What Can I Build on My RZ1 Block? Design Options Under MPA04

Since MPA04 commenced on 1 July 2026, a Canberra RZ1 block can now support far more than a single detached home. You can build a duplex (dual occupancy), two to three townhouses or terraces with a block subdivision, or a main dwelling plus a secondary dwelling, all up to two storeys plus attic, and all subject to canopy cover, site coverage, height and setback rules. The point of MPA04 is not to force you to build more. It is to give you the option. What is possible on your block depends on the block's size, shape, orientation and any heritage or environmental overlays sitting over it. This guide walks through the design options in plain English, with worked examples on typical RZ1 blocks in Kaleen, Curtin, Wanniassa and Ngunnawal.

I have been building in the ACT for 19 years and running Rentoule Projects for the last 5. In the six weeks since MPA04 commenced, the type of enquiry landing in my inbox has changed. It used to be "can I extend this or knock it down?". Now it's "can I turn this into two homes?" or "if I subdivided, what could I actually build?". The Pattern Book of pre-approved designs is still being developed, so for now, working out what a block can support is a case-by-case exercise between the owner, the designer, and the builder. This is my plain-English version of that conversation.

The RZ1 rules changed. Here's what actually changed

Before 1 July 2026, RZ1 blocks were almost exclusively single-dwelling territory. You could build one detached home. A secondary dwelling (granny flat) was possible in some cases but capped at 90 square metres of floor area and often gated by a minimum block size. Subdivision was rare. Anything beyond a single home on an RZ1 block usually required a separate rezoning application or a specific ACT Government exception, both of which took years and were rarely granted.

Under MPA04, the same RZ1 zone now allows:

• Up to two storeys plus attic on any RZ1 block
• Multiple dwellings on the one block (dual occupancy, and in some cases multi-unit)
• Block subdivision to create separate titles for each dwelling
• Block consolidation to combine two adjacent blocks into a larger site with a bigger design envelope
• A secondary dwelling with no fixed floor-area cap and no minimum block size for eligibility
• Terraces and townhouses in a form that used to be reserved for RZ2 blocks

The controls that came in alongside the freedoms are what shape the design. Canopy cover has to be at least 20 per cent of the block (up from 15 per cent). Site coverage stays at a maximum of 45 per cent. Boundary setbacks, driveway rules and private open space requirements apply per dwelling. If you missed the full explainer, the Missing Middle MPA04 article covers the regulatory detail and the Lease Variation Charge 50 per cent reduction (gazetted 29 to 30 June 2026, expires 31 December 2030 subject to certificate of occupancy). This article stays on the design side.

The six design options MPA04 opens up on an RZ1 block

1. The duplex (dual occupancy)

Two attached dwellings, side by side, on the one block. Each has its own front door, its own private open space and its own driveway. This is the most straightforward option and the one most owners I talk to are asking about first. Under MPA04 you can build this on any RZ1 block that meets the setback, canopy and site coverage rules. You can either keep the block on a single title (each dwelling shares the underlying lease and is sold under a Unit Title or Community Title arrangement), or subdivide to create two separate torrens-style titles. Two storeys plus attic is permitted, though many owners prefer single storey to keep the roof line low against the streetscape.

2. The townhouse row (subdivided)

Two to three individual homes arranged in a row, each on its own subdivided title. Typically two storeys plus attic. Each dwelling is a complete home with a private courtyard, its own laundry, its own garage or car space, and a separate street address. This is the option that changes the character of a block the most. It also delivers the most value in terms of separate saleable titles. Not every block can accommodate a row of three, so this option is very block-dependent. Block frontage, driveway configuration and canopy cover are usually the deciding factors.

3. Terrace houses (unified boundary)

Similar to townhouses but built as one continuous structure with shared party walls, and typically finished with a coherent facade running the full length of the block. Terraces read as a single architectural gesture from the street even though there are multiple separate homes inside. This is a design-forward option and the one that produces the best streetscape outcomes in the right setting. Better suited to blocks with strong street presence and inner-suburb style, but nothing in the MPA04 rules restricts terraces to specific suburbs.

