What is horizontal division in a single-family home?

Horizontal division in a single-family home is a legal mechanism that allows a property originally designed as one dwelling to be converted into two or more independent units, both legally and physically. This arrangement, regulated in Spain by the Ley de Propiedad Horizontal (Law on Horizontal Property), is essential for those looking to divide inheritances, generate rental income, or formalise informal living situations (for example, two families living on separate floors).

Applying horizontal division to a house originally built as a single residence enables each resulting unit to be legally registered as an independent property. Each one can have its own title deed, cadastral number, utility meters, and even a separate mortgage. This, of course, has a significant impact on the property’s value as well as its potential for use or sale.

At our architecture studio, we’re seeing a growing number of enquiries about this process—especially in high-demand areas like the Costa Blanca, where many homeowners see it as an opportunity to optimise their property’s use or begin a real estate investment project.

Is it possible to apply horizontal division to a single-family home?

The short answer is yes—it is possible to apply horizontal division to a single-family home, but not in every case. To do so legally, the property must meet certain urban planning and construction requirements. It’s not enough to simply divide a house physically or in theory—each resulting unit must have appropriate living conditions, independent access, separate installations, and must comply with local urban planning regulations.

In areas like the Costa Blanca, where large houses or older villas are often built on spacious plots, the possibility of dividing a single-family home is particularly appealing. Many of these properties already feature separate floors, street-level access, or even individual kitchens and bathrooms. However, this doesn’t necessarily mean the setup can be legalised without a detailed preliminary study.

Common reasons for dividing a single-family home

The decision to apply horizontal division in a single-family home is usually driven by practical or strategic needs. These are the most common reasons:

  • Inheritance distribution: when several heirs wish to divide the property without selling it

  • Partial sale of the property: to monetise part of the home without losing full use

  • Letting a floor or section: very common in homes with independent basements or upper floors

  • Regularising existing arrangements: for example, houses already used as separate duplexes

  • Architecture projects focused on profitability: for investment, tourist use, or residential letting

In all these cases, the horizontal division framework provides a solid legal basis that ensures legal certainty for owners, future buyers, or tenants.

Legal requirements for applying horizontal division to single-family homes

To carry out a horizontal division in Spain, certain legal and technical requirements must be met. These can vary depending on the municipality, but generally include:

  • Each resulting unit must have its own independent access (either a direct entrance from the outside or from a shared space)

  • Each unit must meet minimum requirements for liveability and usable surface area

  • Technical division plans must be drawn up by a registered architect

  • An urban compatibility report must be obtained from the local council

  • There must be no express prohibition in local planning regulations or the original title deed

It’s important to note that some urban planning regulations do not allow an increase in the number of residential units on a given plot. That’s why our studio always begins this type of project with a thorough urban planning feasibility study.

What the horizontal property law and civil code say

The Horizontal property law, which governs the legal framework for this type of division, states that a property may be divided horizontally when the conditions exist to create independent private units.

According to Article 5 of this law:

"The title may be granted by the sole owner of the building (...) to establish a system of ownership by floors or premises that can be used independently."

In turn, the Spanish civil code establishes that property owners may freely dispose of their assets, provided they do not infringe upon the law or the rights of third parties.

This legal framework provides the foundation for carrying out a horizontal division of a single-family home in a lawful and secure manner—provided all required technical reports and permits are in place.

Municipal licences and urban planning permits required

An essential part of the process involves administrative procedures with the local council, including:

  • Requesting a prior urban planning report

  • Submitting the technical division project

  • Paying applicable urban development fees

  • Obtaining a building permit if works are needed to adapt the home

  • Submitting the final completion certificate (where applicable)

The process may vary depending on the municipality—especially in towns across the Comunidad Valenciana and the Costa Blanca, where urban planning rules are often specific and some areas are subject to additional protection due to their historical or landscape value.

The architect’s role in the horizontal division of a single-family home

The architect plays a key role in this type of process. At our architecture studio, we take care of:

  • Producing detailed plans of the current layout and proposed changes

  • Ensuring that the new dwellings meet habitability standards

  • Preparing the technical report justifying the division

  • Coordinating with municipal technicians

  • Supervising any works required to ensure legal compliance

We also guide the client throughout the entire process—from the initial urban feasibility study to obtaining the final division certificate.

Advantages of horizontally dividing a single-family home

There are many advantages, especially when approached strategically:

  • Increases the property’s value, as it becomes two separately registrable and sellable units

  • Facilitates inheritance or donation procedures

  • Allows legal rental of part of the property, including for tourist accommodation

  • Improves tax efficiency, as different regimes can be applied to each unit

In areas like Jávea, Dénia, or Moraira—right in the heart of the Costa Blanca—this approach has become a popular option for families and small-scale investors.

