides the City of Gold Coast’s minimum standards for developments encompassing clearing, contaminated soils, filling, earth retaining structures, earthworks, topsoil and grassing.
Conditions of reconfiguration (subdivision) approval may further regulate the height of retaining walls and it is recommended that the original subdivision approval be investigated.
Although there is no legislation that prohibits the construction of retaining walls along a site boundary, the City recommends that:
- a minimum clearance of 600 millimetres be made between any retaining wall and a property boundary to avoid any problems or disputed costs associated with the retaining wall, and
- a fence should not be placed over a retaining wall.
A combined fence and retaining wall of a height exceeding two metres above natural ground level and located within a setback area (one metre, if located within a waterfront setback area) will require a Referral Agency Assessment application to the City and building approval from a Private Building Certifier.
Please refer to the Referral Agency Assessment application page for further information.
Retaining walls vary in cost, durability, strength, occupying space and vulnerability to various hazards.
How are retaining walls categorised?
Retaining walls can be categorised by material:
- concrete, concrete blocks, shotcrete
- brick or stone masonry
Or by type of construction such as:
- sleeper wall (timber or concrete)
- crib wall (timber or concrete)
- reinforced walls (concrete or shotcrete)
- weight walls (boulder or mass concrete or masonry).
What are the advantages and disadvantages of the different types of retaining walls?
- Timber walls are vulnerable to vermin infestation (white ants) and weathering.
- Dampness causes timber to rot significantly while it increases the strength of young concrete and lime mortar.
- Boulder retaining walls and crib walls occupy large spaces.
- The stability of a boulder retaining wall is highly dependent upon the skill of excavator operator in choosing the right boulder for the right location.
- Footings for reinforced concrete or reinforced concrete block retaining walls can be extended either in front or behind the wall. This can be extremely helpful in circumstances where space is limited in one direction such as retaining walls at property boundaries.
Seek advice from a Registered Professional Engineer of Queensland (RPEQ) to find the most suitable retaining wall for the conditions on your property.
Do I need to obtain a building approval for a retaining wall?
You do not need to obtain a building approval if the wall satisfies all three following conditions:
- the retaining wall has no surcharge loading (for example, a driveway above the retaining wall will impose a surcharge loading on the retaining wall)
- the retaining wall is not located within 1.5 metres of a building or another retaining wall
- the height of the retaining wall measured from the adjacent natural ground level is less than one metre.
If the retaining wall cannot satisfy all of the above conditions, it is considered an assessable development requiring a building approval.
What if I don’t obtain an approval for my retaining wall?
If you construct an assessable retaining wall without first obtaining a building approval you have committed an offence against the Building Act 1975. There are heavy penalties for offences against this legislation.
What are the correct steps to build a retaining wall?
You should take the following steps prior to building a retaining wall to avoid future problems:
- consult with an engineer, an architect, or a building designer to prepare a plan showing the location of the retaining wall on your property
- consider at least 600 millimetre clearance between the property boundary line and the closest part of the retaining wall
- ensure that the wall is not within 2 metres of Council underground services (sewer main, stormwater pipe or water supply main pipe)
- engage a Registered Professional Engineer of Queensland (RPEQ) to select, design and certify the most suitable type of retaining wall for the site
- advise the RPEQ if you are planning a another structure that may impose a surcharge loading on the wall (for example: driveway or building loads adjacent to wall)
- obtain a copy of the engineer-designed section for the wall signed and certified by the RPEQ
- obtain a building approval if a surcharge loading is imposed on the wall or the height of the wall is one (1) metre or greater, or the wall is located within 1.5 metres of a building or another retaining wall
- a building approval can be obtained from Council or from a suitably qualified private building certifier from council prior to construction of the wall
- engage a Registered Builder to build the wall under the supervision of the RPEQ
- obtain inspection certificates from the RPEQ for the construction of the wall at different stages (excavation, reinforcement, subsoil drainage and final)
- obtain a final certificate from the private building certifier.
Note: Items 7, 8 and 11 are not necessary where the retaining wall is self-assessable.
While every effort has been made to ensure the accuracy of this information, City accepts no responsibility for any error or omissions. However, the City would appreciate advice should any error be discovered.
To determine if you need approval for your earthworks, contact the Planning Enquiries Centre on 07 5582 8708 or refer to the City Plan.
To make a complaint to the City about an existing retaining wall, please refer to report a problem information and online form..