Common property vs lot property: the definitive guide
Note: This article is intended as a general guide only, and should not be taken as legal or professional advice. It’s essential to consult with a qualified professional or seek advice from your managing agent if you have specific questions or concerns about strata living.
This version of the article was updated on .
The one-minute guide
What the boundary is: Every strata property is divided into lots (individually owned) and common property (collectively owned by all owners via the Owners Corporation). The dividing line is defined in your strata plan.
Why it matters: Whoever owns an area is responsible for maintaining it and paying for repairs. Getting this wrong leads to disputes, unexpected costs, and insurance headaches.
The general rule: The lot boundary is typically the inner surface of floors, ceilings, and walls. Everything on the building's outer side of that surface is usually common property.
The grey areas: Balconies, pipes, windows, gardens, and structural elements are frequently misunderstood. This guide walks through each one.
Key tip: When in doubt, check your strata plan or ask your strata manager. The answer is always specific to your building.
One of the most common (and most costly) misunderstandings in strata living is not knowing who is responsible for what. When a pipe leaks, a window cracks, or a balcony needs resurfacing, the first question everyone asks is: whose problem is this? The answer depends entirely on whether the affected area is common property or lot property. This guide explains the distinction clearly, works through the most common grey areas, and tells you what to do when you are not sure.
Understanding the two categories
Every strata scheme in NSW divides its property into two categories. Understanding the difference is foundational to strata living.
Lot property
A lot is the individual unit, apartment, townhouse, or space that an owner purchases. Lot property includes everything within the lot boundary as defined in the strata plan. The lot owner is responsible for maintaining, repairing, and insuring their own lot property.
Common property
Common property is everything in the strata scheme that is not within a lot. It is collectively owned by all lot owners through the Owners Corporation (OC). The OC, managed by your strata manager, is responsible for maintaining, repairing, and insuring common property. The cost is shared across all owners through levies.
The legal definition
Under the Strata Schemes Management Act 2015 (NSW), common property is defined as any part of a parcel that is not comprised in a lot. The Strata Schemes Development Act 2015 (NSW) governs how lots and common property are defined in the strata plan itself. Your strata plan, registered with NSW Land Registry Services, is the authoritative document for your scheme.
| Audience | Relevance | Why it matters |
|---|---|---|
| Lot owners | Essential | Responsible for maintaining and insuring your own lot. Costs come from your own pocket, not levies. |
| Committee members | Critical | Must understand the boundary to correctly allocate maintenance responsibilities and approve spending. |
| Strata managers | Essential | Advise on maintenance responsibilities, interpret strata plans, and manage OC obligations. |
| Tenants | Helpful | Understanding what is and is not the landlord's or OC's responsibility avoids confusion during tenancies. |
| Prospective buyers | Very useful | Knowing what you will own and what you are responsible for is critical before purchasing. |
TL;DR: Your lot is what you own and maintain. Common property is what everyone owns together, via the OC.
Where exactly is the boundary?
The lot boundary is defined in the strata plan for your scheme. As a general rule under NSW strata legislation, the boundary runs along the inner surface (the inside face) of boundary structures, meaning floors, ceilings, and walls.
What this means in practice
For a standard residential apartment, the lot boundary sits at:
- Floors: the upper surface of the concrete slab or subfloor structure is common property. Floor coverings (tiles, timber, carpet) installed by an owner after registration are lot property. However, coverings that were there at the time of registration may be common property under NSW case law. The date of installation matters.
- Ceilings: the underside of the ceiling structure is common property. Internal ceiling linings and owner-installed fixtures within the lot are lot property.
- Walls: the inner surface of the boundary wall is the boundary. The wall structure itself is typically common property. Paint and wallpaper installed by an owner after registration are lot property, but paint applied at the time of registration may also be common property.
- External doors and windows: in most schemes, windows and external doors on the boundary of the building are common property because they sit in common property walls. However, doors and windows between one part of your lot and another part of the same lot (such as between your living area and a private balcony) are usually lot property. Always check your strata plan.
The registration date matters for surface fixtures
NSW courts have held that floor coverings (tiles, carpet, timber), ceiling linings, and paint that were present at the time a strata plan was registered form part of the 'upper surface of the floor' or 'inner surface of the wall' and may therefore be common property. Coverings installed by owners after registration are generally lot property. This distinction matters when water damage occurs or repairs are needed: who is responsible can depend on whether the surface covering was original or owner-installed. If in doubt, ask your strata manager to check when the scheme was registered and whether a common property memorandum has been adopted.
