Common Property vs Lot Property: Who's Responsible for Repairs?

The water started coming through the bedroom ceiling on a Sunday night. By Monday morning there was a brown stain the size of a dinner plate and a steady drip into a saucepan on the carpet. The owner did what most people do: she called her strata manager and asked the body corporate to fix it. The strata manager said it sounded like it was coming from the bathroom of the unit above, which made it the upstairs owner's problem, not the body corporate's. The upstairs owner said his bathroom was fine and it was probably a common property pipe, which made it the body corporate's problem. Three weeks later, the stain had spread, nobody had lifted a finger, and the three parties were no closer to agreeing who should pay the plumber.

This is the most common dispute in apartment living, and it is almost always the same argument underneath: is the thing that needs fixing part of an individual lot, or part of the common property? Get that one question right and the responsibility usually sorts itself out. Get it wrong, and you can spend months and thousands of dollars arguing over a repair that might have cost a few hundred to begin with.

The Basic Rule: Where Your Lot Ends

When a building is subdivided into a strata or community titles scheme, the registered plan draws a boundary around each lot. Everything inside that boundary is lot property and is the owner's responsibility. Everything outside it - the structure, the shared services, the grounds - is common property and is the body corporate's responsibility, funded through your levies.

For most apartments, the boundary runs along the inner surface of the walls, floors and ceilings. A useful shorthand is the "paint line". Generally speaking, the paint and the surfaces you can see and touch inside your apartment are yours. The structure behind them - the concrete slab, the brick or block wall, the structural framing - is common property.

That means the body corporate is typically responsible for:

The building's structure: foundations, external and load-bearing walls, the roof, structural columns and slabs
Common services that serve more than one lot: the main water, sewer, gas, electrical and stormwater lines up to the point they branch off to an individual lot
Shared areas and facilities: foyers, stairwells, lifts, driveways, gardens, pools, gyms and common parking

And the lot owner is typically responsible for:

Internal wall surfaces, paint, and non-structural internal walls
Floor coverings (carpet, tiles, floorboards) laid over the structural floor
Fixtures and fittings inside the lot: kitchen cabinetry, the stove, internal doors, light fittings, the hot water system if it serves only that lot
Any pipe or wire that serves only that lot, from the point it branches off the common service

The exact boundary is set by your registered plan and your state's strata legislation, so the detail varies. But the structure-versus-surface principle holds almost everywhere in Australia.

The Grey Zones Where Arguments Start

If the rule were that simple, there would be no disputes. The arguments happen in the handful of places where the boundary is genuinely unclear or where the legislation treats things differently from what common sense suggests.

Windows and external doors. This is one of the most contested items in strata. The glass and frames sit on the boundary line. In many schemes the body corporate is responsible for the external window frames and the structural opening, while the owner is responsible for the glass, locks, handles and internal operation. In others it is reversed. Your by-laws and plan decide it, and it is worth checking before you assume.

Balconies. A balcony is often part of the lot, but the structural slab beneath it and the waterproofing membrane within it are commonly common property. So if balcony tiles crack because the membrane underneath has failed, that is frequently a body corporate repair, even though the tiles look like part of your lot. If they crack because someone dropped a barbecue on them, that is the owner's problem.

Pipes and wiring. The general test is how many lots the pipe or wire serves. A water pipe that runs down through the building serving every apartment is a common service. The moment it branches off to feed only your apartment, that branch is usually yours. The leak in our opening story almost certainly turned on exactly this question.

Hot water systems and air conditioning. A hot water unit or split-system air conditioner that serves only one lot is generally the owner's responsibility, even where it is physically located on common property such as a rooftop or a service cupboard.

Waterproofing membranes. Bathroom, laundry and balcony membranes are a frequent source of expensive disputes because they are hidden, they fail slowly, and they sit at the boundary. Where a failed membrane is original building work, it can also raise a separate question about building defects. We cover that in detail in our guides to waterproofing defects in new apartments and the six-year window for building defect claims.

A Quick Room-by-Room Guide

Here is the general position for the items owners ask about most. Treat it as a starting point, not the final word, because your plan and by-laws always govern.

