Insights

Building acoustics: the RRAE, acoustic testing and what is changing in permitting

12 July 2026

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Few building defects generate as many complaints — and complaints as hard to resolve — as noise. Hearing the footsteps of the neighbour upstairs, the lift at night or the street traffic in a poorly insulated bedroom is not merely a nuisance: it is, more often than not, a regulatory failure. Unlike a leak, an acoustic problem is rarely fixed with a one-off repair; once the building is finished, putting it right means demolishing and rebuilding.

At CertiAmb, the acoustic design — the projeto de condicionamento acústico — is developed in coordination with the other engineering disciplines, from the concept stage onwards. In this article we explain the legal framework — the RRAE and the General Noise Regulation —, the requirements by building type, the role of acoustic testing at the permitting and occupancy stages, and what changes with the revision of the RJUE (Regime Jurídico da Urbanização e da Edificação, the urban development legal regime) published in 2026.

Two regulations, two objects: the RGR and the RRAE

Building acoustics in Portugal rests on two complementary statutes:

• The Regulamento Geral do Ruído (RGR, the General Noise Regulation), approved by Decreto-Lei n.º 9/2007, de 17 de janeiro, which deals with environmental noise: it classifies the territory into sensitive zones and mixed zones (a municipal responsibility, exercised through territorial plans and noise maps) and sets exposure limit values — in mixed zones, L_den ≤ 65 dB(A) and L_n ≤ 55 dB(A); in sensitive zones, 55 and 45 dB(A); where no classification exists, 63 and 53 dB(A). It also regulates noisy activities and the annoyance criterion.
• The Regulamento dos Requisitos Acústicos dos Edifícios (RRAE, the Building Acoustic Requirements Regulation), approved by Decreto-Lei n.º 129/2002, de 11 de maio, as amended by Decreto-Lei n.º 96/2008, de 9 de junho, which sets the acoustic performance requirements of the buildings themselves: façade insulation, insulation between units, impact sound, equipment noise and reverberation conditions.

The two regimes are interlinked: it is the zone classification under the RGR that determines the level of façade insulation required by the RRAE, and article 12.º of the RGR makes both the permitting and the occupancy of buildings conditional on compliance with the acoustic requirements. Paragraph 7 of the same article also allows construction in consolidated urban areas that exceed the limit values, provided the façade insulation is reinforced by 3 dB — a frequent situation in Lisbon and in historic centres.

Requirements by building type

The RRAE applies to residential and mixed-use buildings, hotel establishments, commercial and service buildings, schools, hospitals, sports venues, passenger transport stations, and auditoriums and performance halls. For residential and mixed-use buildings — the most common case — the essential requirements (article 5.º) are:

• Façades of bedrooms and living areas: D_2m,nT,w ≥ 33 dB in mixed zones and ≥ 28 dB in sensitive zones (plus 3 dB in the situations covered by paragraph 7 of article 12.º of the RGR);
• Between dwellings: airborne sound insulation D_nT,w ≥ 50 dB; between common circulation areas and dwellings, ≥ 48 dB; between commercial or service premises and dwellings, ≥ 58 dB;
• Impact sound: L'_nT,w ≤ 60 dB in bedrooms and living areas (≤ 50 dB where the emitting space is used for commerce, industry or entertainment);
• Communal building services (lifts, mechanical ventilation, booster pump sets): L_Ar,nT ≤ 32 dB(A) for intermittent operation and ≤ 27 dB(A) for continuous operation.

In hotel establishments, each guest room is treated as a dwelling — a requirement introduced in 2008 that strongly conditions the construction solutions in hospitality. In schools, beyond insulation, reverberation control and sound-absorbent finishes are required in atriums and corridors; in auditoriums and cinemas, article 10.º-A imposes specific reverberation and intelligibility studies and reinforced insulation between rooms. In rehabilitation work in historic areas, where the use and the heritage identity are preserved, there is a 3 dB tolerance on several requirements — a relevant point for anyone rehabilitating older buildings, a subject we develop in our article on the decision between building and buying.

Acoustics in the permitting process: design and certificate of responsibility

The acoustic design is one of the parts of the engineering-discipline project supporting the permit application or the prior notification, under Portaria n.º 71-A/2024 — which identifies the situations in which noise studies and an acoustic assessment are required. Article 3.º of the RRAE lays down its own rules on responsibility:

• the design must be prepared and signed by qualified professionals — engineers holding a specialisation in acoustic engineering from the Ordem dos Engenheiros (the Portuguese engineers' association) or professionals with a qualification in building acoustics recognised by their professional association;
• the professional's declaration takes the form of a termo de responsabilidade (a certificate of responsibility), dispensing with prior review of the design by the municipal services;
• execution on site is assessed under the RJUE, with the site manager and the supervising engineer responsible for ensuring conformity with the design.

This model — compliance declared by the professional, with no prior validation by the municipality — has existed in acoustics since 2008 and anticipated the logic that the Simplex Urbanístico later generalised. The trade-off is clear: responsibility falls entirely on those who design and build, which makes initial technical rigour all the more decisive. That is also why coordination between the architecture and the acoustics should start early: the thickness of a slab, the location of a service riser or the stacking of uses determine the acoustic performance long before any materials are chosen.

