Urban land, rural land and houses that arrive on a lorry: mobile homes and prefabs

October 2026

A house is not just an object: it is an object in a place. And in architecture, the place is what counts. The same house that is perfectly legal on a plot in town can, two hundred metres away in the farmland, be an infringement the town hall can pursue with no time limit.

We get asked almost every week: “can I put a mobile home on my land?”, “what about a wooden house, which doesn't involve building work?”, “the Cadastre says it's urban, doesn't it?”. To answer, we need to separate two questions: what land it is, and what you want to put on it. Let's take it step by step.

First, the land

In the Valencian Community, each municipality's local plan classifies its whole territory into three classes of land (article 28 of the TRLOTUP):

Land class	What it is	Can I build a house?
Urban	The town or city that is already developed: streets, water, electricity, sewers.	Yes, if the plot is a building plot (solar) and you comply with the zone's bylaws: heights, site coverage, setbacks.
Developable	Land earmarked for growth, but not yet developed.	Usually not, until the sector is developed. It can take years.
Non-developable (rústico)	The countryside: irrigated farmland, dry farmland, hills. It can be common or protected.	Only under very strict conditions on common land, and almost never on protected land.

State law puts it differently, talking about “rural” and “urbanised” land according to its actual situation, but to know what you can build, what counts is the classification in your municipality's local plan.

“The Cadastre says it's urban”

It is one of the most expensive mix-ups we see. The Cadastre has its own definition of urban land, designed for collecting taxes, and it does not match the planning one. A storeroom in the farmland can pay urban IBI (property tax) because the Cadastre considers it part of an area with services, and still be on non-developable land where a home cannot be built. What you can build is set by the local plan, not by the IBI bill.

A house on rural land: the rules

On common non-developable land, Valencian law allows a detached family home only if all of these conditions are met at the same time (article 211.1.b of the TRLOTUP):

A plot of at least one hectare per home (10,000 m²), or more if the local plan requires it.
The house must not take up more than 2% of the property. On one hectare, 200 m² at most.
It must be outside natural run-off channels and respect existing trees.
It must provide its own drinking water, waste disposal and wastewater treatment.
It must not form a population cluster with other homes.

And a detail many people do not know: on urban land, the town hall has 15 years to act against works carried out without a permit. On non-developable land, the current law sets no time limit (article 255.5 of the TRLOTUP). An illegal building in the countryside may have to be demolished even if it has been standing for years.

The mobile home: vehicle or house?

It is the big selling point: “it doesn't need a permit because it has no foundations, you put it in and take it out”. The Supreme Court settled this in its judgment 1917/2024 of 5 December: a mobile home is treated as a prefabricated house, not as a caravan or a trailer, because what matters is what it is used for, and it is used to live in. Therefore, it needs a planning permit.

Valencian law already said so: the “placing of prefabricated houses and similar installations, whether temporary or permanent” is subject to a permit (article 232.c of the TRLOTUP). And state law adds that in these cases silence from the town hall does not mean yes: express authorisation is required.

It arrives on a lorry and is put in place in a day. But what decides whether it needs a permit is not how it arrives, but what it is used for. Photo: Barry Lewis · CC BY 2.0, via Wikimedia Commons.

What this means in practice:

On a campsite, mobile homes are governed by tourism regulations (Decreto 10/2021): they are accommodation units without foundations, the pitch contract cannot exceed one year, and they do not become your home.
On a rural plot of your own, “for weekends”, it needs a permit like any house, and therefore has to meet the same conditions: one hectare, 2%, its own services. The Generalitat has made clear that a temporary permit for residential use is not possible on this land.
On an urban plot, it also needs a permit and has to comply with the bylaws and the Building Code (Código Técnico), like any home.

The Valencian Land Protection Agency keeps an eye on it. In the municipality of Elche alone, at the start of 2025 it had 37 open cases over prefabricated or wooden houses and 18 over containers or fixed caravans on rural land.

Prefabricated, modular or wooden house: what paperwork it needs

Here the confusion is different. Nobody disputes that a prefabricated house needs a permit; what is sold is that it “comes ready-made” and that the paperwork is minimal. And that is not the case.

In law, a prefabricated house is a residential building, just like a brick one. That means it needs a project signed by an architect (articles 2 and 10 of the Ley de Ordenación de la Edificación) showing that it complies with the Building Code (Código Técnico de la Edificación) on its specific site: its structure, its anchoring to the ground, its insulation, its fire safety, its ventilation and its drainage. CE marking or factory certificates refer to the products, not to the house placed on your plot, and they do not replace the project.

What we find when we review these houses is almost always the same:

The structure is not designed for here. The Vega Baja is one of the areas with the highest seismic risk on the Iberian Peninsula, and a house designed for another climate and another soil has to be recalculated, together with its anchoring to the foundations.
The windows and glazing fall short. They often do not meet the insulation values required by the Building Code, or they cause condensation at the junctions.
Fire and ventilation. Timber and some panels need treatments or protection that the catalogue does not include, and indoor ventilation is often left unresolved.
On the other side, often nobody signs. Very often the person selling the house is a salesperson, not a technician, and the catalogue takes no responsibility for your plot, your permit or what happens in ten years' time.

Show homes are sold from a catalogue. What the catalogue does not include is the project that makes that house legal on your plot. Photo: Joe Mabel · CC BY-SA 3.0, via Wikimedia Commons.

A real case: 60 m² of timber in Catral

We recently prepared a quote for a client who had chosen a 60 m² prefabricated timber house for their plot. To be able to apply for the permit, the house needed us to:

Review the manufacturer's technical documentation and check what complied and what did not.
Adapt the design: layout, openings, windows, glazing and insulation at the junctions.
Draw up the basic design and construction project, with its report, drawings, details and budget.
Calculate the structure and its anchoring to the foundations.
Process the permit and respond to the town hall's requests.
Supervise the works and sign the final certificate.

And on top of that there was the building engineer (arquitecto técnico) for the works, health and safety coordination, the geotechnical study, fees and construction tax. In other words: the project and paperwork for a prefab are practically the same as for a conventional house of the same size. What you save, if anything, is assembly time on site.

We are not against building in a factory. We are against being sold the idea that a house can skip the project.

If you build the house to live in yourself, as the self-developer of a single home, you are not required to take out ten-year structural insurance (seguro decenal). But if you sell it before ten years have passed, you will have to take it out for the remaining period, unless the buyer expressly waives it.

Before buying the plot or the house

Check the land class in the local plan, not in the Cadastre or the listing.
If it is rural, check whether you have the full hectare, whether it is common or protected and what your municipality requires.
Ask the house seller for the complete technical documentation, not the catalogue.
Commission the project before paying for the house, so you know what needs to change and how much it costs.
Do not put anything in place without a permit. In the countryside, the risk never expires.

If you have not bought yet, what you need is a feasibility study. And if you are already sure about the land, in Building a house: what to look at before you start and what it really costs we explain the whole process. For any questions, write to us from the contact page with the plot's cadastral reference.