Aircon ledge: common property or part of your own lot
Exclusive use of a ledge feels like ownership, and in a strata development the two are separate questions. Habit settles one. A plan filed with the land registry settles the other, and most owners read that plan for the first time during an argument.
By Team Snowflake | Updated 7 Aug 2026
Exclusive use is not the same as ownership
Nobody else can step onto your aircon ledge, and that settles nothing about who owns it. Three true things get mistaken for a boundary. Only your unit opens onto the ledge. Only your equipment stands on it. Only you pay to keep that equipment running. None of the three is a title, and together they describe a habit rather than a right.
The general shape is simple, and the exceptions are where owners get caught. What sits inside a lot is generally the owner's, and looking after it falls to the owner. What sits outside is usually common property, which the corporation maintains and manages. Some things standing inside a lot are still common property by definition, including structural elements and the ducts that serve more than one unit. Use is a weak guide, and it fails in both directions.
The ledge is where this bites hardest, because it sits right on the seam. It lies outside your walls, and nobody else can reach it. It carries your machine, and it forms part of the building's outer shape. Two estates on the same road can answer the question differently. Neither answer is a mistake.
What a management corporation is, and where its powers come from, is a separate subject. The guide on what an MCST is covers that ground, including how common property is defined in general terms. HDB flats have no management corporation at all, and shared property in an HDB estate sits with the town council instead. For a flat, read the guide on HDB aircon ledge problems.
Where the answer is actually written
Your development's strata title plan settles the boundary. It is registered with the Singapore Land Authority, and it marks out what falls inside a lot and what falls outside. BCA's guidance for owners puts it directly: an owner identifies common property by referring to that plan. A copy can be bought from SLA, and there is a fee for it.
The management office should be able to answer from the plan without you buying a copy. BCA's worked example deals with grilles and louvres rather than ledges, and it splits the job between both sides. If the feature falls within the plan, maintaining it is the owner's. If the owner is unsure, the office is who they ask. The office, in turn, is expected to read the plan and keep a record of what it found.
That last part is the one to press on. An office that has never written the answer down will improvise it, and improvised answers move when the officer moves. Ask for a determination taken from the plan, not a view. Then ask where that determination is filed.
Why the estate next door answers differently
The designation is fixed at design stage, long before anyone moves in. Under planning rules, an aircon ledge can be included in a unit's strata area, and a ledge included that way counts toward the development's floor area. It can also be kept out of the strata area, and a non-strata ledge within a set width does not count. The choice belongs to whoever designed the development, which is why neighbouring estates give opposite answers.
Planning guidance also asks that ledges be sized so the equipment on them can be reached and worked on later. That expectation says nothing about who owns the platform. It is a reminder that the space was drawn with upkeep in mind, whichever side of the line it landed on.
What each answer changes
Three things move with the answer, and one does not. Approval, repair of the platform, and access for building work all shift. The exception is any opening cut through the external wall. The outer face and the structure behind it are shared in nearly every development, so that part needs approval either way.
Approval is the first thing to change. If the ledge falls inside the lot, changing what stands on it runs into the by-laws on works, hours and appearance. If the ledge is common property, the decision is not the owner's alone. BCA states the rule plainly: an owner cannot alter or change common property without the corporation's approval. The same holds where a job unavoidably uses common property, such as anchor points landing on an external wall.
Repair of the platform is a separate bill from repair of the machine. Spalling concrete, a failing finish or a corroded railing on a common property ledge is estate work, funded through the contributions every owner pays. The same defect inside a lot falls to the owner of that lot. Neither answer reaches the condenser, which stays the owner's throughout.
Access changes in a quieter way. Common property leaves the corporation with a standing reason to be there, since facade cycles, painting and repairs to shared structure all reach the ledge. Equipment sitting on it may have to be worked around or moved for that. Inside a lot, the reasons to come in are narrower. How anyone safely reaches a high ledge is a different question again, planned by whoever commissions the work.
| The question | Ledge drawn inside the lot | Ledge drawn as common property |
|---|---|---|
| The questionChanging what stands on the platform | Ledge drawn inside the lotBy-laws on works and appearance still apply | Ledge drawn as common propertyThe corporation's approval is the starting point |
| The questionRepairing the slab, finish or railing | Ledge drawn inside the lotSits with whoever holds the lot | Ledge drawn as common propertyEstate work, funded through contributions |
| The questionThe condenser and its brackets | Ledge drawn inside the lotThe owner's, brackets included | Ledge drawn as common propertyAlso the owner's, brackets included |
| The questionReaching the ledge for building work | Ledge drawn inside the lotFewer standing reasons to come in | Ledge drawn as common propertyFacade and repair cycles reach it |
| The questionCutting through the external wall | Ledge drawn inside the lotApproval on either answer | Ledge drawn as common propertyApproval on either answer |
Three objects stand on the same square metre
Separate the slab, the bracket and the machine before asking who answers for what. They are three objects, and one plan can give them three different answers. Owners picture a single thing called the ledge, which is why the answer feels contradictory when it arrives.