Bathroom: The waterproofing membrane and the structural floor are usually common property. The tiles, vanity, toilet, shower screen and tapware are usually the owner's. A leak through the floor to the unit below often points back to the membrane.

Kitchen: Cabinetry, benchtops, the sink and appliances are the owner's. The branch plumbing serving only your kitchen is yours; the common stack it connects to is the body corporate's.

Balcony: The slab and membrane are usually common property; the tiles, balustrade glass and any owner-installed items are usually the owner's. Cracked tiles from a failed membrane lean body corporate; cracked tiles from impact lean owner.

Windows and doors: Genuinely scheme-specific. Check your plan and by-laws before assuming. External frames often body corporate, glass and hardware often owner.

Walls and ceilings: The structure is common property; the internal surface, paint and any non-structural partition you built are yours.

Pests: Structural timber pests such as termites and borers that threaten common property are usually a body corporate matter. Cockroaches, ants and rodents inside a single lot are usually the owner's. Infestations in common areas such as garden beds, bin rooms and shared roof voids are the body corporate's. Your by-laws may also impose cleanliness obligations that affect who is at fault.

When a By-Law Moves the Goalposts

The default boundary can be shifted by an exclusive use or special rights by-law. These are common for car spaces, courtyards, storage cages and rooftop areas. An exclusive use by-law gives one owner the sole right to use a piece of common property, and it very often comes with a catch: the by-law usually makes that owner responsible for maintaining the area they have exclusive use of.

So if you have exclusive use of a courtyard or a section of roof, do not assume the body corporate will maintain it just because it is technically common property. Read the by-law. The maintenance obligation frequently sits with you. This is one of the most overlooked traps when people buy a lot with an appealing extra like a private terrace or a large storage area.

How to Resolve a Disputed Repair

When responsibility is contested, the worst thing you can do is what the owners in our opening story did: stop, fold your arms, and wait for the other side to blink while the damage gets worse. Here is a more productive sequence.

Find the source, not the symptom. A stain on your ceiling tells you where water arrived, not where it came from. Get a plumber or building consultant to identify the actual point of failure. Responsibility follows the cause.
Read the plan and by-laws. Pull your registered strata plan and your scheme's by-laws. Look specifically for anything dealing with the item in question and for any exclusive use by-law that might apply.
Put it in writing to the body corporate. Notify your committee or strata manager in writing, describe the damage, and ask them to arrange an inspection. A written record matters if the dispute escalates.
Mitigate further damage. You generally have a duty to take reasonable steps to limit damage in the meantime, even while responsibility is unresolved. Keep receipts.
Escalate properly if needed. If you cannot agree, every state has a tribunal or commissioner that handles exactly these disputes. We walk through the options, costs and timeframes in how to deal with body corporate disputes and the more detailed mediation, tribunal or court guide.

Getting the boundary question right early is also a useful test of whether your fees are being spent well. If your body corporate is routinely pushing common property repairs onto individual owners, that is worth understanding when you next review whether your fees are too high.

Key Takeaways

The boundary decides almost everything. Inside the lot boundary is the owner's responsibility; the structure and shared services outside it are the body corporate's, funded by levies.
The "paint line" is a useful guide but the registered plan and your state's legislation set the exact boundary.
The grey zones cause the disputes: windows, balcony membranes, branch pipes, hot water units and air conditioners. Check before you assume.
Pests split by type: structural timber pests and common-area infestations are usually the body corporate's; in-lot pests are usually the owner's.
Exclusive use by-laws often shift maintenance back to the owner of the car space, courtyard or storage area.
Find the cause, not the symptom, put it in writing, and escalate to your state tribunal if responsibility cannot be agreed.

Compare body corporate fees across Australia at BodyCorporateFees.com.

This article is for informational purposes only and should not be considered legal advice. The boundary between lot and common property is set by your registered plan and the strata legislation in your state or territory, both of which vary and change over time. Always check your own plan and by-laws, and seek qualified advice for a specific dispute.