Understanding R-Codes fundamental to subdividing in WA

Anyone contemplating a subdivision or property investment based on a block’s land size needs some understanding of the residential design codes (R-Codes) that apply in Western Australia.

Unfortunately, the Department of Planning, Lands and Heritage (DPLH) takes two volumes of more than 300 pages to explain R-Codes.

But without digesting those voluminous tomes of text and tables, there are some basics to understand that will pave the way towards a better understanding of R-Codes and their importance in shaping property investment decisions.

The Residential Design Codes of Western Australia (volume one and volume 2), control all forms of residential development in the state through the planning approval process and the building permit process.

The R-Codes are a state planning policy and in the case of a residential subdivision should be considered in conjunction with any relevant local government policies in the area the property is located.

If you’re buying property in Western Australia with the intention of subdividing, it’s critical that you’re aware of exactly what you will and won’t be able to do with that land prior to signing a contract of sale.

While these codes relate to Western Australia, the principle is applicable nationally.

First steps in subdividing

The first step when looking at a property with the idea of subdividing it is to consider the land size and associated residential density allowed in that area.

If you’re considering purchasing a lot and think it has subdivision potential, it may or may not have, depending on the density allowed for that location.

The R-Codes provide the basis for defining residential density and the density code for certain areas are determined under local planning schemes, which are generally developed by each local authority.

You might be familiar with a block of land being referred to as R20 or R40 and so on.

These are the density codes for a parcel of land and inform you as to the potential lot yield that’s possible for that lot. The R-Codes were originally developed to represent how many dwellings could fit on one hectare of land (10,000 square metres), however the minimum and average land areas for some densities have since been altered.

Generally, the lower the R-Code number, the lower the density allowable in that location.

As a quick reference, the general allowances for common zonings in Perth in terms of single or grouped dwelling under the R-Codes is as follows:

Further, multiple dwellings (i.e. apartments) can also potentially be built on land with an R-Code of R40 or greater, with the maximum plot ratio dependent on the R-Code. Generally, the higher the R-Code, the higher the plot ratio and more you can build on a site.

An important point to note is that the WA Planning Commission (WAPC) will consider applications to vary the minimum site area requirement by up to five per cent. For some lot sizes, this could add another potential dwelling to your site.

A good starting point when considering a lot’s subdivision potential is discussing your options with the local council and finding out if there are any variations to the R-Codes in that particular area. While applications go directly through the WAPC, they will refer applications to the local council for advice.

It’s also useful to keep abreast of any potential changes to zoning that might be occurring in the local area you’re looking at purchasing in.

The local planning schemes, which determine an area’s R-coding, are developed by each local authority in line with state planning policy and are supposed to be reviewed at least every five years.

While it’s advisable to be very cautious when making purchasing decisions based on what’s only a potential change to densities, it could also mean you’re one step ahead of the rest of the market and be able to secure yourself a solid investment.

Recent changes to WA’s R-Codes

In a bid to increase urban density to improve housing supply and limit urban sprawl, code amendments implemented in April 2024 provide plot ratios that are intended to make Perth more compact.

Since those changes (to Volume 1), R-Code compliant granny flats can now be built on residential lots of any size without planning approval if they meet relevant local area setback requirements and do not exceed 70 square metres.

Planning Minister John Carey’s office said there were incentives that could allow for more inner suburban housing.

“The site area concessions apply to the size of the lot required for each house and the new reductions may mean that if you had a lot that could previously be subdivided into two lots, the 35 per cent concession — instead of 33 per cent — may mean that it can now be subdivided into three lots,” his office said in a statement.

“This means the lot can accommodate three homes instead of two.”

The code changes were accompanied by a number of planning reforms, including an online lodgement and tracking system, a new significant development pathway for projects valued at $20 million or more in the Perth and Peel metropolitan areas or $5 million or more in regional areas, and reforms to the Development Assessment Panels.