Heritage
Can I extend a house
in a heritage overlay?
Usually yes, at the rear. Heritage overlays are principally concerned with what the street sees, not what happens behind the building. Expect roughly 15% added to the build cost and several months added to approval — but a flat refusal is far rarer than people assume.
What an overlay actually controls
A heritage overlay does not freeze your house. It requires that changes be assessed against the contribution the building makes to a heritage precinct or its individual significance. In practice that assessment concentrates on the street elevation, the roof form visible from the footpath, and original fabric worth keeping.
What sits behind the building, out of public view, has considerably more latitude. This is why the standard inner-Melbourne solution — retain and restore the front rooms, build something contemporary at the back — is so common. It is not a compromise so much as the pathway the controls are designed to encourage.
What it costs
| Item | Why | Typical |
|---|---|---|
| Construction premium | Restoration work, matched materials, more careful demolition | +15% |
| Design iterations | More rounds before lodgement, sometimes a heritage consultant | $3k – $12k |
| Approval time | Heritage assessment sits on top of the standard planning path | +3 – 6 months |
Construction premium is an AE Index adjustment, applied in every estimate and shown as its own line.
Where it gets genuinely hard
Second storeys visible from the street
The hardest conversation in heritage. A first-floor addition set well back and concealed behind the existing roofline is often workable. One that reads from the footpath usually is not.
Removing original fabric
Verandahs, cast iron, original windows and chimneys on the street elevation are the elements assessments protect most firmly. Replacing them is a fight; restoring them is expected.
Demolition beyond the rear
Overlays generally permit demolition of later rear additions. Removing significant original structure is a different application with a much lower success rate.
Individually significant listings
Being individually significant rather than a contributory building inside a precinct raises the bar considerably. Check which applies to you — the difference is material.
What to do before you design anything
Get a planning property report for your address and find out three things: whether the overlay applies, whether your building is individually significant or contributory, and whether there is a council heritage citation for your street. Those three facts determine what is worth drawing.
Briefing an architect before you know them is how people end up paying twice for a design.
See what the overlay costs you
The estimator applies the heritage adjustment as a separate visible line, so you can see exactly what it adds.
Common questions
Does a heritage overlay stop me extending?
Rarely at the rear. Overlays assess changes against the heritage contribution of the building, and that assessment focuses on the street elevation and public views. Single-storey rear additions are usually achievable. Second storeys visible from the footpath are the difficult case.
How much does a heritage overlay add to renovation costs?
Around 15% on construction, plus design and consultant fees of roughly $3,000 to $12,000, plus three to six months of additional approval time. The time cost is usually more significant than the money.
What is the difference between individually significant and contributory?
A contributory building supports the character of a heritage precinct; an individually significant one is protected in its own right. The second carries a considerably higher bar for change. Your council heritage citation will say which applies.
Can I demolish the back of a heritage house?
Later rear additions are commonly approved for demolition, since they are not what the overlay is protecting. Removing original significant structure is a different and much harder application.
Related
When you are ready to build
AE Index is not a building company. When a project is ready to be priced properly, we pass it to a builder from our verified network — who will walk the site, inspect what is under the floor, and put a fixed price in writing. We are paid a fee by them on work that proceeds, and you are under no obligation to use them.
- Current domestic builder registration, confirmed with the Victorian Building Authority
- Domestic building insurance current and sighted
- Two completed projects contacted directly — not supplied testimonials
- Fixed-price contracts with a written variations policy
- Re-checked annually, and removed from the network on any lapse
Last updated 28 July 2026