Why the check precedes the design
Establishing that a property is regular is a precondition for three distinct operations. None of the three can dispense with it.
It is a precondition for building work, because a consent cannot be obtained over an unlawful existing building without first regularising what is not lawful. A consent cannot graft onto an existing condition that is not lawful.
It is a precondition for a sale, because non conformity affects marketability and the declarations required in the deed. Non conformity affects marketability and the declarations made on completion.
It is a precondition for access to incentives and reliefs, whose regime belongs to tax law but whose premise is the planning regularity of the property being worked on. Their regime belongs to tax law but shares the same premise.
The concept of stato legittimo
Article 9-bis of the consolidated building code defines the stato legittimo of a property, its lawful planning status, and identifies the evidence establishing it. The provision was amended by Decree Law 69 of 2024, converted by Law 105 of 2024 and known as the Salva Casa decree, which intervened substantially in this area.
The approach is documentary. Lawful status is demonstrated through the consent that authorised the construction or subsequently legitimised it, together with the later consents authorising works on the same building, with specific provision for cases where the original consent cannot be traced or the property was built before consent became mandatory.
Reconstructing lawful status has become a professional service in its own right, with its own methodology of documentary research in municipal, land registry and other administrative archives. The subject, the documents that may be relied on and how the technical report is drawn up are covered in the dedicated page.
What the work actually involves
Reconstructing lawful status is archive work before it is survey work, and the sources to interrogate are of different kinds. The sources to search are of different kinds.
| Source | What it yields |
|---|---|
| Municipal building archive | Consents issued, approved drawings, any enforcement measures |
| Land registry archive | Plans filed over time, with the dates of variation |
| Heritage authority archive | Authorisations relating to listed properties |
| Regional seismic office | Filings and authorisations on structural matters |
| Deeds and title documentation | Planning declarations made on previous transfers |
Two cautions on this material. A land registry plan is not a building consent and its consistency does not establish planning lawfulness: the two checks are distinct and both must be carried out. The absence of a consent from the archive does not mean it never existed, because municipal archives have gaps, particularly for earlier decades.
The final comparison is between what the archives document as approved and what the survey measures as existing. It is from that difference, read element by element, that the list of non conformities to be classified emerges.
Differences that do not amount to non conformity
Not everything departing from the approved design is a breach. Article 34-bis of the code governs tolleranze costruttive, construction tolerances, meaning departures of limited extent which do not constitute a violation and can be certified by a qualified professional.
The Salva Casa decree also introduced article 34-ter, identifying particular cases of partial non conformity removed from the ordinary sanctions regime. The cases identified follow a regime of their own.
The practical significance of these two mechanisms is considerable. A substantial share of the irregularities emerging from a survey of the existing condition falls within them, and distinguishing what is tolerable from what requires regularisation changes the route and the cost of the operation radically.
Use classification
One aspect intertwined with compliance is the classification of use. The code identifies functional categories and governs changes of use, distinguishing material changes from those that are not and establishing when a change requires a consent.
This area was also affected by the 2024 amendments. Economically the change has a direct effect: it bears on the development contribution, because moving to a more onerous functional category triggers payment of the difference. It is the point at which the compliance check meets the budget of the operation.
What skipping the check produces
Three recurring outcomes follow from having skipped this stage. All three surface when it is too late to remedy them.
An unapprovable design is the first. The municipality identifies the non conformity of the existing building during review and suspends, and regularisation becomes an unplanned precondition with unforeseen timescales and costs.
Work carried out on an unlawful basis is the second, producing a situation in which the new is added to the old without regularising anything, complicating later regularisation. The new is added to an unverified existing condition.
A blocked property transaction is the third, surfacing at completion or during a lender's review, when the time available to act is at its shortest. It surfaces at completion or during a lender's review.
A caution on the regional dimension
This branch is where the local dimension weighs most. The Salva Casa decree intervened in an area of shared competence and its reception has not been uniform: some regions have adopted their own rules, and administrative case law continues to define the boundaries of the mechanisms introduced.
None of the guidance in this branch can therefore be applied without checking the regional legislation in force and the municipal building regulation, and without verifying the date on which the source consulted was last updated. The check is an obligatory step.
Note: the legislative references in this page relate to Italy and are current as at the date of publication. This area has been subject to recent amendment with non uniform regional reception: the regional legislation in force and the municipal building regulation should be checked before any operational use.