Common limitations: Technical, legal, and urban planning

It’s not all advantages—there are certain limitations that can prevent or complicate the process:

  • Plots where only one dwelling is permitted per land unit

  • Properties under heritage protection or located in areas with landscape restrictions

  • Lack of independent access or separate installations (water, electricity, drainage)

  • Restrictions in the original title deed or outdated urban planning regulations

This is why consulting with professionals before starting any procedure is essential. A misinterpretation could result in the rejection of the application—or even lead to penalties.

Impact on the title deed and land registry

Once horizontal division of a single-family home is approved, the property’s title deed must be updated. This is done through a new notarial deed that specifies:

  • The number of independent units created

  • The private and communal square metres

  • The ownership share (quota) of each new dwelling

  • The boundaries and access points for each unit

The new deed is then submitted to the Land Registry, where new cadastral references and, where applicable, new postal addresses are assigned. From that moment on, each unit is recognised as a separate legal entity.

Taxes and fiscal implications of dividing a property

As with any legal operation involving real estate, horizontally dividing a single-family home carries tax implications. Some of the most important include:

  • Notary and registry fees: costs for the new deed and its registration

  • Stamp Duty (AJD): this varies depending on the autonomous community

  • IBI (Property Tax): recalculated individually for each new dwelling

  • Personal Income Tax or Capital Gains: if one of the units is sold after the division, it will be subject to taxation

In tourist areas of the Costa Blanca, where many divisions are carried out for rental purposes, it’s also essential to consider the tax obligations arising from letting or tourist use, depending on the applicable legal framework.

Step-by-step process for horizontal division

Here is a practical summary of the process for applying horizontal division to a single-family home:

  1. Urban feasibility study carried out by an architect

  2. Preparation of the technical project, including plans and a written report

  3. Request for a municipal urban planning report

  4. If required, application for a minor or major works permit

  5. Execution of necessary alterations to adapt the property

  6. Final works and habitability certificate issued by the architect

  7. Notarial deed for the horizontal division

  8. Registration with the Land Registry and cadastral update

How much does It cost to horizontally divide a single-family home?

The cost of horizontally dividing a single-family home can vary significantly depending on several factors: the municipality where the property is located, the current state of the building, the complexity of the technical project, local urban planning regulations, and whether any renovation work is required.

Beyond notarial and registration fees, it’s also important to consider the involvement of professionals such as architects, quantity surveyors, or specialist legal advisers—especially if the property presents legal or structural complexities. Additionally, each local council applies its own fees, which can influence the overall budget.

For this reason, we always recommend requesting a personalised study prepared by a professional team. At our architecture studio, we carry out a preliminary feasibility analysis so that each client has a clear understanding of the steps involved and the costs associated with their specific case.

This approach not only helps avoid surprises, but also allows for informed decisions based on accurate, project-specific information.

Professionals required for a horizontal division

To carry out the process correctly, it’s essential to have a professional team capable of coordinating the legal, technical, and fiscal aspects:

  • Architect: responsible for the technical project and ensuring compliance with regulations

  • Urban planning solicitor: helpful for interpreting local planning laws

  • Notary: drafts the new deed for the horizontal division

  • Municipal technician or quantity surveyor: if the project requires professional site supervision

At our architecture studio, we offer full coordination of all these professionals—so the client doesn’t have to worry about procedures or paperwork.

Horizontal division in single-family homes for rental purposes

One of the most common uses of this legal arrangement is to transform a single-family home into two or more apartments for residential or tourist rental. This requires meeting specific conditions:

  • Independent entrances

  • Occupancy licences for each unit

  • Separate electricity and water meters

  • Declaration of the economic activity (if rented out)

In high-demand areas like the Costa Blanca, this approach allows property owners to maximise profitability while maintaining full control over property management.

Real cases of horizontal division in the Comunidad Valenciana

In recent years, we’ve worked on numerous horizontal division projects throughout the Comunidad Valenciana, particularly in areas such as:

  • Jávea: conversion of villas into two independent apartments

  • Benissa: country houses transformed into rural dwellings

  • Alicante city: multi-storey homes renovated and divided into separate rental flats

Every project starts with a personalised analysis and is adapted to the urban and legal context. The possibilities are many, but the approach must always be technical and professional.

Opinion: Is it worth dividing your home? How can an architecture studio help?

Horizontal division in a single-family home is a great opportunity—when done legally, safely, and with proper planning. It allows a property to be adapted to new circumstances, maximised in value, used more efficiently within the family, or even turned into a source of additional rental income.

At La Quinta Fachada Arquitectura, we’ve guided many clients through this process, particularly across the Costa Blanca and other municipalities in the Comunidad Valenciana. Our experience combines technical expertise, urban planning sensitivity, and efficient project management.

If you’re considering dividing your home, get in touch. We’ll be happy to help you give your property a new life—one that respects its essence and enhances its value.