I. What Does “Unauthorized Construction on Private Property” Mean?

In Philippine law, “unauthorized construction on private property” generally covers situations where:

Someone builds on land they do not own, without the true owner’s consent (e.g., a neighbor extends a house, fence, or structure into your lot).
A possessor or tenant builds beyond what was allowed, or continues building despite the owner’s objection.
Structures are built without legally required permits, even if the builder is the owner, if the issue involves other private parties (e.g., building too close to a boundary, violating easements).

This is primarily governed by:

The Civil Code of the Philippines (rules on ownership, accession, builders in good or bad faith, easements, damages).
The Rules of Court (civil actions like ejectment, injunction, damages).
The National Building Code (P.D. 1096) and local ordinances (permits, zoning, demolition authority).

II. Ownership and the Right to Exclude

Under the Civil Code, the owner has the right:

To enjoy and dispose of the thing owned;
To recover it from any person who wrongfully possesses it; and
To exclude others from interfering, subject to the law.

If someone builds a structure on your land without your consent, they are interfering with your ownership. That interference may give rise to several possible civil, administrative, and sometimes criminal actions.

III. Key Civil Code Concepts: Accession and Builders in Good or Bad Faith

When somebody constructs on another’s land, the Civil Code’s rules on accession regarding immovables apply. The law asks essentially:

Who owns or has a better right over the land?
Was the builder in good faith or in bad faith?
Was the landowner in good faith or bad faith?

1. Builder in Good Faith

A builder in good faith is someone who builds believing they own the land or are legally entitled to build there, without knowledge of any defect in their title or right.

Typical examples:

A buyer whose title later turns out to be void, but who honestly believed it was valid.
A person relying on a mistaken but reasonable boundary or survey.

If the builder is in good faith and the landowner is also in good faith, the owner has options:

Appropriate the improvement (become owner of the building/fence/structure) by paying indemnity to the builder:
- Reimbursement of necessary and useful expenses; or
Require the builder to buy the land:
- If the value of the improvement is more than that of the land, the owner may be compelled by law to sell the land to the builder, at a fair price.

The law aims to prevent unjust enrichment and to balance interests when both parties acted honestly.

2. Builder in Bad Faith

A builder in bad faith is one who knows that they do not own the land (or have no right to build), yet proceeds with construction anyway—e.g.:

A neighbor who knows the boundary line but still extends a wall into your lot.
Someone who has been formally notified and demanded to stop but continues building.

If the builder is in bad faith and the landowner is in good faith, the owner may:

Appropriate the improvement without paying anything, or
Require the builder to demolish or remove the structures, at the builder’s expense, plus damages.

Bad faith is heavily penalized. The law discourages “build now, argue later” behavior.

3. Landowner in Bad Faith

There are situations where the landowner is in bad faith—for example:

The owner knows someone is building on their land by mistake, but intentionally keeps quiet to later take advantage of the finished structure.

Philippine jurisprudence generally does not allow an owner in bad faith to exploit the mistake of a good-faith builder. The rules on indemnity and options may shift in favor of the builder, and the owner may be liable for damages.

IV. Types of Legal Actions Available

The property owner (or person with a better right to possess) has several potential civil actions to choose from, depending on the circumstances:

1. Ejectment Cases (Forcible Entry & Unlawful Detainer)

Filed under Rule 70 of the Rules of Court, ejectment cases are summary actions focused on possession, not ultimate ownership.

Forcible Entry: Used when the builder or intruder takes possession of the land by force, intimidation, threat, strategy, or stealth, and then builds on it.
- Must generally be filed within one (1) year from the date of actual entry or discovery of stealthy entry.
Unlawful Detainer: Used when the person initially had lawful possession (e.g., tenant, lessee, tolerance by owner) but refuses to vacate even after the right to stay has ended and demand to vacate has been made.
- Must generally be filed within one (1) year from the last demand to vacate.

What can the court do in ejectment cases?

Order the defendant to vacate the property and remove unauthorized structures.
Award reasonable compensation for use of the property (rentals) and damages.
While ejectment suits are limited to possession, the fact that the defendant built unauthorized structures can be part of the factual basis for relief.

2. Accion Reivindicatoria (Action for Recovery of Ownership)

This is a real action to recover ownership of property plus possession. It is appropriate when:

You claim to be the true owner;
Another party is in possession and may have built structures on your land; and
The dispute over who owns the land is central.

