The notion of useful volumes and surfaces: the two jurisprudential orientations
Jurisprudence records two orientations regarding the notion of volumes and surfaces useful for the purposes of verifying the prerequisites provided for by the law in question.
A first orientation incorporates a concept of useful surface in a broad and finalistic sense, not limited to closed spaces or interventions capable of causing an increase in the urban planning load, but rather considering the impact of the intervention on the original layout of the territory and, therefore, the suitability of the new surface, whatever its destination, to permanently modify the constrained original conformation of the territory. Therefore, the concept also extends to those surfaces that are not normally considered relevant according to urban planning and building regulations (1), noting that, for the purposes of ascertaining landscape conformity, the impact of the intervention on the original layout of the territory must be verified for any walkable building work that can be exploited for any use (2).
In fact, the assumption appears correct according to which the notion of “useful surface”, for landscape purposes, is not limited only to closed spaces or interventions capable of causing an increase in the urban planning load, but instead considering the impact of the intervention on the original layout of the territory and, therefore, the suitability of the new surface, whatever its destination, to permanently modify the constrained original conformation of the territory. The legal qualifications relevant from an urban planning and construction perspective are not automatically transferable when it comes to qualifying the works from a landscape perspective. Each regulatory construct must, in fact, be observed through the ‘lens’ of its specific disciplinary context (for this same reason, for example, the so-called ‘technical’ volumes, although irrelevant from an urban-building perspective, are instead subject to the prohibition on issuing landscape authorization in amnesty, which protects the different interest in the visual perception of the artefacts, completely regardless of their intended use).
The conclusion, moreover, is supported by the same letter of the art. 167 of the Code, which refers – disjunctively – to the creation of “useful surfaces or volumes“, considering that in landscape matters the “non-habitability” of the surface does not at all allow us to exclude its “utility” character for the purposes of art. 167, paragraph 4, letter a): in this matter, the notion of useful volume (as well as useful surface area) must be interpreted in the sense of any building work that can be walked on and/or that can be exploited for any use, given that the concept of utility has a different meaning in the legislation on landscape protection compared to the regulation construction(3).
A second orientation, however, highlights that the concepts of volume and useful surface area, referred to in the landscape context but not defined by the Code, must be traced back to the technical-legal definitions deducible from the Consolidated Building Act (4) and, therefore:
- the volume of the buildings, expressed in cubic meters empty for full, is made up of the sum of the surface delimited by the external perimeter of the various floors by the relative effective heights measured from floor to floor of the attic above (5);
- the useful surface area (SU) coincides – in a nutshell – with the habitable area (floor surface area of the accommodation measured net of walls, pillars, partitions, door openings, door and window spaces, any internal stairs, loggias and balconies).
According to this orientation, attributing the same meaning to the same notion used in the Code and in the Consolidated Construction Law is an option which, as well as adhering to the lexical data, appears to be the most reasonable. In fact, hypothesizing, on the contrary, and in order to extend the scope of the prohibition on posthumous landscape compatibility, that the Code of Cultural Heritage and the Consolidated Law on Construction contain two different meanings – in addition to contrasting with the principles of coherence, unity and systematicity of the legal system – would result in an unjustified disparity in treatment to the detriment of those who request the amnesty of illegal works in restricted areas, compared to those who exercise the same right in free areas.
Therefore, the content that administrative jurisprudence attributes to the identical notion in construction matters must be assigned to the notion of useful surface area, as a disqualifying element for the posthumous amnesty of an abusive intervention; with it, the creation of a walkable surface has always been identified, usually not exposed to the elements, which can be the object of a residential/residential/commercial use, or in any case suitable for the carrying out of human activities, not necessarily private, of various nature, i.e. with content almost never (or rarely) pre-determined “a priori”.
The further characterizing connotation is given by the autonomous usability of the created space, which is valorised, in itself, as a single good, not necessarily, nor always, connected to others, in order to be enjoyed, also because it is normally subject, as mentioned, to a multiplicity of possible uses.
A recent concrete case
Adhering to the second orientation, the TAR Campania, Salerno, sec. I, in the sentence. 24 October 2025, n. 1721, considered that the creation of new walkable surfaces could not be considered in the face of a minor earth movement intervention which had not really changed the state of the places but had simply better defined the area concerned, on the basis of the already existing conformation, with the aim of facilitating agricultural activities.
In particular, from the comparison of the orthophotos relating to the state of the places, depicting the overview of the entire complex, no significant and relevant creation of surfaces emerged between the original situation and the one following the intervention, with a “not dissimilar” configuration between the before and after, considering that the latter had, in short, eliminated any disorderly vegetation present and given a more regular shape to the already existing slopes, generated by agricultural processing activities; similarly, no new volumes had been created, considering that the operations had involved the removal of earth and not the addition of materials.
Consequently, the judges considered the negative opinion of the Superintendence illegitimate.
Notes
(1) Council of State, sec. VI, sentence. 11 October 2024, n. 8150.
(2) Council of State, sec. VI, sentence. 15 November 2024, n. 9169.
(3) Council of State, sec. IV, sentence. 13 June 2023, n. 5807; section II, sentence. November 28, 2023, n. 10189.
(4) Council of State, sec. VI, sentence. 31 March 2014, n. 1512 and sent. 13 May 2016, n. 1945; sent. 6 April 2020, n. 2250.
(5) Council of State, sec. VI, sentence. 1 December 2014, n. 5932; sent. 16 June 2021, n. 4658.
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