The core answer
When water drips from your ceiling, the question is rarely just "is it the upstairs neighbour?" Work through three steps in order: where did the water escape, is that part private or common property, and who was careless or failed to maintain it.
The rule (Condominium Act and Civil and Commercial Code). The unit is private property. Structure, drainage systems and equipment kept for shared use are common property, which the juristic person must manage and maintain. A person who damages another's property intentionally or negligently commits a tort under Section 420. Where damage comes from a structure that is defective or poorly maintained, Section 434 makes the person in possession liable first, and the owner liable instead if the possessor took proper care. A tort claim is time-barred after one year from knowing of the wrong and the wrongdoer (Section 448).
Our practical view. Do not argue about fault first. Within a few days, photograph and film the damage, give written notice to the upstairs owner and the juristic person, and have a technician or engineer identify the source. Good evidence settles most disputes early and is the foundation of a case if one is needed.
For unpaid common fees, see our common fee arrears guide. This guide does not repeat it.
1. Which leaks are the upstairs unit's problem and which are common property?
What the law says (Condominium Act B.E. 2522, Sections 4, 13 and 15).
- Private property is the unit itself, plus any structure or land set aside for that unit owner.
- Common property is the part of the building that is not a unit, and other property kept for shared use or benefit. Section 15 gives examples, including structure and constructions for the stability and protection of the building, and systems built for safety or the environment inside the building, such as drainage and wastewater treatment.
- Section 13, paragraph 2: the floor and the walls dividing two units are jointly owned by the owners of those two units, and how the right is used follows the regulations.
- Section 13, paragraph 3: an owner may not do anything to their own unit that could affect the structure or stability of the building.
The Act does not state, for every case, "this water pipe belongs to X". The answer comes from the juristic person's regulations, the building plans and the registration documents of your project.
| Where the leak is | General tendency | Who to notify first |
|---|---|---|
| Tap, supply hose, fixture, washing machine, water heater in the upstairs unit | Private property of the upstairs unit | Upstairs owner or tenant, and the juristic person |
| Pipes or waterproofing under the upstairs bathroom floor | Could be either; check structure and regulations | Upstairs unit and juristic person |
| Main pipe or riser shared by several units | Usually common property | Juristic person |
| Slab or wall junction with cracks | Floor between units is jointly owned by both owners | Both units and the juristic person |
This table shows tendencies only. It is not a legal conclusion. The result depends on your project's documents and the technician's report.
2. When is the upstairs owner liable?
What the law says (Civil and Commercial Code, Sections 420 and 434). Under Section 420, a person who intentionally or negligently and unlawfully damages another's property must pay compensation. Examples that may fit: leaving a tub to overflow, or renovating a bathroom without proper waterproofing so water seeps down.
Section 434 applies where damage arises because a structure was defective or not maintained sufficiently. The person in possession of the structure must pay. If that person took reasonable care to prevent the damage, the owner must pay instead.
Practical view. The injured owner should at least be able to show that the water came from that unit and how much damage there is. That is why a technician's report naming the leak point matters most.
If the upstairs owner says "the pipe was just old, it is not my fault", that does not release them automatically. Section 434 also speaks of inadequate maintenance. A court looks at the facts of each case. We cite no court decision here.
3. Is the upstairs tenant liable?
A tenant whose carelessness causes the leak, for example forgetting to turn off a tap, may be liable under Section 420 like anyone else. If the tenant is the person in possession of the unit, Section 434 may also apply to them. This depends on the facts, and we do not cite a specific decision.
Between landlord and tenant, Section 562 makes the tenant liable for loss or damage to the leased property caused by the tenant's fault or that of people living with them, but not for damage from proper use. That is the landlord and tenant relationship, not liability to the unit below.
Advice. Notify both the owner and the tenant. Ask the juristic person for who is living in the unit, as far as it will tell you. Let the owner and tenant sort out their own sharing of liability. Do not give up your claim against either until the cause is clear.
4. When is the juristic person or building manager liable?
What the law says (Condominium Act, Sections 33 and 36). The juristic person exists to manage and maintain common property. The manager carries out that purpose, and in urgent and necessary cases may on their own initiative order or do things concerning the safety of the building, as a reasonable person would look after their own property.
What this means in practice. If the source is a common pipe or system, and the juristic person was told and did not inspect, repair or stop the leak, the extra damage may be a basis for a tort claim against it. So what matters is when it was told and what it did. That is why notice must be in writing with a clear date.
We found nothing in the Act making the juristic person automatically liable for every loss inside a unit. If the cause is purely inside the upstairs unit, the juristic person may not be liable, but it should help by coordinating access and isolating the water. A project's regulations may say more.