Acoustic testing: from construction to occupancy

The RRAE stipulates that verification of compliance is carried out on the basis of acoustic tests, performed in accordance with the applicable standards and under article 12.º of the RGR, read together with its articles 33.º and 34.º. In practice:

• the tests measure in situ the relevant indices — façade insulation, insulation between units, impact sound, equipment noise;
• they must be carried out by accredited bodies or following the methodologies and sampling criteria defined by LNEC (Laboratório Nacional de Engenharia Civil, the national civil engineering laboratory);
• in in-situ assessments an uncertainty factor I of 3 dB applies: a building is deemed compliant if the measured value, corrected by that factor, meets the regulatory limit — a margin that a prudent designer should not use up at the design stage;
• the acoustic assessment forms part of the documents submitted for the occupancy of the building, supporting the accompanying certificate of responsibility.

With the Simplex Urbanístico (Decreto-Lei n.º 10/2024, de 8 de janeiro), occupancy authorisation now rests, as a rule, on the certificates of responsibility signed by the professionals, without a prior municipal inspection. The acoustic assessment has not disappeared — quite the opposite: in a framework where the municipality no longer validates beforehand, a test carried out by a competent body is the objective evidence that protects the developer, the professional and the future occupant. The general framework of these procedures is described in our article on construction permitting in Portugal.

What is about to change: the new RJUE in 2026 and the revision of the RGR on the horizon

Two developments deserve the attention of anyone with projects under way:

• The new RJUE. Decreto-Lei n.º 108/2026, de 29 de maio — the 21st amendment to the RJUE, which also revises the 2024 Simplex, the RGEU (the general urban buildings regulation) and the urban rehabilitation regime — enters into force on 3 August 2026. It reinforces prior notification as the central procedure and deepens the logic of professional accountability. It does not change the technical requirements of the RRAE, but it sharpens the framework in which acoustic compliance is declared — and, with it, the weight of testing as the evidence supporting that declaration.
• Revision of the RGR. The revision of the General Noise Regulation, in force since 2007, has been under preparation within the National Environmental Noise Strategy 2025-2030, promoted by the Portuguese Environment Agency (Agência Portuguesa do Ambiente), which points to updated metrics and management instruments. As at July 2026, the new statute had not yet been published — but anyone designing today should follow this evolution, above all in areas exposed to traffic.

Common mistakes on site — and their consequences

Experience in site supervision and construction management shows that most test failures stem from a small set of mistakes:

• poorly executed floating screeds — interrupted resilient layers, rigid skirting boards or pipework creating impact-sound bridges;
• acoustic bridges in service risers, deep chases and back-to-back electrical boxes in separating walls between dwellings;
• communal equipment (lifts, pumps, HVAC) without anti-vibration mounts or with rigid fixings to the structure;
• window frames and glazing installed with a lower performance than specified in the design, or poor sealing between frame and opening;
• changes during construction — material substitutions, new openings — without revalidation of the acoustic design.

The consequences are not merely technical. Preparing designs or carrying out works in breach of the RRAE constitutes a serious environmental administrative offence under Lei n.º 50/2006; a non-conformity detected in the final test can block the occupancy of the building; and the cost of correcting insulation once the building is finished is a multiple of the cost of getting it right first time. To this is added the reputational and contractual risk towards buyers — who are increasingly attentive to acoustic comfort as a purchasing criterion.

CertiAmb's integrated approach

A building's acoustic performance is decided in the interaction between disciplines: the architecture defines the organisation of the spaces, the structure conditions slabs and supports, the HVAC introduces noise sources and the service networks cross separating elements. Treating acoustics as an annex delivered at the end is a recipe for failed tests. In an integrated approach, acoustic performance is checked at every design decision — and the final tests confirm, rather than surprise.

CertiAmb develops acoustic designs within the overall framework of the engineering disciplines, monitors execution on site and coordinates acoustic testing with accredited bodies, in Lisbon, the Alentejo and the Ribatejo. You can find out more about our team and our method on the About CertiAmb page.

Frequently asked questions

When is an acoustic design mandatory?
Whenever the development covers buildings subject to the RRAE — housing, hotels, commerce and services, schools, hospitals, sports venues, transport stations and auditoriums. It is one of the parts of the engineering-discipline project and must be signed by a professional qualified in building acoustics.

Is acoustic testing mandatory?
Yes. Verification of compliance with the RRAE is carried out on the basis of acoustic tests, performed in accordance with the applicable standards and the LNEC sampling criteria. The acoustic assessment forms part of the documents submitted for the occupancy of the building.

What sound insulation is required between dwellings?
Between separate dwellings, D_nT,w ≥ 50 dB; on the façades of bedrooms and living areas, D_2m,nT,w ≥ 33 dB in mixed zones or 28 dB in sensitive zones; impact sound L'_nT,w ≤ 60 dB.

Did the Simplex Urbanístico do away with the acoustic assessment?
No. It changed the mode of control — occupancy now rests on the certificates of responsibility signed by the professionals, without prior municipal review — but the acoustic assessment and compliance with the RRAE are still required, with greater accountability for those who sign.

What happens if the building does not comply?
Breach of the RRAE constitutes a serious environmental administrative offence (Lei n.º 50/2006), can prevent the occupancy of the building and forces costly corrective work on a finished building, in addition to the risk of disputes with buyers.

Closing notes

Acoustics is one of the disciplines where the difference between a well-coordinated design and box-ticking compliance can be heard — literally — for decades. With the new RJUE reinforcing professional accountability and the revision of the RGR on the horizon, the safe route is the usual one: a rigorous design, supervised execution and tests that confirm the performance. If you have a construction or rehabilitation project in preparation and want to ensure acoustic compliance from the very first sketch, talk to the CertiAmb team.