4. Main dwelling plus secondary dwelling

A single main home plus a granny flat, both on the same block, both on the same title. The secondary dwelling is now uncapped in floor area (previously 90 square metres). This is the option most owners approaching retirement or with adult children are asking about. It keeps the main home as the primary residence and adds a self-contained smaller home for a family member, a rental, or a home office with sleeping quarters. You do not have to subdivide and you do not have to rent it out.

5. Multi-unit (up to three dwellings, two storeys plus attic)

Three separate homes on the one block, arranged either in a small townhouse row or with a rear laneway-style detached dwelling. This is a step up in complexity from the duplex and works best on wider or deeper RZ1 blocks (typically 750 square metres and up, but block shape matters more than area). The design has to earn its site coverage carefully, and canopy cover often becomes the binding constraint. Ainslie, O'Connor, Yarralumla and Curtin blocks with generous frontages are the ones most likely to support this.

6. Consolidated blocks (two RZ1 blocks combined)

If your neighbour is also considering redevelopment, MPA04 permits block consolidation. Combining two adjacent RZ1 blocks into a single larger site opens up better design options, longer street frontages, and often a more efficient use of setbacks. Consolidation is a lease variation exercise administered by the ACT Government, and it works well where two owners can agree on a coordinated project. It is not common yet but I expect it will be over the next few years, particularly on the edges of established suburbs where two families are both thinking about their next move.

Worked examples on real Canberra RZ1 blocks

Every block is different but the underlying maths is usually similar. Here is how I would sit down with an owner and work through what each of four typical RZ1 blocks could support.

Kaleen: 700 square metre block, established Belconnen suburb

A standard Kaleen RZ1 block on a quiet residential street. 700 square metres, roughly 20 metre frontage. Existing house is a 1980s three-bedroom brick veneer with a large backyard and mature trees.

What is realistically feasible: A duplex (two dwellings side by side) is comfortable on this block. Two storeys plus attic means each dwelling can hit around 200 square metres of floor area with private open space and a single garage each. Canopy cover at 20 per cent means keeping one or two of the existing mature trees and adding new plantings. A townhouse row of three is possible but tighter. The 20 metre frontage supports two driveways comfortably, three would require a shared driveway or laneway access which changes the design. Secondary dwelling behind the existing house is a lighter-touch option worth considering.

Curtin: 800 square metre block, established Woden suburb

Larger inner-south block with mature planting, corner or near-corner position common in Curtin. Existing house typically a 1960s or 1970s single-storey brick.

What is realistically feasible: A duplex is easy. A townhouse row of three fits well if the block is close to a corner or has generous frontage. A terrace design of three is stylistically well-suited to Curtin's streetscape. If the block is corner-lot, dual street access opens up an additional design option: two separate torrens-style dwellings each with its own street frontage, effectively subdivided along the corner axis. Owners in Curtin thinking about downsizing and monetising the block often lean toward two well-designed homes rather than three units, because the delivered outcome tends to sell better in that market.

Wanniassa: 750 square metre block, Tuggeranong

Standard Wanniassa RZ1 block, typically 1980s house on a suburban street with a walkable school and shops. Slightly further from town, so buyer demand is different from the inner suburbs.

What is realistically feasible: Duplex works well and often delivers the best return per dollar spent in this market. Main dwelling plus secondary dwelling is popular in Wanniassa because it lets an owner stay in the main home and add a modest rental or family suite without going through subdivision. Three-townhouse subdivision is possible but the local market for three individual titles at Wanniassa price points does not always support the construction cost. Consolidation with a neighbour is worth exploring if the neighbour is also considering their move.

