Quick answer: Every granny flat in Victoria needs a building permit. A planning permit is typically not required for a unit of 60m² or less in most residential zones, provided conditions such as lot size, setbacks and overlays are met. An occupancy permit is required before anyone moves in. Browse our prefab granny flat designs or the owner builder option.
Planning permit vs building permit — what's the difference?
These two terms are often confused, and the confusion can cost homeowners weeks of unnecessary delays. They are two completely separate approvals, issued by different bodies, for different purposes.
A planning permit is issued by your local council. It assesses whether the proposed use of land and the siting of a structure is appropriate for the area — things like proximity to boundaries, neighbourhood character, and zoning rules. Not every granny flat project requires one.
A building permit is issued by a Registered Building Surveyor (RBS) — either private or council-appointed. It confirms that the proposed structure complies with the State Legislations (Building Act 1993, Building Regulations 2018), National Construction Code (NCC 2022) and relevant Australian Standards. Every granny flat project requires one, no exceptions.
The short version
Most Melbourne homeowners only need a building permit, not a planning permit. The building permit is what we facilitate for every project. If a planning permit is also required for your specific site, we identify this during your feasibility assessment.
Do I need a planning permit?
Under Victoria's Small Second Dwelling provisions, a granny flat (formally called a "Small Second Dwelling" or "Dependent Person's Unit" depending on the council) under 60m² typically does not require a planning permit in most residential zones — provided certain conditions are met.
You generally do NOT need a planning permit if:
- The unit is under 60m² total floor area
- Your property is in a General Residential Zone, Neighbourhood Residential Zone, or similar standard residential zone
- Your block is at least 300m² (requirements vary by council)
- The dwelling is on the same title as the primary residence
- Required setbacks from boundaries are maintained
- No restrictive overlays apply to your property
You may need a planning permit if:
- Your property has a Heritage Overlay (HO)
- Your property has a Vegetation Protection Overlay (VPO) or Significant Landscape Overlay (SLO)
- Your property is in a Special Building Overlay (SBO) — flood-prone areas
- The unit exceeds 60m²
- Your local council has specific secondary dwelling policies that differ from state provisions
Important
Overlay conditions are property-specific and are found on the Certificate of Title and through the Victoria Planning Provisions map. We check this for every project during your initial feasibility assessment — you don't need to research this yourself.
The building permit — what's involved
Regardless of whether a planning permit is required, every granny flat construction in Victoria requires a building permit before any work begins. Building without one is illegal and can result in significant fines, mandatory demolition orders, and complications when selling your property.
The building permit application requires a complete documentation package, which typically includes:
- Architectural plans (floor plan, elevations, sections)
- Structural engineering drawings and engineer's certificate
- Energy efficiency report confirming 7-star NatHERS rating
- Site plan showing setbacks, existing structures, and services
- Soil test report (used to determine foundation design)
- Property Information Certificate
- NCC 2022 compliance documentation
We coordinate all of these documents with independent licensed architects and structural engineers. Once the package is complete, it is submitted to the Registered Building Surveyor for review. Processing typically takes 2–4 weeks for standard residential projects.
The occupancy permit — the finish line
Once construction is complete, a final inspection is conducted by the RBS. If the structure meets all permit conditions, an Occupancy Permit (or Certificate of Final Inspection) is issued.
This document is critical. Without an occupancy permit:
- The dwelling cannot legally be occupied
- It cannot be rented out
- It may create complications when you sell the property
- Your home insurance may not cover a non-compliant structure
What we do
We coordinate all required inspections during construction (mandatory progress inspections are part of the building permit process) and manage the final inspection with the RBS to obtain your Occupancy Permit before handover.
Site variables that affect your project
Our prefab kit price is fixed — it covers the factory-manufactured modular components. However, several site-specific factors affect the total cost of your project and are quoted separately after a site assessment. Understanding these upfront helps you budget accurately.
| Component | Fixed or Variable | Why it varies |
|---|---|---|
| Prefab kit (walls, roof structure, internal fit-out) | Fixed | Factory-manufactured to a set specification per model |
| Foundation / slab | Variable | Depends on soil test results (M, H1, H2, E class soils require progressively more engineered footings), site slope, and excavation required |
| Roof and roof plumbing | Variable | Locally sourced and installed. Stormwater discharge distance to drain affects cost. Some sites require retention tanks |
| External wall cladding | Variable (upgrade) | Standard: fibre cement sheet, fit on site. Upgrade: James Hardie or equivalent premium cladding, locally sourced. Bushfire Prone Areas (BAL-12.5 and above) may require specific cladding specifications regardless of finish preference |
| Plumbing — hot & cold water | Variable | Distance from existing mains to the dwelling affects pipe run cost. Licensed plumber required |
| Roof plumbing — stormwater | Variable | Connection to existing stormwater system, or new connection depending on site layout |
| Mechanical plumbing (air conditioning) | Variable | System size, refrigerant line length, and condensate drainage vary by site |
| Electrical — connection, downlights, stove | Variable | Distance from switchboard, whether a new sub-board is required, and number of circuits. Licensed electrician required |
| Transport (regional areas) | Variable | Metro Melbourne delivery is standard. Regional Victoria incurs additional freight charges depending on distance and access conditions |
Overlays and special conditions
Overlays on a property title can significantly affect what is required — and in some cases, what is permitted. These are the most common overlays that affect granny flat projects in Victoria.