In such cases, the court can:

Declare who the true owner is;
Order the removal, demolition, or appropriation of constructions;
Apply the Civil Code rules on builders in good or bad faith, and
Award damages (e.g., lost income, moral/exemplary damages if bad faith is proven).

3. Accion Publiciana (Action for Recovery of the Right to Possession)

This is used when:

You are not necessarily disputing ownership directly, or the issue is broader;
You want possession back after the one-year window for ejectment has expired.

It addresses better right of possession (possession de jure) and may also be combined with claims involving unauthorized structures.

4. Quieting of Title

If the existence of a structure and adverse claim (e.g., neighbor claiming part of your land) creates a cloud over your title, you may file an action to quiet title.

The court determines the extent and boundaries of your property.
It can declare adverse claims or encroachments null and void, and order demolition or removal of encroaching structures.

5. Injunction (To Stop Ongoing Construction)

If construction is ongoing and you want to stop it before it is completed, you may file:

An action for injunction with application for temporary restraining order (TRO) and/or preliminary injunction.

If granted, the court may:

Temporarily or permanently prohibit the builder from continuing the construction;
Maintain the status quo while the main case (e.g., ownership, possession) is resolved.

6. Damages

Along with the main civil action, an owner can claim various forms of damages, such as:

Actual or compensatory damages: rental value, cost of restoring the land, loss of crops, etc.
Moral damages: if there is bad faith or malicious conduct causing anxiety, humiliation, or similar injury.
Exemplary damages: to deter clearly wrongful behavior and set an example.
Attorney’s fees and litigation expenses, when justified by law and circumstances.

V. Administrative Actions: LGU and Building Officials

Unauthorized structures often violate the National Building Code (P.D. 1096) and local zoning ordinances. Even if the dispute is between private individuals, government authorities can play a major role.

1. Building Permits and Occupancy Permits

Construction generally requires a building permit from the City/Municipal Building Official.
After completion, an occupancy permit may be needed before the building can be legally used.

Constructing without these permits, or violating approved plans (e.g., building outside your lot), is a violation.

2. Notices, Stop-Work Orders, and Demolition

The Building Official or LGU may:

Issue a Notice of Violation;
Issue a Stop-Work Order;
Ultimately, order removal or demolition of structures that violate the Building Code or local ordinances, after due process.

If the structure is on private property of another, the LGU action is administrative, independent of civil actions between the parties. However, the LGU’s orders can support the landowner’s civil claims (and vice versa).

VI. Criminal Liability (In Certain Cases)

Although many disputes over unauthorized structures are civil, some fact patterns may give rise to criminal cases, for example:

Malicious mischief (damage to property) under the Revised Penal Code, if the construction involves the destruction or alteration of another’s property with malicious intent.
Usurpation of real rights (e.g., squatting-type behavior) depending on the specific law in force and circumstances.
Falsification or fraud if a party used falsified documents (e.g., fake titles, fake permits) to support construction.

Criminal liability depends heavily on intent, evidence, and specific statutes involved.

VII. Barangay Conciliation and Pre-Litigation Steps

For disputes between residents of the same city or municipality, the Katarungang Pambarangay system usually requires barangay conciliation before going to court (except in certain cases, like when urgent legal action is needed).

Typical non-judicial or pre-litigation steps include:

Gathering Documents and Evidence
- Transfer Certificate of Title (TCT) or other proof of ownership.
- Tax declarations, approved survey plans, subdivision plans.
- Photos, videos, and written communications regarding the construction.
Formal Written Demand / Notice
- Send a demand letter to:
  - Stop construction;
  - Demolish encroaching structures; or
  - Vacate the premises.
- Clear written demands help in proving bad faith and help start the clock for certain actions (e.g., counting the one-year period for unlawful detainer).
Barangay Conciliation
- File a complaint with the Punong Barangay.
- Attend mediation/conciliation sessions.
- If settlement is reached, it may be embodied in a barangay settlement which can have the effect of a final judgment if not repudiated.
- If no settlement, you obtain a Certificate to File Action, which is required for most court cases involving neighbors.

VIII. Special Situations

1. Encroaching Walls and Fences

Common scenario: A neighbor builds a fence or wall that encroaches on your property.

