NRA France: Nouvelle Réglementation Acoustique — Complete English Guide

La Nouvelle Réglementation Acoustique (NRA) — the New Acoustic Regulation — is France's mandatory framework for acoustic performance in residential buildings. Established by the arrêté du 30 juin 1999 relatif aux caractéristiques acoustiques des bâtiments d'habitation (decree of 30 June 1999 relating to the acoustic characteristics of residential buildings), it has governed acoustic requirements for all new residential construction in France since 1 January 2000.

The NRA is often confusing for non-French acoustic professionals because it uses metrics that differ slightly from both the UK Approved Document E framework and the German DIN 4109 system. Most significantly, France chose DnT,A (A-weighted single-number quantity) as its primary airborne insulation metric — rather than DnT,w (ISO 717-1 reference curve) used in Germany and the UK — based on research showing that DnT,A better characterizes insulation performance against real French traffic and urban noise spectra.

This guide provides a complete English-language reference for every requirement in the NRA, the measurement methods required for compliance verification, and a comparison with other European regulatory frameworks.

Legal Basis and Scope

The Arrêté du 30 Juin 1999

The NRA is not a standards document in the ISO/DIN sense — it is a ministerial decree (arrêté) published in the Journal officiel de la République française. It is directly legally binding law, not a voluntary standard referenced by law. The arrêté specifies:

1. The types of buildings covered (all new residential buildings requiring a building permit)
2. The acoustic performance criteria for internal partitions, floors, facades, and technical equipment noise
3. The measurement methods to be used for compliance verification
4. The sampling requirements for post-construction measurement programs
5. The operator (developer/builder) obligations for remediation of non-compliant units

Buildings Covered

The NRA applies to:

• New residential buildings (maisons individuelles and immeubles collectifs d'habitation) for which the building permit was submitted on or after 1 January 2000
• Major renovations that constitute a change of use to residential from another function
• Extensions to existing residential buildings that create new dwellings

Buildings Not Covered

• Non-residential buildings (offices, schools, hospitals) — these are covered by separate sectoral regulations
• Single-family detached houses (maisons individuelles) are covered by a separate version of the arrêté with slightly different requirements
• Temporary accommodation (camping, mobile homes)

Part 1: Airborne Sound Insulation Requirements (Between Dwellings)

Primary Metric: DnT,A

The NRA uses DnT,A as its primary metric for internal airborne sound insulation. DnT,A is calculated from the field-measured level difference DnT per ISO 16283-1, with A-frequency weighting applied to the octave-band curve before computing the single number:

DnT,A = 10 log₁₀(Σ 10^(Li/10) / Σ 10^(Li−DnT,i)/10)

Where the sum is over the octave bands with A-weighting applied to each band. In practice, DnT,A is typically 1–3 dB lower than DnT,w for typical construction because A-weighting emphasizes the frequency range where typical partitions perform worst (low to mid frequencies) relative to the ISO 717-1 reference curve.

Requirements for Residential Buildings

Between dwellings in the same building (logements superposés ou accolés):

This single 53 dB minimum applies to all separating elements between dwellings, regardless of orientation (horizontal walls, vertical floors, diagonal situations in split-level buildings). There is no distinction between bedroom-to-bedroom and living room-to-living room separations as in some other standards.

Between dwelling and corridor/staircase (circulation commune):

Between dwelling and areas with noisy equipment:

Part 2: Impact Sound Insulation Requirements

The impact sound metric in the NRA is L'nT,w, the normalized impact sound pressure level measured in the field per ISO 16283-2 and expressed as the single-number quantity per ISO 717-2. Lower values indicate better performance.

The NRA requirement of L'nT,w ≤ 58 dB is more stringent than UK Approved Document E (≤ 62 dB) but less stringent than DIN 4109:2018 (≤ 53 dB for German residential). It reflects the typical performance achievable with French reinforced concrete slab construction with a floating screed or tile on resilient mat.

Part 3: Facade Sound Insulation Requirements

Primary Metric: DnT,A,tr

For facade assessment, the NRA uses DnT,A,tr — the A-weighted level difference with the Ctr spectrum adaptation term applied. The Ctr term (traffic noise spectrum) heavily weights the low-frequency performance of the facade assembly, which is most relevant to road and rail traffic noise.

Site Classification by Outdoor Noise Level

The NRA classifies building sites by the outdoor ambient noise level, expressed as Lac (the A-weighted equivalent continuous level during the day from the dominant transport source):

The site class must be determined by noise measurement at the building facade before or during design. The Préfecture (regional authority) publishes noise maps for major transport infrastructure under the Environmental Noise Directive that can be used as a starting point, but facade-specific measurements are required for buildings in higher noise classes.