The machine is the owner's in every version of this. BCA is explicit for units inside a lot: maintaining the air-conditioning units and their supporting systems falls to the owner. Nothing about the boundary changes that.
The bracket is the part most people never think about. The exterior-features rules treat it as a feature in its own right. A metal or concrete bracket fixed to the building and to externally mounted equipment counts. So does a similar supporting frame. Those rules define that equipment to include an air conditioning unit and its condensing equipment. So the frame under your condenser has a standing of its own, apart from the slab below and the machine above.
Exterior features carry an upkeep duty, and that duty follows whoever answers for the feature. BCA describes that person as the owner of the building it is installed on, or whoever has daily charge of managing and maintaining it. Its own split, offered as non-exhaustive, places the supporting system of an air-conditioning unit on the owner's side. The list is prefaced with the same caveat used throughout this page: it depends on the strata title plan. Penalties sit behind the duty where a feature or its support falls because nothing was kept up.
| The object | What it is | What the plan changes about it |
|---|---|---|
| The objectThe slab or platform | What it isBuilding structure, or part of the lot | What the plan changes about itWho repairs it, and who approves changes to it |
| The objectThe bracket or frame | What it isAn exterior feature in its own right | What the plan changes about itLittle: the supporting system usually stays the owner's |
| The objectThe condenser | What it isEquipment the owner bought and runs | What the plan changes about itNothing: it is the owner's on either answer |
When there is no ledge at all
Some units were never given a platform, and the equipment hangs off the wall instead. BCA is specific about that case. Where no aircon ledge is available, units installed on the second storey or above must sit on a stainless-steel supporting frame. The frame and its fixings need checking for corrosion and looseness as they age.
If an installer offers to bracket the unit to the wall because the ledge is full, read that as a change of category rather than a workaround. Standing equipment on a slab and fixing it to the outer face of a building are different acts. The second one lands on shared structure in most developments, and it adds a new exterior feature to the building. Settle that before anyone drills, not after.
What to settle before an install or a replacement
A third answer sits between yours and the estate's. A management corporation can make a by-law giving an owner exclusive use and enjoyment of part of the common property, or special privileges over it. Conditions can be written into that by-law, including payments. The part stays common property throughout. What moves is who may use it, and on what terms.
How long the arrangement runs decides how hard it is to pass. An arrangement of under a year needs an ordinary resolution. One running between one and three years needs a special resolution. Anything longer than three years needs a ninety per cent resolution. A lasting arrangement is therefore the hardest kind to create, and few estates hold one for condensers.
An exclusive use by-law does not move the boundary. The plan is untouched, and the allocated part is still common property. It also does not follow from an approval letter. Permission to install and a by-law conferring exclusive use are different instruments, made by different means, and neither is evidence of the other.
One further limit is worth knowing. Where ordinary use of common property ends, and exclusive use begins, is a question of fact. Legal commentary notes that the line has not been drawn consistently. Treat any confident general answer with care. In practice, most condensers standing on common property here rest on approval and long habit rather than on a by-law of that kind.
Collect these answers in writing before the work is booked. Keep them with the unit's records rather than in a chat thread.
- Which side of the lot boundary the ledge falls on, answered from the plan rather than from memory
- Whether any exclusive use by-law attaches to that ledge, and what conditions came with it
- Who the office records as answerable for the platform, and who for the brackets holding the condenser
- What making good means if brackets are moved or new holes are needed
- Where all of that is filed, so the next officer and the next owner get the same answer
Where this page stops
Several neighbouring questions belong elsewhere. Outdoor unit placement is its own decision, and so is condenser clearance around the machine. Forms and sequencing for a private job sit in the condo installation checklist. Lobby and function-room equipment is condo common-area aircon, run by the corporation on its own account. Rental aircon responsibility between a landlord and a tenant runs on a separate track, and it leaves the boundary where it was. The condo defects liability period on a new development is its own subject too.
Strata boundaries here sit under the Building (Strata Management) Act, renamed in 2025. The earlier initials, BMSMA, stood for Building Maintenance and Strata Management, and plenty of search traffic still uses them. Reading the statute will not answer your question, though. Two documents held by your own estate will: the strata title plan, and the by-laws lodged for that plan. This page maps the question. It is not advice on your matter, and where the answer carries real cost it belongs with someone who can read both documents for you.
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