New City of Moreton Bay Secondary Dwelling Rules

This article has been updated from the original posted on 27th February 2023.

In October of 2024 the City of Morton Bay (CMB, the new name for the previously named Moreton Bay Regional Council) amended the town plan to remove loopholes and flaws in the rules about how secondary dwellings could be used and approved.

colin explains the new city of moreton bay secondary dwelling rules

The last change came about in December 2022 when the state government declared they would allow secondary dwellings to be rented by removing the word “household” from the definitions of what a “dwelling house”, “dual occupancy” and a “secondary dwelling was.

• This change did not remove the need for the house and the secondary dwelling to share facilities.
• Some owners of houses with secondary dwellings did not want to share facilities, and some neighbours complained so the CMB amended rules.
• For a full list of changes go to MBRC Planning Scheme 2016 version 7 updates – Secondary dwelling – City of Moreton Bay
• The changes emphasise the need to share facilities and access and addressed privacy and setback issues.
• The changes do not impact a secondary dwelling in a Rural or Rural Residential zone.
• The biggest impact of the changes is to increase the lot size needed before a 55m² secondary dwelling can be approved. Under 800 m² it is now 45 m², over 800 m² it is now 45 m².

Dual Occupancy Homes

The state government’s removal of the word “household” removed the requirement for the occupant/s of a dual occupancy or secondary dwelling to be related to or associated with the occupants of the other house. This change mainly affects secondary dwellings as it was a way of ensuring there was sharing of facilities (e.g. a laundry) as opposed to a flat or a dual occupancy where the occupants have sole use of all facilities.

Local governments have since amended their definitions to match the state governments changes. To prevent the inappropriate approval of “dual occupancy”, the “secondary dwelling” was defined as subordinate to another dwelling on the lot and a “dual occupancy” was defined as not being a secondary dwelling whilst retaining the two dwellings in one concept.

Two Dwellings, One Title

A “dual occupancy” or duplex may be two dwellings on a single lot (one title) or two dwellings on separate lots that share common property as is common with units.

Town plans are about use and density. Typically, the further away from a commercial centre, the lower the density. Any development which increases the number of houses or people is kept closer to the commercial centre by zoning the lots.

The City of Moreton Bay says: ‘Dual Occupancies are not appropriate in all residential zones and precincts. They are supported in the General residential zone – Next Generation precinct to allow for an overall increase in residential density.

‘However, Dual Occupancies are not suitable in a General residential zone – Urban precinct, as the residential density associated with this form of development is too low. Dual Occupancies are not appropriate in the Rural or Rural residential zones.’

What the above means is, that if it’s not zoned for it, it’s unlikely you will be able to get approval for it.

Dual Occupancy House Designs

If your lot is zoned for “dual occupancy” or you can gain development approval, this is what you need to know:

• “Dual occupancy” is normally two dwellings sharing a common wall.
• A “dual occupancy” above a “dual occupancy” is not a dual occupancy, it’s a flat and is not allowed unless zoned for flats. More than two dwellings are also a flat.
• You can have a “dual occupancy” over a garage (Fonzie flat) but this normally only works if you have front and rear access.
• “Dual occupancy” works best on a corner lot as it has more frontage for driveways and car parking.
• The reason dual occupancies are commonly side-by-side dwellings, not one above the other, is that it is much easier to fire separate side-by-side dwellings than it is to fire separate one dwelling above another. This is why the rules for units are more expensive to comply with.

How much do house plans cost?

The Grouping of Dwelling Types

“Dwelling house”, “secondary dwelling” and “dual occupancy” are grouped because they are Class 1 for the purposes of the National Construction Code and if it’s not one, it’s the other, and if it’s none of them it’s a unit (a flat) which is a Class 2.

• One house = “dwelling house”.
• Two houses with one being subordinate to the other = “dwelling house” and “secondary dwelling”.
• Two houses with one not being a secondary dwelling = “dual occupancy”.
• None of the above = unit = run away if that’s not what you want to pay for!

Retrofitting

A detached “secondary dwelling” can go behind a house if greater than 1.8 m and less than 10 m from the main house. A “secondary dwelling” can go under a dwelling if facilities are shared. If facilities are not shared then it becomes a unit which cannot be built either because the zoning doesn’t allow it or because compliance costs (fire separation, fire exits) make it untenable.

At least that was my understanding before the state government interfered.

Unintended consequences of the New Moreton Bay Council Secondary Dwelling Rules

The building industry, especially town planners, building certifiers, lawyers and designers are still trying to work out what the state government changes mean, and what the unintended consequences of messing with established definitions and removing the local government’s ability to assess dwelling house applications in many circumstances will be.

If the local government rules don’t apply then the next layer of rules below apply. The hierarchy of rules goes like this:

• Local government town plan overrules …
• the Queensland Development Code (QDC) which overrules …
• the National Construction Code (NCC).

So, if local government town planning rules don’t apply, then the rules in the QDC apply? Maybe?

The problem is the QDC is silent on many things because they are normally covered in the local government’s town plan. However, all regional authorities have rigorously thought out town plans which will continue to be enforced through a different process with the same outcome.

It’s the same people assessing the applications against the same rules with only the assessment trigger changing, so the outcome will be the same. There will be no investor bonanza. Yes you can rent out a secondary dwelling but the approval process has the same outcome.

Essentially the state government changes, although well intended, will have little affect other than to allow the rental of secondary dwellings in some local government areas.

What Now?

The City of Moreton Bay and probably other regional authorities have accepted the changes to dwelling definitions. 

The Least Worst Option

We live with the least worst option because that’s as good as we’re going to get, although it is worthwhile reviewing the least worst option from time to time. One should not get excited and think that there is a simple answer.

It has been said that to every complex problem there is a simple answer … and this is normally wrong, which is why we often live with the least-worst option.

What’s the difference between Dual Occupancy, a Duplex, a Secondary Dwelling and a Granny Flat?

A “dual occupancy” is also known as a duplex. A “secondary dwelling” is also known as a granny flat.

Questions for Colin, or comments? Leave them in the comment section below, we’ll reply soon.