Common Property vs Lot Property (Australia-wide)
One of the most common and most disputed questions in Australia-wide strata schemes is whether a repair or maintenance issue falls under common property or lot property.
This distinction controls:
- Who must pay
- Who must arrange the repair
- Who carries legal liability
- Who must claim on insurance
- Who is responsible if someone is injured
Disputes over property responsibility are one of the leading causes of NCAT applications, insurance disputes, and owner conflict, especially in self-managed schemes.
This guide explains:
- What common property and lot property actually mean
- How boundaries are determined
- Who pays for what
- Where most disputes arise
- How these disputes turn into tribunal cases
- When professional review becomes essential
1. What Is “Common Property” in Australia-wide
Common property generally includes all areas of the building or land that are not part of an individual lot and are intended for shared use, building functionality, or structural support. It forms the physical backbone of the strata scheme and must be maintained by the owners corporation.
Common property commonly includes:
Roofs and external walls
This covers all outer surfaces, roofing materials, guttering, waterproofing membranes, and cladding. These elements protect the building and are almost always common property.Structural slabs, columns, and beams
Anything forming the structural framework of the building—including concrete slabs between floors—remains common property regardless of where they sit in relation to a lot.Stairwells, corridors, foyers, and lifts
All internal accessways used by multiple occupants fall under common property. This includes floor coverings, balustrades, lighting, and lift cars/mechanisms.Driveways, pathways, and shared car parks
Surfaces used for access, visitor parking, and shared parking areas are common property. Line markings, lighting, bollards, and gates also form part of this.Fire safety systems
All building-wide fire safety measures—such as hydrants, hose reels, emergency lighting, exit signs, smoke detection systems, sprinkler systems, fire doors, and panels—are common property and must be inspected and certified.External windows and balcony doors (in many strata plans)
In most older and many modern strata plans, windows and balcony doors sit outside the lot boundary, making them common property. This includes frames, tracks, rollers, and seals unless the plan states otherwise.Plumbing and drainage systems
Pipes, risers, sewer lines, stormwater drains, and water supply pipes that service more than one lot or sit outside the internal lot boundary are common property.Electrical wiring and shared services
This includes common electrical circuits, switchboards, cabling, shared internet/antenna systems, lighting, intercoms, and power infrastructure serving the building.Landscaping and external grounds
Gardens, retaining walls, fencing (unless specifically allocated by by-law), irrigation systems, and communal outdoor facilities remain common property.Building façades and balconies (structural components)
Balcony slabs, balustrades, and external finishes are usually common property, even where the usable surface is allocated to a lot owner.
The owners corporation is legally responsible for maintaining and repairing common property.
This includes timely repairs, planned maintenance, safety compliance, and ensuring building systems remain fit for purpose. Failure to maintain common property can lead to insurance complications, safety risks, disputes, and tribunal orders requiring rectification.
2. What Is “Lot Property” in Australia-wide
Lot property refers to the sections of a strata scheme that legally form part of an individual owner’s lot. It usually includes the internal airspace and finishes within the lot boundaries shown on the strata plan. Everything inside that boundary, unless defined as common property, is the owner’s responsibility to maintain and repair.
Lot property commonly includes:
Internal non-structural walls
Partition walls that do not support the building’s structure are typically lot property. Owners are responsible for paint, plaster, and any internal modifications, provided they comply with by-laws.Floor coverings
Carpet, tiles, timber flooring, vinyl, and underlay inside the lot are generally owned by the lot owner, even if the concrete slab beneath is common property.Light fittings and internal electrical components
Light fixtures, switches, power points, and circuit extensions that service only the lot are usually the owner’s responsibility. The main switchboard and building-wide circuits remain common property.Internal fixtures and fittings
This includes kitchen cabinets, benchtops, wardrobes, bathroom vanities, internal doors, mirrors, and similar items. These are upgrades and finishes that belong to the owner.Appliances owned by the lot owner
Items such as ovens, stovetops, dishwashers, air-conditioners (if installed inside the lot), and hot water systems located within the lot boundary are typically lot property, unless a by-law says otherwise.Internal plumbing and wiring servicing only that lot
Pipes, taps, shower fittings, and drainage inside the walls or floors that serve only the individual unit are generally lot property. Plumbing and wiring that branches off into multiple lots or remains in common risers is usually common property.
The individual owner is financially responsible for maintaining and repairing lot property.
This includes damage caused by wear, accidental impact, internal leaks, renovations, or deterioration of fixtures. Owners must ensure repairs comply with by-laws and do not affect structural components or other lots.