Ngunnawal: 600 square metre block, Gungahlin

Smaller, newer block typical of Gungahlin. Existing house is often a 2000s brick-and-render four-bedroom. Blocks tend to be narrower than the older suburbs.

What is realistically feasible: Duplex is achievable but tight, and the 20 per cent canopy cover requirement pinches on a smaller block. Secondary dwelling is often the more elegant answer here because it uses the existing setbacks without triggering a whole redesign. Three-unit multi-dwelling on a 600 square metre Ngunnawal block is not realistic. If a Gungahlin owner wants to explore multi-unit properly, block consolidation with an adjacent owner is the pathway to look at.

The design rules that constrain the options

Every option above is subject to the same set of design controls. These are the ones that show up on almost every MPA04 project we scope:

• Canopy cover: 20 per cent minimum. Up from 15 per cent. This is often the binding constraint on smaller blocks and the reason a design that looks like it should fit on paper suddenly needs a rework.
• Site coverage: 45 per cent maximum. Unchanged. This is the maximum building footprint as a percentage of block area.
• Height: 2 storeys plus attic on RZ1. RZ2 goes to 3 storeys plus attic. Attic in this context means habitable space within a roof form, not a separate storey.
• Boundary setbacks and private open space per dwelling. Both are set by the Territory Plan and the Missing Middle Housing Design Guide (NI2026-312, effective 30 June 2026).
• Driveway and parking rules. Each dwelling generally needs its own car space, though shared driveways are permitted for multi-unit designs.

The Missing Middle Housing Design Guide is the reference document sitting behind all of this. It is worth downloading if you are getting serious about a design.

What about the Pattern Book?

The ACT Government announced a Canberra House Pattern Book of pre-approved missing middle designs as part of the MPA04 package. The idea is that a homeowner can pick a pre-approved design and get through the approval process substantially faster than a full custom design. As at the time of writing (August 2026), the Pattern Book is still being developed. No pre-approved designs have been released yet.

For now, that means every MPA04 project is a custom design exercise. Some owners are waiting for the Pattern Book to release before starting. Others are pushing ahead with custom designs on the basis that a well-designed custom home tends to sell for more than a pattern-book design, and the Pattern Book release timeline is uncertain. Both approaches are defensible.

Where the LVC 50 per cent reduction applies

The Lease Variation Charge is the fee paid to the ACT Government when a lease is varied to allow additional dwellings or subdivision. It is often the biggest single tax on a Missing Middle project. Under the reforms, eligible projects get a 50 per cent reduction (see the Missing Middle explainer for the four eligibility conditions). This is a time-limited concession. The certificate of occupancy has to be issued by 31 December 2030 to qualify. If your project is not going to be habitable by then, the full LVC applies. That is the single biggest reason not to sit on a project idea indefinitely.

How I sit down with a client thinking about MPA04

The first conversation is usually 45 minutes and covers three questions. What is the block? What outcome does the client want (income, family accommodation, downsize, sell to fund retirement)? What is the timeline? From those three answers I can usually tell the client which two or three of the six design options above are worth working up into a concept, and which ones to rule out. A designer comes in after that. Concept drawings and a pre-application planning check usually happen before any commitment to build. If you want to see how the whole feasibility-to-handover sequence runs, our renovate, extend, rebuild or move guide walks through the decision framework, and our dual occupancy service page covers the specifics of the dual occupancy pathway.

Talk to a builder before you talk to anyone else

If you own an RZ1 block in Canberra and you are wondering what MPA04 actually lets you do with it, get in touch. Coffee's on me. I would rather sit down with you for half an hour to work out which two or three design options are realistic on your specific block than watch you spend three months on a designer's concept that a builder is going to tell you cannot be delivered at your budget. If you would like to read the full regulatory explainer first, our Missing Middle MPA04 guide covers the rules, the Lease Variation Charge and the timeline in detail, and our dual occupancy service page walks through what a dual occupancy build looks like end to end.