Most property buyers naturally focus on what they can see.

They inspect the bedrooms, walk through the living areas, look at the terrace and imagine how they will use the garden or swimming pool. When a property has an additional guest apartment, a converted garage or an enclosed roof terrace, those spaces appear to be an ordinary part of the home.

The asking price will often reflect them as well.

However, the property that physically exists and the property described in the official documentation are not always identical. In Spain, differences can exist between the actual building, the Escritura, the Registro de la Propiedad and the Catastro.

These discrepancies may remain unnoticed for many years. They often only become a problem when the owner decides to sell.

When the documents do not match the property

Before placing a property on the market, its documentation should be compared with the building as it currently stands.

This normally means checking:

• the Escritura or title deeds;
• an up-to-date Nota Simple from the Land Registry;
• the information recorded in the Catastro;
• the actual layout and constructed surface area;
• planning and community documentation where relevant.

During these checks, it may become clear that part of the property does not appear in the official records.

Typical examples include:

• a basement or underbuild converted into accommodation;
• a covered and enclosed terrace;
• an extension added to the original house;
• a garage converted into a bedroom or apartment;
• a guest house, summer kitchen or storage building;
• an official surface area that is smaller than the building in reality.

The owner’s response is often completely understandable:

“But the property was already like this when we bought it.”

That may be true, but it does not automatically solve the legal or registration problem.

Can unregistered construction simply be added later?

Buyers are sometimes told that an unregistered extension is not a serious issue because it can always be added to the title deeds at a later date.

The explanation often sounds simple: an architect measures the construction, prepares a certificate confirming its age and description, and the additional square metres are then registered through the notary and Land Registry.

In certain situations, this may indeed be possible.

A qualified architect or technical architect may be able to establish the current measurements and age of a building or extension. This information can then be used to investigate whether the construction can be declared and incorporated into the official documentation.

However, a certificate of age does not by itself guarantee that the construction can be fully legalised or registered.

The following factors may also need to be considered:

• the planning classification of the land;
• municipal building regulations;
• permitted building volume and plot occupation;
• protected land or coastal restrictions;
• the use of the additional space;
• possible involvement of a community of owners;
• whether common elements have been altered.

For this reason, statements such as “you can register it later” should never be treated as a guarantee without professional verification.

A detached villa can be very different from an apartment

There is an important distinction between an extension built on the private plot of a detached villa and an alteration made to a property within a community of owners.

With a detached house, the investigation will often focus on planning regulations, plot boundaries, permitted building area, the age of the construction and the correspondence between the physical building, the Catastro and the Land Registry.

This is especially relevant when viewing older villas for sale in Calpe or villas for sale in Moraira that include guest accommodation, underbuilds, covered terraces or later extensions.

In an apartment building, townhouse complex or urbanisation governed by a comunidad de propietarios, the position may be more complicated.

An enclosed terrace or enlarged living area may affect:

• the horizontal division of the building;
• the registered description of the individual property;
• common elements belonging to the community;
• the participation coefficient assigned to the property;
• the rights of neighbouring owners;
• the community statutes or constitutive title.

Depending on the exact alteration and the legal correction required, approval from the community of owners may be necessary.

The required voting majority depends on the specific circumstances. Certain changes may require a qualified majority, while amendments affecting the constitutive title or community statutes can, in some cases, require unanimity.

That means a physical alteration that has existed for many years may still be difficult to register if the necessary community approval was never obtained.

The problem often appears when the owner wants to sell

Imagine that someone bought an apartment fifteen years ago with a roof terrace that had already been enclosed and converted into an additional bedroom.

The buyer paid for a property with that extra room, used it for many years and maintained the home on the assumption that the room legally formed part of the apartment.

When the property is later placed on the market, the documentation shows a smaller apartment without the additional bedroom.

The owner may initially believe that the records can simply be updated before completion.

However, the investigation may reveal that the alteration affects a communal roof terrace, changes the registered horizontal division or requires community approval that was never granted.

If the necessary consent cannot be obtained, the property may need to be sold with the discrepancy fully disclosed.

This can affect:

• the buyer’s willingness to proceed;
• the bank valuation;
• mortgage approval;
• the timetable of the sale;
• the final selling price.

This issue can also arise with older apartments for sale in Albir and in other established coastal developments where terraces, storage spaces or communal areas have been adapted over the years.

Unregistered square metres do not always have the same value

A property’s market value is not based solely on the number of rooms that can be seen during a viewing.

Legal certainty, mortgageability and resale potential are also important.

If part of a property is not correctly documented, possible consequences include:

• a lower official valuation;
• difficulty obtaining mortgage finance;
• delays during legal and technical investigations;
• architect, notary, municipal and registration costs;
• a reduced number of interested buyers;
• a lower achievable sale price.

The current owner may not have caused the problem. They may have relied on what they were shown or told when they originally purchased the property.

Nevertheless, the discrepancy remains attached to the property.

The previous seller and estate agent may no longer be involved, but the current owner must deal with the consequences.

What should a buyer investigate?

A discrepancy does not automatically mean that a property is a bad purchase.

Differences between the physical reality, the Catastro and the Land Registry occur regularly in Spain, particularly with older properties. Many situations can be corrected.

The important point is to investigate them before the buyer becomes legally committed.

Relevant questions include:

• Does every part of the building appear in the title deeds?
• Does the registered surface area match the actual property?
• Does the Catastro show the same layout and measurements?
• Was planning permission obtained for the alteration?
• Can a technician confirm the age and exact measurements?
• Is the property part of a community of owners?
• Have any common elements been used or altered?
• Was community approval required?
• Can the alteration genuinely be registered?
• What would the process cost?
• Could the discrepancy affect a mortgage or future resale?

The answers should be obtained from the relevant qualified professionals. Depending on the property, this may include an independent lawyer, architect, technical architect, notary, Land Registry, municipal planning department or community administrator.

The role of the estate agent

An estate agent is not a replacement for a lawyer or architect.

However, an agent should not ignore obvious discrepancies or make confident promises about matters that have not been professionally checked.

If part of a property is not registered, the correct response should not be:

“Do not worry, you can sort that out later.”

A more responsible explanation would be:

“This part of the property does not currently appear to be correctly registered. We cannot yet confirm whether it can be fully regularised. The situation should be investigated by the appropriate legal and technical professionals before you make a final decision.”

This may be less convenient during a sale, but it allows the buyer to make an informed decision.

The purpose of due diligence is not to create unnecessary alarm. It is to distinguish between a correctable administrative discrepancy and a problem that may seriously affect ownership, financing or resale.

A good property sale should still make sense years later

At the notary, the seller receives the purchase price, the buyer receives the keys and the transaction is completed.

But an unresolved legal or registration issue does not disappear after completion.

It remains with the property.

Sometimes it only becomes visible ten or twenty years later, when the buyer becomes the next seller and discovers that the property is not officially described in the way they always believed.

For that reason, the most important question is not only:

“How can we sell this property today?”

It should also be:

“What is the buyer legally acquiring, and will they be able to sell it again without unexpected problems?”

At Casas Real, we believe a successful property transaction should not only reach completion. The information and documentation should also remain reliable when the property returns to the market many years later.

Before buying a home in Spain, always make sure the physical property is compared with its legal and administrative documentation. An attractive extra room today should not become an expensive problem tomorrow.

This article provides general information only and does not constitute legal, technical or tax advice. Every property and alteration must be assessed individually by the appropriate qualified professionals.