Important: your strata plan overrides the general rule
The above describes the default position under NSW law. However, your specific strata plan may define the lot boundary differently. For example, some plans include balconies within the lot, others do not. Always refer to your registered strata plan or ask your strata manager before assuming which category applies.
TL;DR: The lot boundary is usually the inner surface of floors, ceilings, and walls, but your strata plan is the definitive answer.
The definitive reference table
The following table sets out common areas and elements, and whether they are typically common property or lot property in NSW. Remember that your strata plan may differ. This is a guide, not a substitute for checking your own plan.
| Feature / area | Common property (OC responsibility) | Lot property (owner responsibility) |
|---|---|---|
| External walls | Entire wall structure and external face | Internal surface (paint, plaster, wallpaper) |
| Internal walls (within lot) | Walls shown as thick lines on the floor plan | Internal partition walls not shown as thick lines on the plan |
| Windows and frames | Windows in common property boundary walls (frame, glass, seals) | Window coverings (blinds, curtains); windows between parts of the same lot (e.g. living area to balcony) |
| External doors (to outside) | Doors on the building boundary to the outside world (usually) | Internal fittings and locks installed by the owner |
| Doors between lot and balcony/courtyard | Not applicable. These divide two parts of the same lot. | Entire door, frame, and fittings (usually lot property) |
| Internal lot doors | Not applicable | Entire door, frame, and fittings |
| Floors (structure) | Concrete slab or subfloor structure; floor coverings present at time of registration | Floor coverings installed by owners after registration (tiles, timber, carpet) |
| Ceilings (structure) | Ceiling structure; ceiling linings present at time of registration | Ceiling linings and fixtures installed by owners after registration |
| Balconies | Varies, check strata plan (often common property) | Balcony fittings if within lot boundary |
| Pipes and cables (shared services) | Pipes serving more than one lot | Pipes serving only your lot (within lot) |
| Hot water system (shared) | Entire system if serving multiple lots | System if exclusively serving your lot |
| Air conditioning (shared) | Shared plant, ductwork, risers | Individual unit if wholly within your lot |
| Gardens and landscaping | Common garden areas and planting | Courtyard or garden within a defined lot |
| Driveways and car parks | Common driveway; visitor parking | Designated car park space within your lot |
| Garage (attached) | Varies, check strata plan | Usually within lot if shown on plan |
| Storage cages | Common area structure surrounding cage | Contents and internal fittings of cage |
| Lifts and stairwells | Entire structure and mechanism | Not applicable |
| Roof | Entire roof structure | Not applicable |
| Common area lighting | Fittings and electrical circuits in common areas | Fittings within your lot |
| Swimming pool / gym | Entire facility and equipment | Not applicable |
| Letterboxes | Structure and mounting (often common property) | Individual box allocated to your lot |
TL;DR: When in doubt about any specific element, check your strata plan or ask your strata manager. This table reflects the typical position, not a universal rule.
The grey areas: common points of confusion
Certain areas generate disputes in strata schemes more than any others. Here is how each is typically treated under NSW strata law.
Balconies
Balconies are one of the most frequently misunderstood areas in strata. Whether a balcony is common property or lot property depends entirely on how it is defined in the strata plan for your scheme. There is no single rule that applies to all buildings.
- If the balcony is shown as part of the lot on the strata plan, it is lot property and the owner is responsible for its maintenance.
- If the balcony is shown as common property, the OC is responsible for structural repairs (such as waterproofing or the concrete membrane) while the owner may still be responsible for internal fittings.
- In many schemes, the balcony structure and waterproofing is common property while the tiles and fittings above the waterproofing membrane are the owner's responsibility.
This split responsibility is a common source of disputes. If your balcony leaks, the key question is whether the leak originates in the structure (common property) or a fitting within the lot. Your strata manager can help determine liability.
Pipes and water services
The general rule for pipes is:
- Pipes serving more than one lot (shared services) are common property, regardless of where they run, even if the pipe passes through your lot.
- Pipes serving only your lot are lot property if they are within your lot boundary.
This means that a leaking pipe running through your bathroom wall may be the OC's responsibility if it also services the apartment above or below you. The location of the pipe is not the determining factor. Who the pipe serves is.
Flexi hoses: a common lot property issue
Flexible braided hoses connecting taps, toilets, and appliances to water supply pipes are almost always within the lot boundary and are therefore the owner's responsibility. They are also a leading cause of water damage in apartments. For more on this risk, see our article: Why flexi hoses are a ticking time bomb in apartments.
