1
Define the upstairs outcome
List the rooms, spaces and connections you want upstairs, and what must stay unchanged downstairs. Separate must-haves from nice-to-haves so proposals answer the same brief.
Second-storey extension planner
Plan the second-storey extension before comparing builder quotes
Define the upstairs outcome, understand the structural, approval and staging questions for your home, then compare itemised proposals against the same brief.
A request may be sent to up to three eligible suppliers, subject to service-area and supplier availability. Supplier availability and quote outcomes vary.
Local Coverage
Second-storey extension planning by city
Browse location pages for major Australian cities. Supplier coverage and availability vary by area.
Select your nearest city to compare local suppliers, suburb coverage and quote options.
Clear matching limits
How supplier matching works
Submit your project details once. We look for eligible local suppliers; availability and response times vary.
Up to 3
Supplier matches
Eligible suppliers are selected by service, area and current availability
Every one
ABN-checked suppliers
Suppliers are ABN-checked and manually reviewed before receiving leads
$0
Free for homeowners
No payment and no obligation to hire
No obligation
You decide
Compare any responses and choose whether to proceed
Free to request
Matching subject to supplier availability
No obligation to proceed
Before requesting proposals
Give every builder the same extension brief
Your brief defines the request; it does not establish structural capacity, approvals or design options. Builders and engineers still need to assess the home before confirming scope.
2
Document the existing home
Gather any plans, previous approvals and reports you hold, note the approximate age and construction of the home, and photograph the areas that would be affected.
3
Site, access and neighbours
Note block orientation, slopes, access for equipment, and neighbouring homes. Overshadowing, privacy and streetscape questions are assessed against the specific site.
4
Living arrangements
Decide whether you plan to live in the home during major structural work and discuss it during quoting, so staging, protection and site assumptions are comparable.
Property-specific checks
An extension quote is not an approval or a structural assessment
Approval, engineering, design-control, asbestos and contract questions belong in the brief before a start date is agreed.
Approval pathway for the exact address
Second-storey additions are assessed against the planning controls that apply to the property. The pathway and requirements depend on the site, the design and the jurisdiction - check before assuming.
Structural capacity needs engineering
Whether the existing footings, walls and structure can carry another storey is an engineering question specific to the building. No quote replaces a structural assessment.
Design controls
Height limits, setbacks, overlooking and character controls can shape what is possible. Ask who checks these against the property before design work is priced.
Asbestos-era materials
Homes built or renovated before 1990 may contain asbestos in walls, eaves and sheeting disturbed by structural work. Arrange an appropriate assessment before demolition begins.
Services and roof plumbing
Electrical, plumbing, drainage and roof water paths usually change with a new storey. Ask how services will be assessed, relocated and certified.
Contract and payment rules
Home building contracts, deposits and staged payments are regulated differently by state and territory. Check the rules for your jurisdiction before signing or paying.
Scope and delivery
Ask how the extension will actually be delivered
Two proposals for the same addition can describe very different projects. These questions surface the differences before you compare totals.
Who designs, who engineers
Ask who prepares the design and engineering, who coordinates approvals, and whether the builder prices from finished documents or expects design decisions along the way.
Weather protection and staging
Ask how the home is protected while the roof is opened, how long the exposed stages last in the proposed plan, and what happens when weather interrupts the sequence.
Staircase and ground-floor impact
A new staircase takes ground-floor space and changes circulation. Ask where it goes, what it displaces and what downstairs rework is included.
Selections and supply
Ask what you are expected to select and by when, what the builder supplies versus what you supply, and how selection changes are documented and priced.
Compare like with like
Make each extension proposal answer the same six questions
A total is only comparable when the structural scope, weather protection, allowances and payment terms behind it are visible.
1
Scope and referenced documents
The extension scope, the drawings and engineering the price is based on, and any assumptions that still need confirmation.
2
Structural works
Footing or structural strengthening, new structure, and the engineering documentation and inspections that certify it.
3
Weather protection and site management
Protection of the home and contents during roof-off stages, site amenities, waste management and working hours.
4
Approvals and compliance
Responsibility for approvals, certification and inspections, and which certificates you receive at completion.
5
Allowances
Every prime-cost item and provisional sum, the amount allowed, and the process when actual costs differ.
6
Payments, variations and defects
The payment schedule against stages, the written variation process, warranty responsibilities and how defects are handled.
Provider due diligence
Check the builder against the actual job
Marketplace eligibility is not proof of a builder licence, insurance policy or structural capability for your project. Verify the evidence that matters before hiring.
Identity and licensing
Confirm the contracting entity and ABN, then check the licence or registration requirements for structural building work in your state or territory.
Insurance evidence
Ask what insurance applies to the work, including any home building compensation or warranty insurance requirements in your jurisdiction, and request current evidence.
Relevant examples
Ask for comparable second-storey or structural extension projects, ideally with owners you can speak to.
Subcontracting and supervision
Ask who manages the site day to day, which trades are subcontracted and how structural work is supervised and inspected.
Written variations
Require scope, selection and price changes to be documented and agreed in writing before the work proceeds.
