Height of buildings: the actual width of the road counts, not that foreseen by the urban plan

Building permit and “virtual” road widening

The matter arises from the challenge, by a neighbor, of a building permit issued by the Municipality for the construction of a residential building made up of two buildings. Permission contested because the art. 61 of the Technical Implementation Regulations (NTA) of the General Urban Plan (PUG) imposed a ratio of 1/1 between the height of the new building and the width of the facing street, a ratio that had not been respected.

While the actual state saw a road just five meters wide, in fact, the building project approved by the Municipality calculated the maximum height based on the theoretical expanded section envisaged by the PUG. In this way, the building rose on the front to heights between 13.15 and 13.50 metres, far exceeding the limit of 10.50 meters which would have been derived by applying the real ratio on the existing roadway. The Puglia TAR had accepted the neighbour’s appeal, a decision then challenged by the Municipality. The judges of Palazzo Spada found the organization wrong.

The current situation and forecasts

The Council of State rejected the Municipality’s argument, fully confirming the orientation of the TAR judges. The judges of Palazzo Spada reiterated that the needs of territorial planning, healthiness, hygiene and harmonious insertion of the volumes into the road context require that the width of the road be identified in its real and effective consistency at the time of evaluating the building permit application.

The deduction is not permitted based on a future and possible urban transformation, especially when, as in the case in question, the provision for widening the roadway has remained totally unimplemented for 18 years. The presence of an urban planning constraint or a road destination imprinted by the master plan does not change the material situation: as long as the urbanization works do not physically modify the road surface, the virtual road parameter has no direct building relevance for the calculation of the heights of private buildings.

The correct qualification of technical volume

A further focal point of the decision concerns the attempt to justify the height of the road front – raised by more than three meters compared to the line of the roof slab – qualifying this structure as a “technical volume” intended to house a photovoltaic system. The Supreme Court recalled the parameters to be applied for the definition of absentable technical volume:

• it must be an artefact of limited volumetric consistency;
• must be devoid of any functional autonomy, even if only potential or residential;
• there must be a strict technical necessity and the absolute impossibility of placing the technological systems inside the main building.

In all cases, as established some time ago by the Council of State itself, “Qualification requires proof of the strict necessity of the volume, the absence of alternatives and the impossibility of placing the systems in the body of the main building” (most recently ruling 7558/2024).

In the situation considered, raising the perimeter wall more than three meters beyond the line was deemed not to meet the indispensability requirement. The judges highlighted how the photovoltaic system could be allocated with different technical methods that had a decidedly less impact on the overall shape of the property, confirming the illegitimacy of the addition. Furthermore, the TAR itself had found that raising the perimeter wall by more than three meters was functional to the preparation of a further roofing structure, without revealing the strict technical indispensability of this solution.

The rules for the correctness of projects in reference to heights and technical volumes

The following table summarizes the application criteria confirmed by the Council of State for the correct determination of building and road parameters.