Windows
In most NSW strata schemes, windows and their frames are common property because they form part of the external fabric of the building. This means the OC is generally responsible for repairing or replacing failed window seals, broken frames, or cracked glass, even though the window sits within the boundary of your lot.
However, window coverings (blinds, curtains, shutters) installed inside the lot are the owner's responsibility. And some schemes, particularly townhouses or low-rise developments, may define windows differently. Check your plan.
Internal walls and structural elements
Not all walls inside your lot are the same. Boundary walls shown as thick lines on the floor plan of the strata plan are common property. Internal partition walls between rooms within your own lot, not shown as thick lines, are generally lot property. Load-bearing columns and beams that pass through a lot are typically common property even if they sit within the lot boundary, because they form part of the structural fabric of the building.
This is important practically: owners cannot remove or modify common property structural elements (such as a load-bearing wall shown on the plan) without the OC's approval, and often a special resolution. But a non-structural internal partition wall within your own lot that is not shown as a thick line is generally yours to deal with, subject to any by-law requirements and council approvals.
Gardens and outdoor areas
Common garden areas maintained by the OC are clearly common property. The question becomes more complex for private courtyards, garden areas appurtenant to ground-floor lots, or areas enclosed by fencing but not defined in the lot on the strata plan. Again, the strata plan is the definitive guide. If an outdoor area is shown as part of your lot, it is your responsibility.
TL;DR: Balconies, pipes, and windows are the three most common sources of disputes. The strata plan, not location, determines responsibility.
A note on older schemes: the pre-1974 centreline rule
If your building was registered as a strata scheme before 1 July 1974, the rules described in this article may not apply in the same way. Older schemes were registered under different legislation that used a 'centreline rule' rather than the inner surface rule.
Under the centreline rule, the boundary between a lot and common property ran through the middle of the dividing wall, floor, or ceiling structure, rather than at its inner surface. This means that part of the dividing structure itself was lot property, and part was common property. The practical consequence is that maintenance obligations for walls, floors, and ceilings in pre-1974 schemes are often shared differently between the owner and the OC compared with newer schemes.
If your building predates 1 July 1974
Do not assume the standard inner surface rule applies. Contact your strata manager and ask them to confirm how the boundaries in your scheme are defined. For pre-1974 schemes, getting a formal legal opinion from a strata lawyer before undertaking any significant works near a boundary wall, floor, or ceiling is strongly recommended. The distinction can affect who is liable for repairs and whether you need OC approval to carry out works.
Who is responsible for what?
Knowing the boundary translates directly into understanding financial and maintenance responsibility.
The Owners Corporation's responsibilities (common property)
The OC must:
- Maintain, repair, and renew all common property in good condition.
- Keep common property clean, safe, and compliant with relevant laws.
- Insure common property buildings under a building insurance policy.
- Fund common property works from the administrative fund and capital works fund.
Costs are shared between all owners through levies. The OC cannot pass the cost of common property repairs onto an individual owner, unless that owner caused the damage through their own negligence or a breach of by-laws.
The lot owner's responsibilities
Each lot owner must:
- Maintain their lot in good repair and condition.
- Not let their lot fall into a state that causes damage to common property or another lot.
- Obtain approval before carrying out work that affects common property.
- Repair any damage they or their tenants cause to common property.
When an owner damages common property
If an owner (or their tenant, tradesperson, or guest) damages common property, the OC can require the owner to repair it or to pay for the OC's cost of repair. This can be pursued through the strata manager, and ultimately through NSW Civil and Administrative Tribunal (NCAT) if needed.
TL;DR: The OC repairs and maintains common property at the collective expense of all owners. Each lot owner is responsible for their own lot, and for any damage they cause to common property.
Maintenance and repairs: a practical guide
If something needs fixing in your lot
- Arrange and pay for the repair yourself using a suitably qualified tradesperson.
- If the issue may affect common property or another lot (e.g. a leak), notify your strata manager first.
- If you believe the root cause is in common property (e.g. a shared pipe), raise it with your strata manager in writing before undertaking any work.
If something needs fixing on common property
- Report it to your strata manager as soon as possible, ideally in writing or through the Netstrata app or portal.
- Do not arrange or pay for the repair yourself without OC authorisation. You are unlikely to be reimbursed and may void insurance.
- For urgent safety issues (e.g. a broken common area light, a burst shared pipe), your strata manager can authorise emergency repairs outside the normal process.