Bushfire Prone Areas (BAL ratings)
If your property is in a designated Bushfire Prone Area, the Bushfire Attack Level (BAL) assigned to your site will dictate construction requirements for external walls, windows, doors, roofing, and eaves. This is assessed by a qualified BAL assessor.
BAL ratings range from BAL-LOW (no additional requirements) through BAL-12.5, BAL-19, BAL-29, BAL-40, to BAL-FZ (Flame Zone). Most metropolitan Melbourne properties are BAL-LOW. Regional and outer suburban areas — particularly in the Dandenong Ranges, Mornington Peninsula hinterland, and outer east — are more likely to have higher BAL ratings.
BAL and cladding
At BAL-12.5 and above, standard fibre cement cladding may not be sufficient — specific fire-resistant cladding products (such as certain James Hardie systems) must be used, and the specification must be confirmed by a building surveyor. We identify this during feasibility and factor it into your quote.
Flood and Special Building Overlays (SBO)
Properties in flood-prone areas may require a planning permit regardless of size, and may have minimum floor level requirements. This is checked against the relevant council flood mapping during your site assessment.
Heritage Overlays (HO)
If your main house is in a Heritage Overlay, a granny flat in the backyard may still be permissible but the planning permit process will involve heritage considerations. This typically adds 4–8 weeks to the planning process.
The permit process — step by step
-
1
Site feasibility assessment We review your property details, check planning maps for overlays, confirm the applicable zone, and assess access and services. This tells us whether a planning permit is needed and what site-specific factors will affect your build.
-
2
Soil test A geotechnical soil test is conducted on your site to determine soil classification. This is used by the structural engineer to design appropriate footings for your site conditions.
-
3
Documentation package preparation Our independent architects and engineers prepare your full permit application — architectural drawings, structural engineering, energy report, site plan, and NCC compliance documentation.
-
4
Building permit application The complete package is submitted to your Registered Building Surveyor for assessment. Standard processing is 2–4 weeks. The RBS may request additional information or minor amendments.
-
5
Construction With your building permit issued, factory production begins. Concurrent groundworks on your site prepare the foundation and utility connections.
-
6
Mandatory inspections The building permit will specify mandatory inspection stages (footings, framing, wet areas). We schedule these with the RBS and ensure each stage is signed off before proceeding.
-
7
Occupancy permit After final inspection, the RBS issues the Occupancy Permit. The dwelling is now legally habitable and can be occupied or rented.
Frequently asked questions
Can I build without a permit and sort it out later?
No. Building without a permit ("unauthorised building work") is a serious legal issue in Victoria. Council has the power to issue a building notice requiring you to either obtain retrospective approval or demolish the structure. Retrospective approval is significantly more expensive and time-consuming than getting permits upfront — and is not guaranteed. It also creates issues when selling your property, as buyers' conveyancers will identify the unapproved structure.
How long does the whole permit process take?
For straightforward sites with no planning permit required, allow 2–4 weeks from initial assessment to building permit issue. If a planning permit is required, add 8–16 weeks depending on the council and any overlay conditions. We begin factory production as soon as the building permit is issued.
What if my neighbour builds without permits? Is that my problem?
Not directly — but if you're considering doing the same, be aware that councils do investigate complaints from neighbours and conduct proactive compliance checks. The risk is not worth it, particularly given that obtaining permits properly adds only weeks to a project and protects a significant asset.
Do I need to tell my mortgage lender?
You should check your mortgage terms. Most lenders require notification of any significant construction on the property. A properly permitted and occupancy-certified granny flat typically increases your property's value and can increase rental income — both of which are positive for lenders. An unpermitted structure is the opposite.
Can I rent out the granny flat?
Yes — once the Occupancy Permit is issued, the dwelling can be rented as a secondary dwelling on the same title. You do not need a separate title or development approval to rent it. It is treated as a residential tenancy under the Residential Tenancies Act 1997.