3. Why the Boundary Between Common and Lot Property Is So Confusing
The boundary between common property and lot property is determined by:
The registered strata plan, which sets the legal lot boundaries
The physical construction of the building (what is structural vs non-structural)
Any registered by-laws or approved renovations that alter responsibility
Because strata plans have changed over the decades, the age of the building directly affects how boundaries are interpreted.
How building age affects boundary rules
In Australia-wide, the definition of lot boundaries differs depending on whether the strata plan was registered before or after 1 July 1974, when the Strata Schemes (Freehold Development) Act introduced new mapping and boundary conventions.
1. Plans registered before 1 July 1974
Older plans often use unclear or inconsistent drafting conventions. Boundaries may be interpreted by:
The inner surface (inner face) of the wall
The midpoint (centreline) of the wall
The external face of the wall
Because these plans rarely use modern notations, the responsibility for items such as windows, balcony doors, waterproofing, or internal walls varies considerably. Each item must be interpreted based on the exact plan annotations.
2. Plans registered on or after 1 July 1974
Newer strata plans typically follow the standard rule:
The boundary is the inner surface of the lot, unless marked otherwise
Everything beyond that inner surface is generally common property
This means walls, slabs, windows, doors, and structural elements are usually common property unless dimensioned inside the lot boundary.
3. Very modern plans (post–1996 and post–2015 reforms)
Newer plans often contain clearer notation such as:
“Structural elements are common property”
“Lot boundary defined by interior face of wall”
Detailed diagrams clarifying windows, courtyards, terraces, and waterproofing
These plans remove much of the ambiguity seen in older schemes.
Why this matters
Because different eras of strata plans use different boundary conventions:
The same item may be lot property in one building and common property in another.
Windows, balcony structures, waterproofing, and pipes are the most frequent dispute points.
Reliance on assumptions—rather than the actual plan—often leads to complaints, repair delays, and NCAT disputes.
Understanding the building’s exact registration date, strata plan format, and annotations is the only accurate way to determine responsibility.
4. Who Pays for Repairs and Maintenance
As a general rule:
Common property is paid for by the owners corporation via levies
This includes structural elements, building services, fire systems, external walls, waterproofing, shared plumbing, and anything outside the lot boundaries.Lot property is paid for by the individual lot owner
This includes internal fixtures, non-structural walls, floor coverings, internal plumbing and wiring serving only that lot, and personal appliances or upgrades.
However, disputes commonly arise where the boundary of responsibility is not clear, particularly in situations where:
Damage spreads between lot and common property
Examples include water leaks, structural movement, or electrical faults that start in one area and impact another.A lot owner’s renovation affects common property
Works such as bathroom renovations, flooring upgrades, or wall removal can unintentionally damage waterproofing, structural components, or shared services.A failure of common property damages a lot
Issues like roof leaks, burst risers, or facade defects often raise questions about repairs, compensation, and insurance claims.Responsibility is shared between both
Some items involve a combination of lot property and common property components—for example, balcony surfaces (lot property) versus balcony slabs and balustrades (common property).
These overlap scenarios are the most common source of disputes at NCAT and are often resolved by interpreting the strata plan, examining the cause of the damage, and applying legal responsibility under strata legislation.
5. Typical Real-World Dispute Scenarios
Common disputes include:
A leaking balcony where the waterproofing membrane is common property but the tiles, grout, and finishes are lot property. Determining the cause of failure often decides who pays.
A burst pipe inside a wall that services multiple lots, making it common property, but damage inside the unit (flooring, paint, cabinetry) remains the owner’s responsibility unless insurance applies.
Water ingress through windows, which are common property in many older strata plans. The owners corporation may be responsible for replacing frames and seals, while internal damage belongs to the lot owner.
Cracking in internal walls that may be structural, requiring assessment to determine whether the wall forms part of the building’s structure (common property) or is a non-structural internal partition (lot property).
Electrical faults shared between apartments, where wiring or switchboards servicing multiple lots are common property, but internal circuits and outlets are lot property.
Mould caused by building defects versus inadequate ventilation, requiring an investigation of whether the source is a common property defect (roof leak, rising damp) or poor occupant behaviour (lack of ventilation).
These disputes often escalate because:
Owners refuse to pay, believing the damage originated from common property or was caused by another lot.
Committees delay decisions, often due to uncertainty about legal responsibility or fear of setting the wrong precedent.
Insurance coverage is unclear, especially where long-term defects, lack of maintenance, or exclusions complicate the claim.
Repairs are urgent but responsibility is disputed, causing damage to worsen and increasing the risk of health or safety issues.
