Does a Retaining Wall Need Council Approval in Ryde NSW?

Executed

A Ryde Site Assessment

Adam Murphy of ANS Design reviews retaining-wall exempt development and complying development CDC requirements in Ryde, NSW. — Adam Murphy of ANS Design examines whether a proposed retaining wall in Ryde could qualify as exempt development or complying development through a CDC.

By Adam Murphy, Principal Building Designer, ANS Design

Retaining walls can appear to be relatively simple landscaping structures. However, once a wall becomes higher, approaches a property boundary, or supports proposed excavation and filling, the planning, drainage and structural requirements can become considerably more involved.

ANS Design recently undertook a preliminary video review of a proposed masonry retaining wall at a residential property in Ryde. The owner’s name and exact property address have been withheld for privacy.

The project provides a useful example of why retaining-wall approval requirements should be checked before construction begins.

The proposed retaining-wall project

Based on the information and video supplied, the proposed work involves:

A residential property within the City of Ryde local government area
A masonry retaining wall of varying height
An estimated wall height ranging from approximately 300mm to 1,200mm
Sections potentially located as close as approximately 200mm to a property boundary
Retention of natural ground together with proposed excavation and filling
A sloping and irregular landscaped area
No known flooding, bushfire, heritage or easement constraints at this preliminary stage
No registered survey, detailed site plan or confirmed ground levels currently available

The video shows the proposed retaining-wall alignment through the rear and side landscaped areas. It also identifies changes in ground levels, boundary fencing, vegetation and existing drainage infrastructure, all of which must be accurately documented through a site inspection and a detailed survey prepared by a registered surveyor.

When can a retaining wall be exempt development in NSW?

Certain minor retaining walls and associated earthworks may be undertaken as exempt development under the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008.

To qualify, all relevant development standards must be satisfied. These include requirements that the work:

Does not involve cut or fill exceeding 600mm above or below the existing ground level
Is located at least 1m from every property boundary
Is not undertaken on a heritage item, flood-control lot or environmentally sensitive area
Is at least 40m from a natural waterbody
Does not redirect surface water, groundwater or sediment onto adjoining land
Has a retaining-wall height no greater than 600mm
Is separated from another retaining wall or structural support by at least 2m
Is at least 1m from any registered easement, sewer main or water main
Incorporates adequate drainage connected to the property’s existing stormwater system

These are cumulative standards. Meeting the maximum height requirement does not, by itself, make a retaining wall exempt development. The boundary setback, drainage, earthworks and land constraints must also comply.

The current requirements can be reviewed under clauses 2.29 and 2.30 of the NSW Exempt and Complying Development Codes SEPP.

Why the existing and proposed levels matter

A retaining wall cannot be properly assessed using only its visible face or nominal blockwork height.

The assessment must consider:

Existing natural ground level
Proposed finished ground level on both sides
Maximum excavation depth
Maximum fill depth
The level at the base of the wall
The wall’s uppermost structural point
Any footing, foundation or stepped construction
The cumulative effect of multiple walls or terraces

For this project, the absence of a registered survey means the height of the wall and the extent of cut and fill cannot yet be accurately verified.

A registered survey will identify the property boundaries, existing surface levels, dwelling position, fences, visible services, trees and other relevant site features. Proposed levels can then be documented against the existing levels.

Could the work require a Development Application?

Where a retaining wall does not qualify as exempt development, another approval pathway must be identified before work begins.

Because the proposed wall may:

Reach approximately 1,200mm in height
Be located close to a property boundary
Accommodate both excavation and filling
Require structural engineering
Potentially affect drainage close to adjoining land

a Development Application may be required.

A complying development pathway should not be assumed. Its availability depends on the precise nature of the work, the applicable code, the land constraints and confirmation from the certifier that the proposal constitutes permissible complying development.

City of Ryde advises that a CDC can only be issued where a proposal strictly complies with the applicable Codes SEPP provisions. Its lodgement requirements may include scaled architectural plans, a registered survey, engineering details, stormwater information, erosion controls and other supporting documents. Further information is available through City of Ryde’s complying-development guidance.

If a DA is necessary, the proposal will also need to be considered under the Ryde Local Environmental Plan and applicable parts of the Ryde Development Control Plan.

Based on the information presently available, the proposed retaining wall does not satisfy the relevant exempt-development standards or the requirements for approval through a Complying Development Certificate. In its current form, the proposal would require a Development Application, followed by a Construction Certificate before construction could commence.

The client therefore engaged Adam Murphy of ANS Design to redesign the retaining-wall layout. The revised design introduces battered landscaping and relocates sections of the retaining wall to satisfy the relevant exempt-development standards under the applicable State Environmental Planning Policy (SEPP).

