Design Process
What is land occupation?
Following the article what is land buildability, today we will explore another crucial concept in urban planning regulations: what land occupation is.
There is a tendency to confuse it with buildability, since both refer to the square meters we are permitted to build on a specific plot. Therefore, we will begin by describing in detail the land occupation factor, so that we can later understand its difference from buildability.
What is land occupation?
So, let us begin: What is land occupation?
Land occupation is defined as the percentage of a plot that can be occupied by the building in the projection of a structure onto the land.
The purpose of this regulation is to guarantee a certain proportion of the plot for trees and landscaping, which is why it also makes sense to establish an occupation limit for elements without above-ground volume: basements, swimming pools, paved areas, etc.
Explained in other words, land occupation is what we would see if we took an aerial photograph of the plot; the surface occupied by the building in relation to the land, without taking into account the total number of floors.
The regulation of occupation in urban planning
The creation and limitation of this possibility to build more or less on a plot stems from the evolution of urban planning regulations in our country. At the Spanish level, in 1956 the ‘Land Regime and Urban Planning Law’ was approved, which represents the first law to jointly address the regulation of land and urban planning.
In fact, all subsequent legislation has maintained the different forms of urban planning action and the differentiation of land into legal regimes.
This regulation is based on the analysis of a highly complex reality such as urban territory, aiming to design and create concepts and regulations that shape the future of this situation towards the established objectives.
In the case of occupation, its emergence stems from the limited structure of urban occupation we have in the territory. Initially it serves as an analytical element, but later patterns are generated and occupation criteria are established according to each zone.
In fact, occupation is limited according to municipal urban planning regulations, that is, directly by the town council, through what is called ‘maximum land occupation’.
In any case, this maximum percentage will largely depend on the type of land in question, which we recently explained in the article Types of land: urban, developable, non-developable.
Classifying any plot into 3 land typologies helps us structure the territory, thus establishing the logic we want to apply, for example, to the future of a municipality: which areas we intend to stabilize or dilute (urban land), which areas we allow to continue growing and densifying or begin to grow (developable land), and which areas we want to preserve due to their natural value (non-developable land).
Urban land is that where building is permitted, whether in a more or less densified manner. Specifically, the land most subject to maximum occupation regulations is that of Barcelona, since there is a desire not to further densify a highly populated city limited by the sea and mountains when it comes to growing in surface area.
On the other hand, developable land is that which is transitioning towards the possibility of building on it, which is regulated by permitting or not its conversion into urban land, but also by establishing from the outset the maximum occupation that will be permitted.
Finally, in the case of non-developable land, there is no limitation on maximum land occupation as building is not permitted on it, with the intention of protecting rural land.
What is the difference between land occupation and buildability?
Perhaps the best way to understand what land occupation is is through its comparison with the term buildability, a concept that refers to urban development potential.
Both terms are susceptible to being confused given that both buildability and land occupation refer to a quantity of square meters in relation to the total surface area of the plot.
However, in the case of buildability, it refers to the total buildable square meters, including all constructed floors, while occupation determines the percentage of the plot’s surface area that we can occupy with our dwelling, regardless of the number of floors we intend to build.
To see the difference between buildability and land occupation more clearly, we will analyze an example of land buildability and occupation:
Calculation of land occupation and buildability
Let us suppose we have a plot of 1,000 square meters with a buildability of 0.5 m2 of ceiling/m2 of land and an occupation of 25%.
What do these values mean?
In this case, having a buildability of 0.5 m2 of ceiling/m2 of land, we can build half of the total surface area of the plot. That is, for a plot of 1,000 m2 we can build a house of 500 m2 in total, adding the surface area of each of the floors.
As we have an occupation of 25%, this means that we can only occupy 25% of the total 1,000 m2 of land, therefore, we must plan a dwelling that does not occupy more than 250 m2 on the ground (25% of 1,000 m2).
From here we can build 2 floors until we exhaust the 500 m2 of maximum built surface area, that is, until we exhaust the buildability. Depending on what the maximum number of floors set by the regulations is, we can consider building 2 floors.
Calculation criteria
Once we go into detail about what land occupation is, we realize that a series of calculation criteria must be established for elements that generate confusion: this is the case with courtyards and cantilevered structures.
Courtyards
A courtyard is an architectural resource that allows light, radiation, and ventilation to enter the interior of a building. At the firm we use the courtyard resource extensively in our projects, not only as an additional solar capture strategy, but as genuine passive systems for naturally ventilating our dwellings, either through pre-heating the air we must introduce for renewal or through generating natural cross-ventilation that cools the environment in summer.
So the question is, do we count the courtyard in the calculation of occupation? And in buildability? There are two different criteria, which in any case will always need to be confirmed with the applicable municipal regulations, but in general, depending on whether it is a case of detached building on a plot typical of a garden city or street alignment typical of the urban center.
In the case of a detached dwelling, the space occupied by the courtyard does not count in terms of buildability, but it does count for land occupation. However, in the case of a building between party walls aligned with the street, courtyards count for both buildability and occupation.
Cantilevered structures
Cantilevered structures respond to the definition of a part of the building that, on a floor above the ground floor (GF), protrudes beyond the limits defined by the GF and is susceptible to being occupied or inhabited. We distinguish between two types of cantilevered structures: open and closed cantilevered structures.
Examples of closed cantilevered structures include bay windows, galleries, or even overhangs and porches.
These cantilevered structures may or may not count within occupation and buildability, and it is necessary to assess in each case the municipal regulations not only whether these are included, but also whether they must respect the same distance from the plot boundaries as the rest of the building.
Swimming pools
In many municipal regulations, swimming pools count as part of or in the total occupation, although in many cases the distances from plot boundaries can be reduced.