6. How By-Laws Can Change Responsibility
By-laws can shift responsibility for:
Air-conditioning installations, making the lot owner responsible for the unit, condensate drainage, and any damage caused to common property.
Balconies, where exclusive-use or special-privilege by-laws can transfer responsibility for tiles, finishes, and even waterproofing to the lot owner.
Floor penetrations, such as bathroom renovations, where owners may take responsibility for waterproofing, tiles, and future leaks.
Solar installations, assigning repair, replacement, and roof penetration obligations to the lot owner using the roof space.
Exclusive-use areas, such as courtyards, car spaces, and storage areas, shifting ongoing maintenance obligations to the benefiting owner.
If responsibility is transferred by by-law:
The owners corporation may no longer be financially responsible for maintenance, repairs, or consequential damage relating to that item.
The lot owner may become responsible for all future maintenance and repair, including defects, wear and tear, and damage caused by deterioration.
Insurance responsibility may shift, meaning the lot owner may need additional coverage or may not be covered under the building’s main policy.
These changes apply only when a by-law is properly drafted, approved by special resolution, and registered with Australia-wide Land Registry Services.
Many disputes arise because:
By-laws exist but are not understood, leaving committees and owners unaware of who is responsible for what.
By-laws are drafted poorly, creating unclear or conflicting obligations that NCAT must later interpret.
By-laws were never properly registered, meaning they have no legal effect even though everyone assumed they applied.
7. When Damage Involves Insurance
Insurance disputes are common where:
Water damage spreads between lots, making it unclear whether the source is a common pipe, a lot-owned fixture, or an unapproved renovation.
Storm damage affects roofs and multiple apartments, requiring the insurer to determine whether the damage originated from common property failure or external factors.
Fire damage crosses property boundaries, complicating questions of responsibility, especially where the fire began inside a lot but spread through common areas or other units.
Critical insurance questions include:
Was the damaged property common or lot property?
Insurers need to identify which party is responsible for maintenance and repair before assessing liability.Did negligence contribute?
Claims may be reduced or denied if poor maintenance, ignored defects, or unsafe renovations contributed to the loss.Was the damage gradual or sudden?
Sudden events (burst pipes, storm impacts) are generally covered, while gradual issues (slow leaks, rising damp) are often excluded or limited.Was the property altered by unapproved renovations?
Unapproved bathroom works, balcony upgrades, or electrical changes may void parts of the claim or shift responsibility entirely to the lot owner.
Incorrect classification of property type, cause, or responsibility often leads to claim delays, reduced payouts, or outright claim rejection, and can trigger additional disputes between owners, committees, and insurers.
8. When a Lot Owner Can Be Required to Pay
A lot owner may be required to pay where:
They damaged common property
If an owner or their tradesperson causes physical damage—such as breaking tiles, cracking walls, or damaging waterproofing—they are responsible for the repair costs.They conducted unapproved works
Renovations carried out without approval, especially those affecting waterproofing, structure, or services, can shift all repair liability to the owner.Their renovation caused a defect
Faulty bathroom upgrades, balcony resurfacing, electrical work, or plumbing changes that later fail will generally be the owner’s responsibility to rectify.They breached a by-law
Noise, pets, flooring changes, or exclusive-use obligations often carry cost consequences when the breach leads to damage or nuisance.They failed to maintain exclusive-use areas properly
Where a by-law grants exclusive use—such as courtyards, balconies, car spaces, or gardens—the owner is usually responsible for maintaining and repairing those areas in good condition.
Disputes often arise where owners argue that:
The damage was pre-existing
Owners claim the issue was already present and should have been maintained by the owners corporation.The defect is building-wide
Arguments arise when an owner asserts that the problem is part of a broader structural or waterproofing defect affecting multiple lots.The owners corporation failed to maintain common property
If the dispute involves long-term leaks, structural deterioration, or ageing building components, owners often argue that poor maintenance—not their actions—caused the damage.
These disagreements frequently lead to investigations, insurer involvement, or NCAT proceedings, especially when responsibility overlaps between lot property, common property, and renovation impacts.
9. How These Disputes Escalate to NCAT
Most tribunal matters in this category arise after:
Repairs are delayed
When water ingress, structural issues, or safety defects are not addressed promptly, disputes escalate and owners seek orders for urgent action.Owners refuse payment
Owners challenge responsibility for repairs, argue incorrect billing, or dispute whether the damage is lot or common property.Insurance claims stall
Claims become disputed due to unclear cause, poor maintenance history, exclusions, or disagreements over whether damage is common or lot property.Emergency works are needed
Urgent repairs proceed before responsibility is agreed, leaving the parties to dispute costs afterward.The scheme funds repairs “without prejudice”
Committees often pay for repairs temporarily to protect the building, but then seek reimbursement—leading to disputes if the owner disagrees.