Subject to confirmation by a registered surveyor, a detailed site inspection and verification of all applicable planning requirements, the redesigned proposal is intended to proceed as exempt development. This approach may save the client thousands of dollars by avoiding the additional application fees, consultant reports and approval documentation that could otherwise be required for a Development Application and Construction Certificate, or a Complying Development Certificate application.

City of Ryde considerations if a Development Application were sought

If a Development Application were sought, the City of Ryde’s landscaping guidance would reinforce the importance of retaining natural ground levels and minimising excavation and filling across the site.

As part of its assessment, Council may consider the proposed depth of excavation, amount of fill, retaining-wall heights, fill adjacent to side and rear boundaries, privacy impacts on neighbouring properties, overland-flow paths, stormwater disposal, and the protection of the site’s existing landform and natural features.

The City of Ryde’s published landscaping and associated-development information sheet identifies a general maximum retaining-wall height of 900 mm outside the dwelling footprint for residential landscaping assessed through a Development Application. As the proposed wall may reach approximately 1,200 mm, the design may require modification or a well-supported planning justification addressing the variation and its potential impacts.

This information is general guidance rather than a final site-specific determination. The applicable Ryde Local Environmental Plan, Development Control Plan and current Council policies would need to be checked when preparing the application.

Structural engineering will be important

A masonry retaining wall supports lateral soil pressure and may also be affected by:

Saturated soil
Surface-water runoff
Surcharge from nearby structures
Boundary fencing
Trees and roots
Sloping ground
Construction access
Movement of adjoining soil

For a wall approaching 1,200mm high and located close to a boundary, structural engineering should be expected.

The engineer may need to design and certify:

Footings
Reinforced masonry
Wall thickness
Reinforcement
Drainage aggregate
Waterproofing or tanking
Agricultural drainage lines
Wall capping
Construction joints
Any fence loads applied to the wall
Protection of the adjoining property during excavation

The exact wall system should not be selected solely for appearance. It must be suitable for the soil conditions, retained height, available footing width and proximity to the boundary.

Drainage is not optional

Water is one of the most common causes of retaining-wall movement and failure.

The retaining wall must not redirect water or sediment onto the neighbouring property. Its design will generally need to consider:

Subsoil drainage behind the wall
Free-draining aggregate
Geotextile fabric
Waterproofing
Surface falls
Collection of runoff
Connection to an approved stormwater disposal point
Protection against blockage
Sediment and erosion controls during construction

The video appears to show an existing surface inlet or drainage structure near part of the proposed wall alignment. Its purpose, invert level and connection will need to be confirmed before the wall and finished surface levels are designed.

Working close to the boundary

A wall approximately 200mm from a boundary requires particular care.

Before construction, the exact boundary must be established by a registered surveyor. Existing fences should not be relied upon as proof of the legal boundary position.

The design must also prevent:

Footings extending into the neighbouring property
Excavation undermining the boundary fence or adjoining land
Drainage discharging onto adjoining land
Damage to neighbouring structures
Unauthorised access to the adjoining property
An unreasonable increase in overlooking caused by raised ground levels

If construction access from the adjoining property is necessary, the owner or contractor must obtain the adjoining owner’s permission separately.

Information still required

The next stage should include obtaining:

A registered detail and level survey
A current planning certificate and title search
Deposited plan and easement information
Sydney Water sewer-service information
Confirmation of flooding, heritage and other land constraints
A scaled retaining-wall layout
Existing and proposed levels on both sides of every wall
Maximum cut, fill and retained heights
Structural engineering advice
A stormwater and subsoil-drainage solution
Written confirmation of the appropriate approval pathway

Preliminary conclusion

Based on the video and information currently available, the proposed masonry retaining wall should not be treated as exempt development.

The two clearest issues are:

Proposed wall heights potentially reaching approximately 1,200mm, exceeding the 600mm exempt-development limit
Sections located approximately 200mm from a property boundary, failing the minimum 1m exempt-development setback

The final approval pathway cannot be confirmed until a registered survey establishes the boundaries and existing ground levels. Once that information is available, the wall can be properly designed, assessed against the applicable planning controls and referred to a structural engineer.

Starting with accurate levels is likely to save considerable time and reduce the risk of redesign, neighbour disputes, drainage problems or unauthorised building work.

How ANS Design can assist

ANS Design can assist homeowners with:

Preliminary retaining-wall planning assessments
Site and survey coordination
Existing and proposed level plans
DA or CDC documentation, where the relevant pathway is available
Coordination with structural and stormwater engineers
Council and certifier enquiries
Residential alterations, additions and landscape-related structures

If you are considering a retaining wall in Ryde or elsewhere across Sydney, obtaining planning advice before excavation begins can help establish the correct approval pathway and documentation requirements.

This article provides general planning information only. Requirements vary depending on the property, land constraints, wall design and associated earthworks. Project-specific advice should be obtained before construction.

Contact ANS Design to discuss your residential building design project in NSW.

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