Do You Need Council Approval for a Retaining Wall in Perth?

Why the answer is "it depends"

Ask ten Perth homeowners whether a retaining wall needs council approval and you will hear ten different rules of thumb. Some of them were right for a different council, some were right years ago, and some were never right at all.

The real position in Western Australia comes from two separate systems working side by side:

1. Building control, under the Building Act 2011 and the Building Regulations 2012. This decides whether the wall needs a building permit, which is about whether it is structurally sound and safe, and how it affects neighbouring land.
2. Planning, under the local planning scheme for your area and state planning policy, including the Residential Design Codes. This decides whether the wall needs development approval, which is about things like height near boundaries, overlooking, streetscape and heritage.

A wall can need one, both or neither. Your local government administers both for most residential work, which is why the first call should almost always be to them.

Building permits: what councils say

Building permits in WA are issued by a permit authority, which for most homes is the local government. The Building Regulations set out which kinds of work need a permit and which are exempt.

Published guidance from Perth local governments gives a useful starting point. The City of Vincent lists a retaining wall over 500 mm in height among work that needs a building permit. The City of Fremantle's guidance describes a 0.5 m height in the context of walls associated with other building work or with protecting adjoining land, and says retaining walls should be designed by a practising structural engineer regardless of height.

What that means in practice:

• Walls retaining more than about 500 mm are likely to need a building permit in many Perth councils. Confirm with yours.
• Lower walls can still need a permit. If the wall protects a neighbour's land, sits on or close to the boundary, could affect a neighbouring building or changes how water drains, your council may treat it differently.
• Engineering is common. Several councils expect a structural engineer's design for retaining walls, and an engineer's drawing is usually needed with any permit application for a wall that carries a load.

Don't measure height from the top of the garden bed. Retained height is generally the difference in ground level from one side of the wall to the other. If you are unsure, ask the council or the builder to explain how they measure it.

Certified and uncertified applications

In WA, building permit applications can be lodged either with a certificate of design compliance from a registered building surveyor, or without one so that the local government does the assessment. The certified route can be quicker for some projects. Your builder or a private building surveyor can explain which suits your wall.

Planning approval: a separate question

A building permit only tells you the wall is built properly. It does not tell you the wall is allowed where you want it. That is the job of planning.

Planning questions most often come up when:

• The wall is on or close to a boundary. State planning rules for residential lots include provisions about fill and retaining near lot boundaries, which can mean setbacks or approval for higher walls.
• Ground levels are being raised. Filling behind a new wall can create overlooking into the neighbour's yard. Privacy and visual impact are planning issues.
• The wall is in the front setback. Front walls and fences are often covered by local planning policies about height and visual permeability.
• The property is heritage-listed or in a heritage area. Changes visible from the street, including front walls, may need approval and have design requirements.

Your local government's planning department can tell you whether your design needs development approval and what information to provide.

Boundaries, neighbours and fences

Most Perth retaining walls sit near a boundary, so the neighbour is almost always part of the story.

Building work that affects next door

The Building Act 2011 includes provisions dealing with building work that affects adjoining land, such as excavating near a neighbour's footing, needing access to their side, or a wall that will protect their land. Depending on the situation, this can require the neighbour's consent or an order before the work goes ahead. Your local government can explain how this works for your wall.

Who is responsible for the wall

There is no single answer that fits every case. A common starting point is that whoever changed the natural ground level, by cutting into it or filling it, is expected to retain it. But walls change hands, estates are built by developers, and fences get added later. If you and your neighbour disagree about who should pay to build or fix a boundary wall, get advice before work starts.

Dividing fences on top of walls

The Dividing Fences Act 1961 sets out how neighbours in WA share the cost of a dividing fence and how to give notice. A fence sitting on a retaining wall raises extra questions: how the fence height is measured, whether the wall is part of the fence, and who pays for the extra structure needed to carry it. These questions are best settled by agreement, in writing, before anything is built. The WA government publishes guidance on dividing fences, and local governments often have their own fencing local laws.

Practically, if a fence will sit on the wall:

1. Tell the builder at the quote stage so the wall is designed for the wind load
2. Agree with the neighbour on the fence type, height and cost sharing
3. Check with your council whether the combined height of wall and fence triggers any approval

Underground services and power lines

Before any digging, lodge a free enquiry with Before You Dig Australia to find out where underground cables and pipes run. Sewer and water mains, gas lines and telecommunications cables are common under Perth suburban blocks. If a wall is planned near a sewer or water main, the water utility may need to approve the work. Where overhead power lines cross the site, keep machinery well clear and talk to the network operator if work will come close.

Registered builders and insurance

Larger home building work in WA generally needs to be carried out by a registered building contractor, and some work needs home indemnity insurance. Whether that applies depends on the value and type of work. Ask the builder whether your job falls into that category and to show you their registration and insurance. We ask the contractors we work with to hold the registrations and insurance the job needs; you are entitled to see them before work starts.

A simple checklist before you build

• Measure roughly how much ground the wall will retain, at its highest point
• Note whether it sits on or near a boundary, and whether it will carry a fence, driveway, pool or building
• Call your local government's building and planning teams and describe the wall
• Ask whether a building permit, development approval, or both are needed
• Ask whether engineering drawings are required
• Talk to the neighbour and put any agreement in writing
• Lodge a Before You Dig enquiry
• Agree in writing who lodges the permit and when work can start

How we can help

When you request a quote through this site, the builder who visits can tell you whether they think your wall is likely to need approval and whether engineering will be needed. They can often arrange the design and lodge the application as part of the job. The final decision always rests with your local government, so confirm with them before work starts.

For budgeting, see the retaining wall cost guide. For wall types, start with limestone retaining walls or block and engineered walls. To arrange a site visit, call 08 7666 2963.