The higher requirement for Class IV sites (DnT,A,tr ≥ 50 dB) is extremely demanding and typically requires:

• Triple-glazed windows or laminated double-glazed units with thick laminate interlayers
• Sealed facade construction with no trickle vents
• Mechanically ventilated rooms (positive air pressure inlet silencers)
• Heavyweight wall construction with no lightweight cladding panels in frequency ranges critical to traffic noise

Part 4: Technical Equipment Noise Requirements

One of the most distinctive features of the NRA is its explicit requirements for noise from technical building equipment (équipements techniques du bâtiment). Most European acoustic regulations focus on structural sound insulation and leave equipment noise to separate mechanical engineering standards. The NRA addresses it directly.

Requirements for Equipment Noise in Dwellings

The maximum A-weighted level from building equipment measured in a furnished dwelling:

Equipment covered includes: heating and hot water systems, ventilation systems (VMC — Ventilation Mécanique Contrôlée), elevators, hydraulic systems (water supply, drainage), waste chutes, and parking equipment.

The 30 dBA bedroom requirement is among the most stringent equipment noise requirements in any European national standard. It requires careful acoustic design of:

• VMC fans (mechanical ventilation, mandatory in French residential buildings): low-speed operation, flexible connections, vibration-isolated mounting
• Heating boilers: wall-hung or floor-standing boilers must be vibration-isolated from the structure and remotely located from bedrooms
• Domestic hot water systems: circulation pump selection and mounting
• Elevator equipment: gearless drives preferred; machine room isolation for older installations

Measurement Method for Equipment Noise

Equipment noise is measured per NF S31-057 (French standard for measurement of airborne sound from building services) in the dwelling, with the equipment operating at normal design conditions, with the dwelling otherwise unoccupied. Background noise must be at least 10 dB below the equipment noise at each measurement frequency.

Compliance Verification: Post-Construction Measurement Program

Mandatory Sampling

The NRA requires post-construction field measurements by an accredited laboratory. For apartment buildings:

• Airborne insulation: minimum 5% of the total number of measurements corresponding to party walls, with a minimum of 5 measurements and a maximum of 20
• Impact insulation: minimum 3 measurements in different floor-ceiling assemblies
• Facade insulation: minimum 3 measurements in different facade orientations or compositions
• Equipment noise: at least 3 measurements, covering each major equipment type

Consequences of Non-Compliance

When field measurements identify non-compliant units or assemblies, the developer is obligated to:

1. Investigate the cause of non-compliance (design deficiency vs. workmanship error)
2. Implement remedial measures
3. Commission repeat measurements to confirm remediation
4. Report findings to the building control authority (Direction Départementale des Territoires)

The NRA and French Construction Practice

Reinforced Concrete Flat Slab Construction

French apartment buildings are predominantly constructed with béton armé (reinforced concrete) frames with infill masonry walls or concrete block walls. A typical separating wall in French residential construction:

• 200 mm reinforced concrete wall: Rw ≈ 54–56 dB, DnT,A ≈ 50–54 dB in field
• 200 mm aerated concrete block (200 kg/m³), double-leafed with 30 mm gap: DnT,A ≈ 52–55 dB
• Double-skin gypsum board partition with 100 mm MW infill: DnT,A ≈ 52–56 dB

Ventilation System Challenges

The mandatory VMC (single-flux VMC or double-flux VMC with heat recovery) in French residential buildings creates significant equipment noise challenges. The VMC fan must provide sufficient airflow at the design conditions specified in Arrêté du 24 mars 1982 while remaining below the 30 dBA bedroom equipment noise limit. This is achievable with well-selected low-noise fans, acoustic silencers in distribution ducts, and careful duct sizing to minimize flow-generated noise. It is one of the most common NRA non-compliance issues in practice.

NRA vs. Other European Standards: Comparison

France's NRA is broadly comparable to DIN 4109 in its airborne requirements (when the metric difference is accounted for) but imposes the strictest equipment noise requirements of any of the three frameworks. The UK ADE minimum of DnT,w 45 dB is lower than both the NRA and DIN 4109, which partly explains the prevalence of party wall complaints in UK multi-family residential.

What's Next: NRA and RE2020

France's RE2020 (Réglementation Environnementale 2020), which took effect for new constructions in 2022, primarily addresses energy and carbon performance. It does not revise the acoustic requirements of the NRA. However, the shift toward timber-frame and low-carbon construction under RE2020 creates new acoustic challenges: lightweight timber structures perform less well against the NRA's 53 dB DnT,A requirement than traditional concrete construction, requiring additional detailing investment in acoustic isolation.

A revision of the NRA acoustic framework to address these construction evolution challenges is under discussion in the French technical community, but as of 2024, the 1999 arrêté remains the applicable regulation.

Integration with AcousPlan

AcousPlan's Sound Insulation Calculator includes NRA compliance checking with DnT,A, DnT,A,tr, and L'nT,w metrics. Select France as the regulatory framework and the system applies the NRA site-class facade requirements based on the entered outdoor noise level. Party wall and floor compliance is assessed against the 53 dB DnT,A and 58 dB L'nT,w limits from the arrêté du 30 juin 1999.

All calculations are advisory. NRA compliance requires post-construction field measurements by a COFRAC-accredited laboratory.