Once at NCAT:
Engineers or building consultants may be required
Independent experts are often needed to determine the cause of damage, responsibility, and repair scope.Strata plans are examined
NCAT reviews lot boundaries, common property definitions, and plan annotations to determine legal responsibility.By-laws are scrutinised
Exclusive-use, renovation, and responsibility-shifting by-laws are analysed to establish who must pay.Historical records are analysed
Past minutes, maintenance logs, defect reports, and correspondence are reviewed to assess whether the committee acted reasonably.Liability can be reassigned
NCAT may order that responsibility lies with the owners corporation, the lot owner, or both, depending on evidence.
Weak documentation—especially missing minutes, unclear by-laws, or lack of maintenance records—almost always disadvantages the committee and can result in adverse cost or repair orders.
10. Financial and Legal Consequences of Getting It Wrong
Misclassifying property responsibility can result in:
Invalid recovery of repair costs
If the scheme incorrectly charges an owner for work that is actually common property, NCAT can order the charges reversed.Refund orders against the scheme
The owners corporation may be forced to reimburse improperly billed expenses, sometimes spanning years of past decisions.Insurance claim denial
Incorrectly identifying whether an item is common or lot property can cause insurers to reject or reduce claims due to misrepresentation or lack of maintenance.Legal costs exceeding the repair itself
Small repair disputes often escalate into costly NCAT proceedings involving experts, lawyers, and extensive documentation.Personal liability exposure for committee members
If a committee knowingly misapplies responsibility or fails to act reasonably, NCAT may find individual members liable for decisions that breach their duties.Long-term neighbour disputes
Misclassification often damages relationships between owners, leading to ongoing complaints, hostility, and repeated tribunal applications.
These consequences frequently cost far more—in time, money, and conflict—than obtaining correct professional advice early.
11. Why Self-Managed Schemes Are at Higher Risk
Self-managed schemes are more exposed because:
There is no managing agent verifying responsibility
Without professional oversight, committees must interpret strata plans, by-laws, and legislation themselves, increasing the risk of incorrect assumptions.Committees rely on assumption
Decisions are often made based on what “seems logical” rather than what the strata plan or legislation actually requires, leading to misclassification of lot vs common property.Documentation is often incomplete
Missing minutes, unclear records of past works, and outdated strata plans make it difficult to prove responsibility when disputes arise or when the matter reaches NCAT.Insurance claim handling is inexperienced
Self-managed committees may struggle to present evidence, classify damage correctly, or respond to insurer queries, which can delay or jeopardise claims.Repairs are delayed while disputes continue
When owners and the committee disagree about responsibility, repairs often stall, increasing damage and escalating the conflict.
Most self-managed disputes occur not because of bad intentions, but because of uncertainty around boundaries, obligation gaps, and inconsistent documentation, all of which make it harder to prove compliance when a disagreement becomes formal.
12. When Professional Review Becomes Essential
Professional review is strongly recommended when:
Water ingress or structural damage exists
These issues often involve hidden causes, multiple contributing factors, and overlapping responsibilities that require expert assessment.Multiple lots are affected
Widespread damage usually indicates a common property defect, making accurate classification essential for insurance, liability, and repair planning.Insurance claims are involved
Claims can be denied or delayed if the source, responsibility, or maintenance history is unclear. Professional guidance ensures the claim is presented correctly.By-laws may override boundaries
Exclusive-use or renovation by-laws can shift responsibility in ways that committees may not immediately recognise, making review essential before making cost decisions.An owner disputes repair responsibility
Early professional input prevents the dispute from escalating and reduces the likelihood of NCAT intervention.Tribunal proceedings are likely
Once a matter reaches NCAT, evidence, documentation, and expert positioning become critical. Mistakes made early are difficult to correct later.
Independent review protects both the scheme and individual owners by ensuring the committee makes decisions based on accurate boundaries, correct legislation, and defensible documentation.
For self-managed committees, this is often the point where engaging professional support—such as assistance from Strata On Demand—can prevent costly disputes and ensure compliance before decisions are finalised.
Strata On Demand Can Help
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The most commonly used core services include:
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• AGM & EGM Chairing
• Budget Preparation
• Insurance Quote Coordination
• Work Order Management
• Tribunal Preparation
• Compliance Health Check
• plus more
Contact Us if your scheme needs professional support without paying for a full-service strata manager.
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