How much does a second storey extension cost in Melbourne? (2026)
Quick answer: A full second storey addition in Melbourne costs $200,000 to $380,000, more than a ground floor rear extension of the same footprint. The extra cost comes from structural engineering, temporary roof removal and a staircase eating into ground floor space, not just from building higher.
Second storey extension cost breakdown — Melbourne 2026
| Spec level | Price range | What is included |
|---|---|---|
| Basic | $200,000 – $270,000 | One bedroom plus bathroom over the existing footprint, standard finish, straightforward roof form, no major structural surprises. |
| Mid-spec | $260,000 – $330,000 | Two bedrooms plus an ensuite, quality finish throughout, a more considered staircase and landing layout. |
| Full-spec | $330,000 – $380,000+ | Multiple bedrooms and bathrooms, custom layout, premium finish, more complex roof lines or a footprint larger than the original ground floor. |
Prices for metropolitan Melbourne. Structural engineering, footing reinforcement where needed, and planning permits sit outside these ranges and are priced separately once a structural engineer has assessed the existing house.
What drives the cost of a second storey extension
The structural capacity of the existing footings
A single-storey home's footings were designed to carry a single storey. Adding a second level means an engineer has to confirm the existing footings can take the new load, or specify reinforcement where they can't. This assessment happens before a fixed-price quote is possible, not after, since it changes the number.
Temporary roof removal and weatherproofing
The existing roof comes off before the new level goes up, which means the house needs temporary weatherproofing for the period in between. How long that period runs, and how exposed the house is during it, depends on the roof's complexity and the weather window the build falls into. Melbourne's weather makes this a real scheduling factor, not a minor one.
The staircase and the space it costs you
A second storey needs a staircase, and a staircase takes real floor space on both levels, space a ground floor extension never has to account for. Getting the staircase placement right without eating into a room you actually want to keep usable is one of the more involved parts of the design, and it affects both levels' final layout.
Overshadowing and privacy assessment
Adding height changes what a home casts a shadow over and what it can see into next door. Most Melbourne councils assess this formally as part of the planning permit, which is why second storey planning permits generally take longer than ground floor ones. Inner-city councils can run 4 to 8 months for a complex application.
Is it cheaper to build up or build out?
On price alone, building out wins. A rear ground floor extension runs $150,000 to $280,000 against $200,000 to $380,000 for a full second storey covering a similar area, mostly because of the structural engineering a second level requires that a ground floor addition doesn't.
That doesn't mean building out is always the right call. A second storey makes more sense when the block genuinely doesn't have the room to extend at ground level, when a setback rule or heritage overlay limits what can be built out the back, or when keeping the existing garden and outdoor space actually matters more to the household than the extra cost of going up.
This is a decision worth making with real numbers for your specific block, not a rule of thumb. A site visit and a structural engineer's assessment of the existing footings will tell you which direction actually makes financial sense before you commit to a design.
Do the existing footings need to be reinforced?
Often, yes. Plenty of Melbourne homes built before the 1990s have footings that were only ever sized for the single storey sitting on them. A structural engineer's assessment is the only way to know for certain, and it happens before a fixed-price number is possible, not as a surprise partway through.
Where reinforcement is needed, that's real added cost, and it's worth knowing early. It sometimes changes the maths on the whole project, which is exactly why this assessment belongs at the start of the conversation, not somewhere in the middle of it.
Can you live in the house during the build?
Usually, yes, but a second storey addition disrupts the whole house in a way a ground floor rear extension doesn't. With a rear extension, a family can often keep living in the front rooms while the back of the house is a work site. With a second storey, the roof comes off, which means the whole house sits under temporary weatherproofing for part of the build, not just the room being added.
A written timeline should say exactly which weeks the roof is off and what the weatherproofing plan is for that period. That's not a detail to leave until it's already happening.
Planning permits, and where heritage overlays bite hardest
A second storey extension almost always needs a planning permit on top of the building permit, because adding height changes overshadowing and privacy for the neighbours. Most councils assess that formally, which is part of why second storey permits generally take longer than ground floor ones, 4 to 8 months isn't unusual for a complex inner-city application.