Completion and handover
Agree how completion is defined, what documentation is handed over, and how post-completion defects are reported and fixed.
How it works
Request supplier matches in three simple steps
Requesting supplier matches is free and does not obligate you to hire.
1
Tell Us What You Need
Share details about your second-storey extension needs using the request form.
2
Look for Supplier Matches
We look for up to 3 eligible extension builders based on service fit, coverage and current availability.
3
Compare Any Responses
Compare any responses you receive, including scope, price, timing and supplier terms. You decide whether to proceed.
Authority directory
Starting points, not a national rulebook
Each source has a stated role and limit. Use the council, code edition and licence register relevant to the property and proposed work.
NSW Government
Development assessment
A New South Wales explanation of how development applications are assessed and the pathways that apply to building work.
Limit: New South Wales only. Assessment pathways and exempt or complying development rules differ by state and territory.
Open source page (opens in a new tab)Australian Building Codes Board
NCC 2025 Volume Two
The National Construction Code volume covering houses, including structural and construction requirements relevant to additions.
Limit: A code baseline that is adopted with variations by states and territories and applied through professionals, not a homeowner design manual.
Open source page (opens in a new tab)NSW Government
Verify licence
The NSW portal for checking licence and registration information for building trades.
Limit: New South Wales only. Licence classes and registers differ in other states and territories; check the register for your jurisdiction.
Open source page (opens in a new tab)
Get up to 3 free second-storey extension quotes for your property
Requesting quotes is free for homeowners, and a request may be sent to up to three eligible suppliers, subject to service-area and supplier availability. Share the upstairs outcome, the existing home details and any known approval questions. Builders and engineers still need to assess the home before proposing a scope.
FAQ
Frequently Asked Questions
Clear answers to the questions homeowners usually ask before comparing quotes.
1 Do I need a structural assessment before adding a second storey?
Do I need a structural assessment before adding a second storey?
Yes, in practice. Whether the existing footings, walls and structure can carry another storey is an engineering question specific to the building, and it shapes design and price. Ask who performs the assessment, what it covers and how its findings feed into the proposal.
2 Is council approval required for a second-storey extension?
Is council approval required for a second-storey extension?
A second-storey addition is assessed against the planning controls that apply to the exact address, and the pathway differs by state, territory and site. Ask who is responsible for approvals in your proposal and confirm the pathway with the responsible council or a certifier.
3 What design controls can affect a second storey?
What design controls can affect a second storey?
Height limits, setbacks, overshadowing, privacy and character or heritage controls can all shape what is possible on a specific block. Ask who checks these against the property before detailed design work is priced.
4 Can I live at home during the build?
Can I live at home during the build?
That depends on the staging, how long the roof is opened, which services are interrupted and the safety controls on site. Discuss living arrangements during quoting so every proposal reflects the same assumption.
5 How is the home protected while the roof is open?
How is the home protected while the roof is open?
Ask each builder how the home and contents are protected during roof-off stages, how long those stages last in the proposed sequence, and what happens when weather interrupts the work. The answer belongs in the written proposal.
6 What does a new staircase mean for the ground floor?
What does a new staircase mean for the ground floor?
A staircase takes ground-floor space and changes circulation, and its location is one of the biggest layout decisions in an extension. Ask where it goes, what it displaces and what downstairs rework is included in the scope.
7 Could my home contain asbestos?
Could my home contain asbestos?
Homes built or renovated before 1990 may contain asbestos in walls, eaves and sheeting that structural work disturbs. Do not cut, drill or sand suspect material; arrange an appropriate assessment before demolition begins.
8 How does The Wombat extension request work?
How does The Wombat extension request work?
Requesting a supplier match is free for homeowners. A request may be sent to up to three eligible suppliers, subject to service-area and supplier availability. Supplier availability and quote outcomes vary, and you should independently verify the provider and written scope before hiring.
Expert resources
View all guides
Our Extension Guides
Free guides to help you plan, scope and compare a second-storey extension
Second Storey Extension Cost Guide 2026
How size, structure and site conditions drive extension pricing
Read guide
Second Storey vs Knockdown Rebuild
How to weigh extending upwards against rebuilding for your block
Read guide
How to Plan a Second Storey Addition
Step-by-step planning questions for an extension project
Read guide
10 Second Storey Mistakes to Avoid
Common planning and scoping errors to check before committing
Read guide Related services
Plan the whole project together
Compare related quotes for renovations, kitchens, bathrooms and roof work.
Home Renovation
Plan broader renovation work alongside the extension.
- Bundled scope planning
- Project coordination
- Builder quotes
Get Quotes
Kitchen Renovation
Coordinate kitchen changes with structural work.
- Cabinetry and benchtops
- Layout changes
- Trade coordination
Get Quotes
Bathroom Renovation
Plan new upstairs bathrooms as part of the extension scope.
- Waterproofing scope
- Fixture selection
- Compliance documentation
Get Quotes
Roof Restoration
Assess the roof separately where the structure stays single-storey.
- Condition assessment
- Material questions
- Separate scope
Get Quotes
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Planning a second storey?
Planning a second storey?
Get up to 3 free second-storey extension quotes, subject to supplier availability