5. What evidence should you keep?
- Photos and video. Show the stains, ceiling, walls, floor and damaged items, with date and time in the file. Film over several days to show the leak continuing.
- Technician or engineer report. It should identify the leak point, the cause and the extent of damage. If access to the upstairs unit is needed, ask for consent and have the juristic person attend as a witness.
- Written notice. To the upstairs owner and the juristic person, with proof of delivery such as a postal receipt or a read message.
- Repair quotes and receipts. For the unit and for damaged belongings, with photos of the items, purchase price and age.
- Juristic person records. Incident logs, messages, and whether earlier leaks were reported.
- Unit documents. Copy of the unit title, regulations, plans and your insurance policy.
On limiting your loss: Section 442 applies Section 223 by analogy. Section 223 lets a court consider whether the injured party failed to avert or reduce the damage. So move belongings, switch off wet circuits and get the water stopped at once.
6. Where does insurance fit?
A building policy held by the juristic person (if any) and your own policy, such as contents cover or third-party liability cover, differ widely in scope and exclusions. Some do not cover gradual seepage. We have not reviewed any policy, and we have not confirmed that the Act requires any particular cover. Read your own policy, and ask the insurer about its notice period before you repair or remove the damage.
7. What can you claim, and what are the steps?
What the law says (Civil and Commercial Code, Section 438). The court decides, according to the circumstances and the gravity of the wrong, how and how much compensation is paid. Compensation includes returning the property lost or paying its value, together with damages for any other loss caused.
Practical view. Common items are repair of the ceiling, walls, floor and electrics, the value of damaged belongings, and temporary accommodation if the unit is genuinely unlivable. Keep quotes and receipts.
The order we usually suggest:
- Report the leak and ask for it to be stopped.
- Send a demand letter with the technician's report and repair estimate, with a reasonable reply deadline.
- Negotiate. If you agree, put it in writing: amount, payment date and who does the repairs.
- If there is no agreement, consider suing.
Smaller claims. The Taling Chan Civil Court FAQ states that a summary case (kor-dee mano-sa-re) is one where the disputed amount does not exceed 300,000 baht. The procedure is simpler than an ordinary case. Ask the court directly about filing steps and fees. We have not confirmed whether a leak dispute can be a consumer case, which depends on whether a party is a business operator, so do not assume it.
For timing and costs, see how long a civil case takes and lawyer fees in Thailand.
8. The deadline: how long do you have?
What the law says (Civil and Commercial Code, Section 448). A claim for damages from a tort is time-barred one year after the injured person knew of the tort and who must pay, or ten years after the wrongful act. If the act is also a criminal offence with a longer criminal limitation period, the longer period applies.
Where people go wrong. Months of talking in the hope the other side will pay can use up the year unnoticed. We have not confirmed which notices or negotiations interrupt the limitation period, so have a lawyer check the start date in your case. If you knew which unit was the source from day one, treat the year as running from then.
9. Hypothetical example
Hypothetical example. Mr. A lives in unit 405 and finds water dripping from the bathroom ceiling early in the month. He films it, gives the juristic person written notice and has a technician inspect. The technician finds a cracked drain pipe under the floor of unit 505. The juristic person tells the owner of 505, who rents the unit out. Mr. A writes to both owner and tenant with a repair quote. The key questions are who is responsible for that under-floor pipe under the regulations, and whether the owner of 505 had maintained it. Every project differs. This example is not a forecast of any outcome.
10. First-week checklist
- Stop the water if you can; ask the juristic person to close the valve.
- Photograph and film before cleaning up.
- Move valuables and switch off wet circuits.
- Give written notice to the juristic person and the upstairs owner; keep proof of delivery.
- Hire a technician or engineer for a report naming the leak point.
- Ask for the regulations and plans.
- Check your policy and notify the insurer if it may apply.
- Keep every quote and receipt.
- Write down the date you knew the source and who was responsible, and count one year.
- Do not repair away all traces before the evidence is complete.
Further reading
- Unpaid common fees: a guide for condominium juristic persons
- How long a civil case takes in Thailand
- Lawyer fees in Thailand 2026
- Buying a resale condo from a private seller
Start a condo leak claim with a technician's report that names the source, then give written notice to both the upstairs owner and the juristic person, because the tort limitation period is only one year from knowing of the wrong and who is liable.
We advise on demand letters, legal notices and property disputes. Initial consultation is free — call +66 92 254 2045 or send us the details. See also demand letters, legal notices, real estate and civil litigation.
This guide is published by Suwanvara Law Firm — a Khon Kaen law firm established in 1986. General information only, not legal advice on a specific matter.
