Construction tolerances are not a passport to expand properties. The 2% margin must be calculated in relation to the project of the new intervention to be carried out and not in reference to the overall size of the property.
In essence, construction tolerances can never justify the construction of extensions nor can the total volume of the building be used to remedy an abuse in an area where no works were planned. The Council of State clarified the principle once and for all with sentence 4283/2026. And in any case there are no possibilities for amnesty if the property is located in an area protected by landscape restrictions. In these cases, the size of the abuse does not matter: even a single additional square meter triggers a total block.
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The stairwell and the 2% question
The case addressed in the sentence concerns a property in the historic center of Verona, zone A and subject to landscape restrictions. In 2014, the owner had requested the application of the construction site tolerance for a stairwell on the seventh floor terrace, demolished and rebuilt with significantly larger dimensions than the pre-existing one: from 2.90 by 1.40 meters with an average height of 1.70 metres, to 3.85 by 2 meters with a height of 2.32 metres, and with a change in the roofing from sloping to flat.
The Municipality denied both the tolerance and, subsequently, the assessment of landscape compatibility. The owner appealed to the TAR, which rejected it. Sentence confirmed by the Council of State.
What is the 2% calculated on: the controversial point
The technical issue of the appeal concerned the basis for calculating the tolerance percentage. The owner argued that the 2% should be calculated on the entire property unit (apartment and terrace), which would have made the increase in volume compatible with the legal threshold. The Council of State excludes this reading: the art. 34 paragraph 2-ter Presidential Decree 380/2001 in the text applicable at the time, referred to 2% “of the design measures” for each single real estate unit, and this means that the parameter must be the volume already absent from the building permit relating to the intervention – in the specific case, the stairwell as envisaged in the 1996 renovation – and not the overall volume of the unit or building.
The principle, recalled by the judges with reference to three precedents of the same section (Cons. Stato, sec. II, 15 March 2024 n. 2510; sec. II, 3 June 2024, n. 4975; sec. II, 3 November 2023 n. 9520), is clear: the constructive tolerance only covers the minimal discrepancies that emerged in the execution phase of an already approved project, it can never be extended to works that constitute a new intervention with respect to the title or different in type, materials and utility.
In the case in question, the 1996 permit did not provide for any expansion of the stairwell: its reconstruction with larger dimensions and volume is therefore a new work, not a tolerance, and as such can at most be the subject of a request for amnesty pursuant to art. 36 Presidential Decree 380/2001, if the conditions exist, not building site tolerance.
How the discipline of tolerances has changed
The Council of State specifies that the rules subsequent to 2011, although not applicable to the case for temporal reasons, confirm the same principle: tolerance always concerns the same intervention already approved, never a further work. On the constitutional level, Constitutional Court no. is also referred to. 24/2022, which qualifies the regulation of construction tolerances as a fundamental rule of economic-social reform, uniformly binding throughout the national territory, including the Regions with special statute – and for this reason the municipal building regulation (in the case of Verona, art. 46, approved with council resolution no. 20/2012) can only be interpreted in compliance with the state law.
The landscape restriction closes the amnesty
Since this is a restricted area, the increase in volume also fundamentally excludes the possibility of ascertaining landscape compatibility. The art. 167 of Legislative Decree 42/2004 does not allow amnesty for works that have led to the creation of useful surfaces or volumes, or the increase of those legitimately created, a case which the Council of State also refers to letter a), point 1-ter, of the art. 181 of the same decree.
The double track, building and landscape, therefore produces a convergent outcome: neither tolerance nor amnesty, in either location.
What emerges for technical practice
The ruling offers a clear operational criterion for those who must evaluate a similar intervention: the construction site tolerance is always verified by comparing the work carried out with the specific measures provided for in the authorization document which approved it, not with the overall volume of the real estate unit nor with that of the building.
When the work carried out does not correspond to any title, the ordinary amnesty pursuant to art. 36 remains the only viable route, with the further limitation, for listed properties, of the exclusion of the landscape amnesty in the presence of increases in volume.
The evolution of the legislation, table
We see in this table how the legislation regarding construction tolerances has evolved:
|
Norm |
Reference |
Content |
|---|---|---|
|
Art. 34, paragraph 2-ter, Presidential Decree 380/2001 |
Introduced by art. 5 DL 70/2011 |
2% tolerance on design measurements for each single property unit, referring to height, separations, volume or covered surface area |
|
Art. 34-bis Presidential Decree 380/2001 |
DL 76/2020 |
It moves the regulation of construction tolerances (paragraph 1) and introduces “executive” tolerances (paragraph 2): geometric irregularities, modifications of finishes, different placement of systems – excluded for properties restricted pursuant to Legislative Decree 42/2004 |
|
Art. 34-bis, amendments |
DL 69/2024 |
Expands the allowed tolerance percentages, differentiating them based on the size of the real estate unit |
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