If the neighbor is in good faith (genuine boundary mistake), courts may apply builder-in-good-faith rules, allowing options of:
- Requiring the neighbor to remove the encroachment; or
- Selling the affected strip of land (if reasonable and consistent with the law); or
- Allowing you to appropriate and keep the structure with proper indemnity.
If the neighbor is in bad faith (aware of the boundary but ignores it), you can demand removal at their expense and claim damages.

2. Constructions by Tenants, Lessees, or Occupants by Tolerance

A tenant or lessee usually cannot build permanent structures without the owner’s consent.
If they do, the landlord may:
- Treat the structure as improvement belonging to the land (with obligations depending on good or bad faith and agreements); or
- Demand removal and restoration upon expiration or termination of lease, plus damages where appropriate.

If they refuse to vacate or remove structures after lease expiry, an unlawful detainer case is often the primary remedy.

3. Informal Settlers (Squatters) on Private Land

If informal settlers build dwellings on private property:

Civil remedies (ejectment, recovery of ownership) remain available to the landowner.
There are also special laws and government programs governing eviction and demolition of informal settlements, usually requiring:
- Adequate notice;
- Consultation;
- Sometimes relocation or financial assistance, subject to law and policy.

Demolition of houses of informal settlers is sensitive and often involves coordination with LGUs, the sheriff, and sometimes social welfare agencies.

4. Co-ownership and Party Walls

If the land or wall is under co-ownership, or the wall is a party wall (serving two properties):

A co-owner or adjoining owner generally cannot unilaterally alter or build on common property in a way that injures the rights of the other.
Actions may involve partition of co-owned property or injunction and damages to address unauthorized works.

IX. Evidence and Practical Litigation Considerations

To succeed in legal actions relating to unauthorized construction, the party must usually prove:

Ownership or better right to possess the land (title, tax declarations, deeds, surveys).
Facts of construction:
- When and how the structure was built;
- That it is indeed within the boundaries of the landowner’s property;
- The extent of encroachment (surveys, engineer’s reports).
Good faith or bad faith:
- Knowledge of boundary lines;
- Previous warnings or demands;
- Conduct suggesting intentional encroachment or concealment.

Courts may also consider the proportion between the land affected and the value of improvements, the feasibility of demolition, and equity.

X. Prescription and Laches

While some actions (like ejectment) are subject to strict time limits, issues of ownership and encroachment may be subject to:

Ordinary acquisitive prescription of real property (through open, continuous, exclusive, and notorious possession in the concept of owner for a certain period).
Extraordinary prescription and rules on laches (equitable doctrine where long inaction may bar a claim even before full prescription).

This means that a landowner who does nothing for many years while someone openly occupies and builds on their land may risk losing legal advantage, depending on the circumstances.

XI. Strategy: How Owners Typically Proceed

In practice, property owners often proceed in stages:

Consultation with a surveyor or geodetic engineer to confirm boundaries.
Demand letter to the builder/neighbor, asking to stop construction or remove encroachments.
Barangay conciliation for disputes between neighbors in the same locality.
If unresolved:
- Injunction: to stop ongoing construction;
- Ejectment (if within the one-year period based on possession issues); or
- Accion reivindicatoria / accion publiciana / quieting of title, depending on whether the dispute is over possession or ownership and how long it has lasted.
Simultaneous or subsequent administrative complaints to the LGU/building official for code violations and possible demolition orders.
Potential criminal complaints, in clear cases of fraud, malicious mischief, or other penal offenses.

A well-planned approach often combines civil, administrative, and barangay mechanisms, tailored to the specific facts.

XII. Final Notes

The legal framework on unauthorized construction rests on a balance between protecting ownership, discouraging bad faith, and preventing unjust enrichment.
Determining whether someone is a builder in good faith or bad faith is a factual matter; courts look closely at evidence of knowledge, notice, and behavior.
Actual cases can be highly fact-specific: even small differences in notice, boundary documentation, or prior agreements can change the outcome.

Because of this, anyone involved in a real dispute over unauthorized construction on private property in the Philippines should consider consulting a lawyer who can examine the title, surveys, and documents, and choose the most appropriate combination of remedies under the Civil Code, the Rules of Court, and applicable special laws and local regulations.