If you are not sure who is responsible
- Check your strata plan. Your strata manager can provide a copy.
- Ask your strata manager. This is one of the most common questions they handle.
- Do not delay reporting a potential issue while the question is being resolved. If a leak is involved, acting quickly reduces damage regardless of who ultimately bears the cost.
Using the Netstrata Owners Portal and app
Netstrata owners and residents can log maintenance requests, track repair progress, and access their scheme's financial records and documents, including the strata plan, through the Owners Portal and the Netstrata Space app. Logging issues in writing through the portal creates a clear record of when you reported something, which can be important if responsibility is disputed.
TL;DR: Report common property issues to your strata manager promptly and in writing. Handle lot property repairs yourself. When you are unsure, ask your strata manager before acting.
What happens when there is a dispute?
Disputes about maintenance responsibility are among the most common issues in strata. Here is how they are typically resolved.
Step 1: raise it with the strata manager
Your first step should always be to contact your strata manager in writing, setting out the issue clearly, what you believe the responsible party is, and what you are asking for. Strata managers deal with these questions routinely and can often resolve the matter quickly.
Step 2: committee decision
If the strata manager cannot resolve it directly, the matter may go to the strata committee. The committee has the authority to determine how common property is maintained and to approve expenditure.
Step 3: NSW Fair Trading mediation
If internal resolution fails, either party can apply for free mediation through NSW Fair Trading. Mediation is a required step before most NCAT applications and often resolves disputes without further escalation.
Step 4: NCAT application
If mediation does not resolve the matter, an application can be made to the NSW Civil and Administrative Tribunal (NCAT). NCAT can make binding orders requiring the OC to carry out repairs, or requiring an owner to reimburse the OC for repairs they were responsible for.
TL;DR: Start with your strata manager, escalate to the committee, then NSW Fair Trading mediation, then NCAT. Most disputes are resolved well before reaching the Tribunal.
Frequently asked questions
My neighbour's bathroom leaked into my apartment. Who pays?
This depends on the source of the leak. If the leak originated in a shared pipe (common property), the OC's insurance and/or funds should cover the damage to the building structure. If the leak came from a fitting within your neighbour's lot (such as a flexi hose or an overflowing bath), your neighbour is likely responsible for damage to their lot. Damage to your lot's contents would be covered by your own contents insurance. Contact your strata manager promptly and document everything with photographs.
Can I renovate my balcony?
If your balcony is common property (or even if only part of it is), you will need the OC's approval before carrying out any work. Depending on the nature of the work, this may require a special resolution at a general meeting, a by-law, or simply committee approval. Your strata manager can advise on what approvals are needed for your specific plans.
The OC is refusing to fix something I believe is common property. What can I do?
Put your request in writing to your strata manager, citing why you believe the area is common property. If the OC still refuses, you can apply to NSW Fair Trading for mediation, and if necessary, to NCAT for an order requiring the OC to carry out the work. NCAT has the power to make orders on maintenance obligations.
I want to install a garden shed in my private courtyard. Do I need approval?
If your courtyard is shown as part of your lot on the strata plan, installing a shed is generally within your rights, but you should check whether any by-laws restrict structures or external alterations, and whether the shed would affect common property (such as a shared fence or drainage). If the courtyard is common property that you have exclusive use of, you would need OC approval. Your strata manager can check the plan and relevant by-laws.
TL;DR: Most disputes and questions about responsibility can be resolved by checking your strata plan and asking your strata manager. When in doubt, always ask before acting.
Important
This article provides a general overview based on NSW strata legislation as at the date of publication. The standard inner surface boundary rule applies to schemes registered after 1 July 1974. Schemes registered before that date may be subject to the centreline rule, which produces different outcomes for maintenance responsibility. The specific boundaries and responsibilities in your scheme are defined by your registered strata plan and may differ from the general position described here. For advice specific to your scheme, always consult your strata manager or a qualified strata lawyer. Relevant legislation: Strata Schemes Management Act 2015 (NSW), Section 106 (duty to maintain common property); Strata Schemes Development Act 2015 (NSW), Section 6 (boundaries of lots).
Related reading
- Property management: maintenance and repairs — learning.netstrata.com.au
- By-laws in strata schemes: rules, creation and enforcement — learning.netstrata.com.au
- Insurance in strata schemes: coverage requirements and claims — learning.netstrata.com.au
- Disputes and resolution: conflict resolution processes — learning.netstrata.com.au
- Why flexi hoses are a ticking time bomb in apartments — learning.netstrata.com.au
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