Habitability and minimum floor area in Spain

In Spain, it is perfectly legal to sell a 10-square-metre flat. Or an 8-square-metre one. Or even a 6-square-metre one. A dwelling's legal status does not depend solely on its floor area, but on whether the property has a certificate of occupancy (cédula de habitabilidad), a first-occupancy licence or another administrative authorisation confirming its residential use. Older homes built in accordance with the rules in force at the time retain their legal status even if they do not meet today's minimum floor-area requirements.

This means that the resale market includes a real, though difficult-to-quantify, number of homes, particularly in major cities, that would fall below the minimum standards now required by law for any new dwelling. A buyer can purchase one of these properties without anyone warning them.

What the rules say and why they vary so widely

At national level, the Spanish Building Code (Código Técnico de la Edificación, CTE) establishes that a home intended for private use must have a minimum floor area of 36 square metres, including a living-dining room, kitchen and bathroom. This is the national reference threshold that Hogarfax uses as an indicative operational benchmark.

But that is where the complexity begins. Each autonomous community sets its own requirements, with minimums ranging from 20 to 40 square metres. Madrid and Murcia, for example, require at least 40 m² for new homes, while Catalonia sets the threshold at 36 m² and the Basque Country at 35. In regions such as Andalusia, the Canary Islands, Extremadura and Galicia, minimums start at 24, 25 or 26 square metres.

The real issue: conversions, subdivisions and the legacy of older housing stock

Spain's housing affordability crisis has placed enormous pressure on the existing housing stock, with visible consequences in the market.

• Converting commercial premises into homes. Limited supply and high prices have made commercial units a common target for developers and private owners. Many conversions are carried out with all the proper permits. Others are not. Verifying this means reviewing the administrative file, not the sales listing.
• Subdivision of homes. A large flat may legally be divided into two or three smaller units provided each meets the minimum standards. Yet in high-pressure markets such as Madrid, Barcelona, Valencia and Palma, some subdivisions skirt or openly breach floor-area and habitability requirements, then reach the market as independent homes.
• Existing flats with old licences. These are the hardest to spot. A 40 m² studio laid out in the 1980s may have been informally divided into two units, or may have a layout that would meet no current standard. But if it has an old licence, it can be sold.

Why this is an urban problem, not a rural one

Outside major urban centres, this problem is marginal. In depopulated rural Spain and most medium-sized cities, homes have the space they have because that is how they were built, and there is no pressure to divide them up. The market does not justify the work.

It is in Madrid, Barcelona, Valencia, Palma, San Sebastián and other very expensive cities that scarcity makes otherwise uneconomic projects profitable: subdividing, converting and compressing space. Buyers under pressure to find something on the market may end up purchasing a property whose actual floor area falls below current habitability minimums or whose legal restrictions limit future renovation.

What Hogarfax does, and its limitations

At Hogarfax, we compare the floor area available in cadastral records with the indicative 36 m² threshold derived from the CTE as a baseline national reference.

Two points must be made clear. First, cadastral floor-area data does not always match the property's actual area exactly: the Cadastre may include common areas or hold outdated information. Second, we do not apply the specific regional or municipal rule for each property, as that would require checking the exact rules of every municipality in real time.

What we do provide is an early warning: if the registered floor area is below 36 m², that is a reason to check which licences the home holds, whether the cadastral area is correct and whether any restrictions would affect future renovation or reconfiguration.