This article aims to clarify how the constructed area of a building in Barcelona can be calculated, according to different definitions.

When asked how is the constructed area of a building calculated? we have to know that the answer is “It depends on what for”

Since it is not the same if we want to know the built area to justify urban operations than to register or declare a property in the Cadastre.

We are going to see below the different definitions that we can find according to which regulation or body defines it:

According to the R.A.E.

If we search for surface (just surface because there are no results for “built” precision) in the dictionary is word gives us two interesting meanings of the six:

f. Phys. Quantity that expresses the extension of a body in two dimensions, length and width, and whose unit in the international system is the square meter (m2).
f. Geom. Measure of a surface.

These meanings are what is commonly understood by surface, however, to carry out urban operations that involve a little more precision, this parameter must be specified a little more and clarified. For example: what is the difference between the constructed area and the constructed area, is a facility yard counted as a constructed area? Is a staircase counted as a constructed area? Are the balconies counted? And the terraces? What is the difference between built and computable surface?

According to the urban regulations of the General Metropolitan Plan of Barcelona

In the O.M.E. Metropolitan Building Ordinances of the PGM of 1976 article 180, referring to the maximum housing density defines the built surface in this way (logically, this built area, as it refers to the maximum number of dwellings, will only be valid for this purpose):

Article 180 – Maximum number of dwellings

(…)

2. For the purposes of this article, the constructed area of the building is understood to be that included between the exterior enclosures. Semi-closed projecting bodies are included, open projecting bodies are counted as 50 percent of their surface, and light and ventilation patios and basements are excluded.

In Barcelona there is a modification of article 180 (the modification of 2004):

(…)

2. For the purposes of this article, in the areas of the old town and urban densification, the constructed area of the building, in new plant actions, is understood to be that between the exterior enclosures. The patios of lights and ventilation are included and the projecting bodies, the ground floor surface that exceeds the buildable depth, and the basements are excluded. – Note that light patios, etc. are included. These conditions are therefore only valid to obtain the constructed area for the calculation of the maximum number of dwellings –
3. In the rest of the zones, for the calculation of the constructed area of the building, the same criteria will be adopted that establish the urban regulations of the Metropolitan General Plan for the calculation of the buildability.

For urban parameters such as buildability, we will take this definition as valid (including interior patios, excluding balconies, etc.). However, it is confusing, for example, if attics were discounted below a free height of 1.50 m. Common sense and observing other regulations tells us yes.

As we will see later, the definition of the cadastre is more precise since it clarifies that to consider a built surface, the space must have a height greater than 1.50 m.

According to the UN of the General Plan of Zamora

To compare a little further, we have searched online for some other plan that would make a definition of the built surface more independent and not subordinate to another concept, as in the case of Barcelona, to the maximum number of homes.

In article 24, point 2 says:

Constructed area is understood to be the floor of the building per floor delimited by the outer perimeter including all stairs and common elements. It will also include the total surface of the ground of the closed salient bodies, half of the open ones and half of the surface of the entrances – this last sentence is curious, the entrances are counted at 50%, in the cadastre it is it would count at 100% and we believe that the Barcelona urban planning department would also have the same opinion – The floor area in which the free height is less than 1.50 meters is excluded