Heritage overlays add another layer, common across Footscray, Yarraville and plenty of the inner west's worker's cottages and period terraces. Many overlays specifically restrict what's visible above the existing roofline from the street, sometimes requiring the new level to be set back from the front of the house entirely. Check your property's overlay status with your council before a design is finalised, not after.
Ask what happens if the roof structure doesn't match the plan
Every period home in the inner west has surprises, and on a second storey job they usually show up the moment the old roof comes off. Non-standard stud spacing, roof framing that doesn't match the original drawing, timber that's not in the condition the plans assumed. Ask how the renovator prices for that before signing, not after the roof's already sitting under a tarp.
Worth knowing
If a structural engineer comes back and says the existing footings need significant reinforcement, it's worth getting that number before committing to a full second storey brief. Sometimes the reinforcement cost alone tips the maths back toward a ground floor rear extension instead, especially on a block that has the room for one. A second storey isn't automatically the right answer just because it adds more floor area, it's the right answer when the numbers for your specific block say so.
Common questions
How much does a second storey extension cost in Melbourne?
A full second storey addition in Melbourne costs $200,000 to $380,000, covering the structural frame, staircase, bedrooms, bathroom, roofing and internal finishes. That's more than a rear ground floor extension of a similar size, which runs $150,000 to $280,000, because a second storey adds structural load the existing footings weren't necessarily designed to carry.
Is it cheaper to build up or build out?
Building out is usually cheaper if the block has the room for it. A rear ground floor extension runs $150,000 to $280,000 against $200,000 to $380,000 for a full upper level, mostly because a second storey needs structural engineering the ground floor version doesn't. Building up makes more sense when the block is too small to extend out, or when a heritage overlay or setback rule limits what can be built at ground level.
Do existing footings need to be reinforced for a second storey addition?
Often, yes, especially on homes built before the 1990s where footings were only ever designed to carry a single storey. A structural engineer assesses this before a fixed-price quote is possible, and reinforcement work adds real cost before a single wall goes up. Get this checked early, it sometimes changes whether going up or out is the better call.
Can you live in the house while a second storey is being added?
Usually, yes, but expect more disruption than a ground floor rear extension. The roof comes off to build the new level, so the whole house is exposed to the weather for part of the build, not just the room being added. A written timeline should say exactly which weeks that happens, so you can plan around it.
How long does a second storey addition take in Melbourne?
A full second storey addition typically runs 12 to 16 months from signing to handover, the higher end of the 8-to-16-month range that applies to home extensions generally. Planning and building permits take longer than for a ground floor extension, since overshadowing and privacy impact on neighbours has to be assessed first.
Do you need a planning permit for a second storey extension in Melbourne?
Yes, almost always, plus a building permit from a registered building surveyor. Adding height affects overshadowing and privacy for neighbouring properties, which most councils assess as part of the planning process. Inner-city councils can take 4 to 8 months for a complex application, longer again if a heritage or neighbourhood character overlay applies.
What's the cost per square metre for a second storey addition?
Second storey additions in Melbourne run $3,000 to $5,500 per m2 of new floor area, the same range as a ground floor extension. Structural engineering, temporary roof works and the staircase aren't included in that per-m2 figure, they're priced separately and typically add $20,000 to $50,000 on top.
Does a heritage overlay affect a second storey extension?
It can, significantly. Many heritage overlays specifically restrict what's visible from the street, which includes anything built above the existing roofline. Some councils require the new level to be set back from the front of the house so it isn't visible from the footpath. Check your property's overlay status with your local council before finalising a design, not after.
Weighing up a second storey against a ground floor option? See the full home extension cost Melbourne breakdown, covering rear extensions, granny flats and garage conversions alongside the second storey figures here. See real completed extension work on our work page. Every gutted. quote follows a real site visit and comes with a written timeline before work starts, checked directly against a real BPC registration, never a phone estimate. Check your property's heritage overlay status with your local council or Consumer Affairs Victoria.