How to divide an existing building into condominiums without carrying out works
- Ana Carolina Santos
- 4 days ago
- 5 min read
Portugal allows owners to divide existing buildings under the horizontal property regime without the need for significant construction works. This has important legal and practical implications, especially for those seeking to economically leverage a property solely through the legal reorganisation of the units.
The Concept of Horizontal Property: Legal Framework
Horizontal property is a legal regime that allows dividing a building into autonomous units, each with a distinct owner. It differs fundamentally from the traditional concept of indivisible whole ownership.
The Legal Regime of Urbanisation and Building (RJUE) states that a building can be constituted under the horizontal property regime without any prior works, provided it meets certain technical and safety requirements.
Dividing a building into horizontal property is not an urban operation subject to licensing or prior communication, allowing owners to legally reorganise existing properties by simply altering the registry.
Fundamental Requirements for Constitution of Horizontal Property
Not every building can be divided under horizontal property. The law establishes mandatory preconditions:
Compliance with Habitability Standards
The building must meet fundamental safety and habitability conditions, according to the Municipal Council’s prior assessment. This evaluation considers:
Adequate load-bearing structure
Absence of collapse risks
Compliance with health standards
Guaranteed independent access
Viable connection to general water, sewage, and electricity infrastructures
If any of these requirements are not met, the building cannot be constituted under horizontal property, regardless of other circumstances.
Access and Infrastructure
The law explicitly requires the building to have independent access and direct connection to public infrastructure networks. Isolated buildings or those without viable network connection cannot legally be divided.
Procedure for Constitution under Horizontal Property
The formation of horizontal property follows defined procedural steps:
1. Certification by the Municipal Council
The owner requests certification from the Municipal Council confirming the building meets the requirements for horizontal property constitution. This request may be accompanied by prior communication (Comunicação Prévia) of use if the owner also wishes to register information about unit uses.
The Council has established deadlines to analyse and issue this certification. Municipal recognition is a mandatory prerequisite for any subsequent registry entry.
2. Opinion on Common Areas
Certification includes evaluation of the state of common parts — stairs, corridors, roofs, facades, load-bearing structure.
If common parts are unsuitable for use, the Council may refuse certification. Owners may be required to undertake rehabilitation of common areas before finalising horizontal property.
3. Property Registry
After municipal certification, the owner can register the horizontal property in the land registry. This legally transforms the property structure, creating autonomous units with potentially different owners. The registry includes:
Detailed property description for each unit
Identification of private areas
Identification of common areas
Ownership coefficients for each unit
Participation quota in expenses
Definition of Autonomous Units
An autonomous unit under horizontal property is an independent habitation or usage unit, with its own access or through shared circulation.
Compliance of Each Unit
Each unit must satisfy:
Functional independence: capable of autonomous use
Structural safety: location must not compromise overall building safety
Habitability: for residential units, meet height, lighting, ventilation requirements
Access: own entrance or via common stairs/corridors
Legal subdivision does not change physical compartment features. Units with inadequate size (e.g., low attics) need specific evaluation.
Common Areas vs. Private Areas
Law clearly distinguishes two categories:
Private Areas
Belong exclusively to a single unit owner:
Interior compartments
Private balconies
Private terraces
Private storage
Each owner has exclusive use rights, may deny third-party access.
Common Areas
Jointly owned by all unit owners:
Stairs
Access corridors
Lobbies
Non-private roofs
Load-bearing structures
Facades
Collective electricity, water, and sewage installations
Common green spaces (if any)
Unit owners have usage rights but cannot modify or damage common areas without consensus.
Economic Implications of Horizontal Property
Division generates financial consequences for each owner:
Participation Quota
Each unit is assigned a participation quota in common expenses, proportional to its size relative to the entire building.
An owner with 30% of total area pays 30% of common maintenance, cleaning, insurance costs, etc.
Mandatory Common Expenses
Include:
Load-bearing structure maintenance
Facade painting and rehabilitation
Stairs and corridor repair
Cleaning of common areas
Maintenance of shared installations
Building insurance
Water supply and sewage (in many cases)
Use Change without Works
After constitution, owners can change unit usage without works if administrative procedures are followed.
Examples:
Convert residential unit to commercial (office)
Establish tourist accommodation unit
Create professional office
Install small retail
Use changes require prior communication to Municipal Council but are not urban operations requiring licensing if no structural modifications.
Practical Advice for Horizontal Property Division
✓ Obtain Technical Opinion Early
Contact Municipal Council to check basic safety and habitability conditions. Some buildings require prior works preventing horizontal property without major intervention.
✓ Inspect Common Areas
Assess condition of stairs, roofs, facades, and load-bearing structure. Buildings with serious structural faults may need rehabilitation before horizontal property, leading to unexpected costs.
✓ Calculate Participation Quotas
Precisely determine private and common areas. Incorrect quotas cause expense distribution inequalities and disputes.
✓ Review Specific Horizontal Property Legislation
The regime has complementary laws (notably the Civil Code) defining owner obligations, coexistence rules, expense management, and dispute resolution. Familiarise before dividing.
✓ Consult Qualified Professionals
Architects and engineers can evaluate technical feasibility ensuring each unit meets basic functional and safety standards.
Limitations and Infeasibilities
Not all buildings are divisible into horizontal property:
Buildings at serious seismic risk needing prior structural reinforcement
Buildings without independent access (legally impossible)
Buildings without infrastructure connections (legally unfeasible)
Buildings with structural deficiencies (Council may refuse certification)
Buildings in protected areas may face division restrictions
Distinction from Other Division Forms
Horizontal property differs from other legal property structures:
Divided Ownership (Traditional)
Shared property among owners by percentage. Each owns the whole building in a shared share. Less suitable for multi-unit buildings.
Condominium (Different Concept)
Horizontal property is a specific form where common parts belong jointly to all unit owners.
Fractional Lease
A single owner subdivides the building into units for rental but retains full ownership.
In Brief
Horizontal property allows legal division of existing buildings without major works, given basic safety, habitability, independent access, and infrastructure access are met. Constitution requires prior municipal certification of compliance.
Each created unit is autonomous with potentially distinct owners sharing expenses per registered quota. Owners can change use within legal limits without works.
Horizontal property is not automatic; buildings with severe faults or legal/infrastructure restrictions may not qualify.
Clarify Your Building’s Division Feasibility
Owners wishing to economically leverage buildings via horizontal property face complex questions: does the building meet minimum requirements? What legal duties apply? How to organise ownership?
AC-Arquitetos offers technical assessment of feasibility compliant with law and safety, habitability, and accessibility standards. We identify constraints and guide on municipal procedures. Contact us to check your building’s eligibility and steps.
