The decree governing the design, execution and testing of all constructions in Italy. It sets the safety levels required of structures — new and existing — with a performance-based limit-state approach, and regulates actions, materials, geotechnics and seismic design in a single text.
It applies to all constructions — buildings, bridges, geotechnical works, structures in concrete, steel, timber, masonry — across the national territory, both for new works and for the assessment of and interventions on existing buildings. It concerns structural designers, works directors, testers, contractors and producers of structural materials.
NTC 2018 organises the entire construction cycle into twelve chapters: principles and expected performance, actions (permanent, variable, seismic, accidental), design rules for each structural material — reinforced concrete, steel, timber, masonry, composite structures — geotechnics, testing and existing buildings. The framework is performance-based: the code sets the safety levels and the performance to be guaranteed, leaving the designer responsible for the choices made to achieve them.
Safety verification adopts the semi-probabilistic limit-state method: actions are amplified and resistances reduced by partial factors, and the structure is verified both against collapse (Ultimate Limit States) and in everyday service conditions (Serviceability Limit States: deflections, cracking, vibrations).
The design seismic action is built from the hazard of the individual site (national reference grid) combined with the nominal life of the works and their use class — four of them, not three: from Class I, structures with only occasional presence of people, to Class IV, structures with important public or strategic functions, by way of the ordinary Class II and the crowded Class III (§2.4.2) — and with local conditions: subsoil category and topography. From these come the response spectra used in design. The structure's dissipative capacity enters the design through the behaviour factor, tied to the structural type and to the chosen ductility class.
For the existing stock the code introduces the safety assessment — mandatory in defined cases, such as changes of use or significant structural interventions — and three categories of intervention: local repair, affecting single elements; improvement, which raises safety without necessarily reaching new-build levels; and full upgrading, which reaches them. The path runs through knowledge of the building: survey, investigations and knowledge levels that condition the confidence factors allowed in calculations.
Every material or product for structural use must be identified, qualified — through CE marking where a harmonised standard exists, or through national procedures — and accepted on site by the Works Director, with tests and documentation. It is the bridge between a material's datasheet and its legitimacy for structural use.
The full text of the decree is published in the Official Gazette and can be consulted free of charge at the official source indicated on this sheet.
Where this rule shows up in past architect qualification exams — study the rule, not just the theme.
Yes: chapter 8 is dedicated to existing buildings. It defines when the safety assessment is mandatory and classifies interventions into local repair, improvement and full upgrading, with increasing requirements.
The nominal life is the number of years for which the structure, with ordinary maintenance, must retain its design performance. The use class describes the consequences of an interruption or a collapse, and there are four classes (§2.4.2): Class I gathers structures with only occasional presence of people, Class II ordinary ones, Class III crowded ones or those with hazardous contents, Class IV those with important public or strategic functions. Together they determine the reference period for the seismic action.
For structural works governed by the NTC, static testing is the mandatory final verification, entrusted to a professional independent from design and works direction in the cases provided by law, certifying conformity with the design and the standards.
Improvement increases the existing structural safety without the obligation to reach the levels required for new buildings; full upgrading reaches them. The choice depends on the type of intervention: some (e.g. adding storeys) require full upgrading.
No: they coexist. The NTC is the binding national code; the Eurocodes are referenced for what is not covered and may be used within the limits set by the NTC itself.
CE marking qualifies the product, but chapter 11 still requires identification and on-site acceptance by the Works Director, with the controls and documentation required for each material.
The decree is published in Ordinary Supplement no. 8 to Official Gazette no. 42 of 20 February 2018, freely available on the Official Gazette website (link on this sheet).