What is Common Property and what isn't?

30 May

Depending on the number of units in your property group or the layout of your complex, it might not always be easy to determine what is common property and what isn't.

If you own, manage, or rent a unit or townhouse in South Australia, understanding common property is one of the most important things you can do. It determines who is responsible for repairs, who pays the bill when something goes wrong, and how disputes get resolved. Yet for many people living in strata or community title developments, the boundaries of common property remain surprisingly unclear.

The Two Acts You Need to Know

In South Australia, the legal framework for shared-title properties is split across two Acts. Older developments (those where the strata plan was deposited before 1 June 2009) are governed by the Strata Titles Act 1988 (SA). Newer developments created from 1 June 2009 onwards use the Community Titles Act 1996 (SA). While the principles around common property are broadly similar under both Acts, it is worth knowing which one applies to your property — and your strata manager can confirm this for you.

The South Australian Government has also been progressing the Statutes Amendment (Community and Strata Titles) Bill 2024, which proposes a range of modernising reforms including stronger protections for residents, greater transparency from managers and developers, and improved dispute resolution. While these reforms are primarily focused on governance and management obligations rather than the definition of common property itself, they reflect a broader push to improve accountability across strata and community title living in South Australia.

What the Law Says About Common Property

Under the Strata Titles Act 1988 (SA), common property is defined as:

Any land or space that is not within a unit
Any pipe, cable, wire, duct or drain that is not for the exclusive use of a unit
Any structure that is not for the exclusive use of a unit installed before the deposit of the strata plan
Any structure installed by a strata corporation as part of the common property
Any other structure on the site committed to the care of a strata corporation as part of the common property

Unless your strata plan indicates otherwise, the boundary of a unit is the internal surface of the walls, floors, and ceilings. In plain terms: everything on the inside of those surfaces belongs to the unit owner, while the structures themselves — the roof, guttering, external walls, and foundations — are common property, owned collectively by all unit holders through the strata corporation.

What Does "Common Property" Actually Include?

To make this more practical, here are the main categories of common property that come up most frequently in day-to-day strata management:

Roofs and gutters - The entire roof structure is common property, regardless of which unit sits beneath it. Even if a cracked or damaged tile is directly above one particular unit, responsibility for the repair lies with the strata corporation.

External walls - The outer skin of the building belongs to the strata corporation. This includes brickwork, cladding, render, and external paintwork.

Windows and doors (original) - Original windows and external doors installed as part of the original building structure are generally considered common property, even though they are accessed from within a specific unit. This is a frequent source of confusion.

Shared driveways, paths, and gardens - Any land or pathway used by more than one unit, including visitor parking areas and garden beds in communal areas, is common property.

Building services - Shared pipes, cables, ducts, drains, and electrical infrastructure serving the whole complex are common property. This includes things like main water risers, common area lighting circuits, and intercom systems.

Common area facilities - Lifts, pools, gym equipment, and similar amenities shared by all residents are maintained by the strata corporation as common property.

What Is NOT Common Property?

Just as important is understanding what falls within the unit owner's responsibility.

Internal fitments - Fixtures and fittings inside a unit, such as kitchen cabinetry, internal doors, floor coverings, and bathroom tiles, belong to the unit owner.

Branch plumbing - A common question involves drains and pipes. The main drain running from the street into the complex and serving all units is common property. However, where that drain branches off to serve a single unit exclusively, the branch pipe becomes the responsibility of that unit owner. If your kitchen or bathroom drain blocks and the blockage is within your unit's branch drain, it is your repair to organise and pay for.

Unit subsidiaries - A unit subsidiary is an area defined on the strata plan that is not common property but is allocated for the exclusive use of one unit. Common examples include a private balcony, a courtyard, a garden area, or an allocated carport. The unit owner is responsible for maintaining their unit subsidiary, though the rules around this can vary — always check your strata plan and the relevant Act.

Renovations and alterations within the unit - Any additions or changes an owner has made inside their unit boundary (such as an added internal partition wall or a replacement tapware) are the owner's responsibility. Note that works affecting common property, such as installing a new air conditioner on an external wall, generally require approval from the strata corporation.

Real-World Examples

Understanding the theory is one thing; seeing how it plays out in practice is another. Here are some scenarios that regularly arise:

Scenario 1: A cracked roof tile A resident in Unit 3 notices water staining on their ceiling and traces it to a cracked roof tile directly above their bedroom. Even though the tile sits perfectly above Unit 3 and no other unit is affected, the roof is common property. The strata corporation is responsible for arranging the repair and covering the cost through strata levies.

Scenario 2: A blocked drain A unit owner calls a plumber to investigate a slow-draining bathroom. The plumber finds the blockage is in the branch drain inside the unit — the pipe that runs exclusively from that bathroom to the main drain. Because this branch serves only the one unit, it falls within the unit owner's responsibility. The owner pays the plumber directly. Had the blockage been in the main shared drain outside the unit, it would have been a strata matter.

Scenario 3: Ageing windows An owner wants to replace the original timber windows in their unit with modern aluminium frames. Because the original windows are part of the building's original structure, they are common property — meaning the owner cannot simply replace them without going through the strata corporation. Any alteration to common property requires approval, and in many cases the strata corporation may take on the work itself. If you are unsure, seek written clarification from your strata manager before committing to any works.

Scenario 4: A leaking balcony Water is leaking through a balcony floor into the unit below. Whether the balcony is a unit subsidiary (exclusive use) or common property depends on what is shown on the strata plan. If it is a unit subsidiary, the owner of that balcony is responsible for its maintenance. If it is common property (as is sometimes the case with balconies in older buildings), the strata corporation must act. This is why checking the strata plan is so important — assumptions can be costly.

Scenario 5: Air conditioning installation A unit owner wants to install a split-system air conditioner. The indoor unit will sit inside the unit (owner's responsibility), but the outdoor compressor needs to be mounted on the external wall (common property). Even if the owner pays for the unit and installation themselves, they must first obtain approval from the strata corporation before any work affecting common property proceeds. Proceeding without approval can result in the owner being required to restore the property at their own cost.

Why This Matters

The reason common property boundaries matter so much comes down to two things: responsibility and cost. If a maintenance issue arises and it is incorrectly attributed to the wrong party, repairs can be delayed, disputes can escalate, and people can end up out of pocket unnecessarily.

With over a quarter of South Australians now living in strata or community-titled properties, issues around shared spaces and maintenance responsibilities affect a significant and growing number of people across the state. Getting these basics right from the start saves a great deal of frustration.

For tenants, understanding common property helps you know who to contact when something needs fixing - your property manager or landlord for issues within your unit, and the strata manager for common property concerns. Reporting the right issue to the right person means faster resolution.

For unit owners, clarity around common property boundaries is essential for budgeting, insurance purposes, and ensuring you do not inadvertently carry out works that require strata approval.

For property managers, knowing the boundaries means you can direct maintenance requests appropriately, avoid unnecessary delays, and ensure the right party is invoiced.

When in Doubt, Ask

Strata and community title law in South Australia is not always straightforward, and the boundaries of common property are not always obvious — particularly in older complexes, irregularly shaped buildings, or situations involving shared services. If you are uncertain about who is responsible for a particular area or item, always check the strata plan first and then contact your strata manager for guidance. A quick enquiry upfront is far better than an expensive dispute after the fact.

This article is intended as general information only and does not constitute legal advice. For specific guidance on your scheme's obligations, contact a licensed strata manager or legal adviser.