Sound absorption of floors
ITALIAN REGULATIONS >>
LAW 447/95 AND PRIME MINISTERIAL DECREE 5/12/97 – “Determination of the passive acoustic requirements of buildings”
- “The framework law on noise pollution” – Law no. 447 dated 26 October 1995 – which sets out the fundamental principles on the subject of protection from noise produced by the external environment and the residential environment, pursuant to Article 117 of the constitution, was published on 30 October 1995 in the ordinary supplement to Official Gazette No. 254.
Article 3 of said law establishes the competencies of the State and in particular the task of establishing, through decree of the President of the Council of Ministers (Prime Minister), the acoustic requirements of sound sources inside buildings and the passive acoustic requirements of those buildings and their components when working. The Prime Ministerial Decree “Determination of the passive acoustic requirements of buildings” dated 5 December 1997 was published on 22 December 1997 in Official Gazette No. 297 in compliance with the provisions.
THE PRIME MINISTERIAL DECREE OF 5/12/97 IN BRIEF >>
In enforcement of Article 3, section 1), letter e) of Law 447/95, the decree determines the acoustic requirements of the sound sources inside the buildings, the passive acoustic requirements of the buildings and their components when working with the aim of reducing human exposure to noise.
The acoustic requirements of sound sources other than those indicated above are determined by other enforceable provisions of Law 447/95.
Article 2 – Definitions
For the enforcement purposes of the decree, the environments are divided into the categories indicated in table A.
In section 2) of this article, both horizontal and vertical partitions are defined “components” of buildings.
Section 3) defines lifts, sewer systems, bathrooms, toilets and tap systems as services in intermittent operation.
Section 4) defines heating, ventilation and air conditioning systems as continuously operating services.
Section 5) refers you to Attachment A of the decree for the definition of the reference noise volumes.
|Cat.||Type of building|
|A||Buildings for residential use or similar|
|B||Buildings for office use and similar|
|C||Buildings used as hotels, boarding houses and similar activities|
|D||Buildings used as hospitals, clinics, nursing homes and similar|
|E||Buildings used for scholastic activities at all levels and similar|
|F||Buildings used for recreation or worship or similar|
|G||Buildings used for commercial activities or similar|
as per Tab. A
|2. A, C||50||63|
|4. B, F, G||50||55|
|The greater the R’w: the better the performance||The greater the ∆Ln,w and more
reduced the L’n,w: the better the performance
Article 3 – Limit values
In order to reduce human exposure to noise, Table B indicates the maximum magnitude limits that determine the passive acoustic requirements of components and internal noise sources of the buildings, which are defined in Attachment A to the Prime Ministerial Decree.
The reference magnitudes shown in Table B, which characterize acoustic requirements of the buildings and are to be determined with measurements when working, are the following:
- reverberation time (T);
- apparent sound insulation power of the separation elements between rooms (R’).
This magnitude represents the sound insulation power of the separation elements between habitations and also takes into account the lateral transmissions (dB).
- Standardized surface sound absorption (D2m,n,T,w).
- The normalized impact level (L’nw). From L’nw values, expressed as a function of frequency (thirds of an octave), you go to the L’nw index of the normalized floor impact level making use of a special normalized procedure. The evaluation index thus allows you to characterize the floor’s insulation impact noise properties with a single number.
- LAS max is the equivalent weighted continuous sound pressure level A, with slow time constant, produced by the intermittent operation services.
- LA eq is the maximum weighted sound pressure level A, produced by continuous operation services.
Article 4 – Entry into force
Since the Prime Ministerial Decree came into force sixty days after its publication in Official Gazette No. 297 dated 22 December 1997, it became effective from 20 February 1998.
IMPACT NOISE: FLOORS >>
Impact noise on floors can be caused by:
- percussion (falling objects, footsteps, etc.)
- vibrations (machines)
- friction (dragging furniture).
Because of the rigid continuity of structures, the transmission of impact noise reaches parts of the building distant from the sound source itself, unlike airborne noise.
The most efficient solution both in terms of acoustic and economic results consists in the use of the so-called “floating floor”, the purpose of which is to obtain a flooring free from rigid connections with other structures. This total desolidarization is obtained by placing a suitable elastic material between the flooring, side walls and load bearing floor. The quality of the construction of the floating floor is very important, since even small rigid connections considerably reduce the sound absorption performance of the system.
The Italian regulations and Prime Ministerial Decree 5/12/97: Scope of application (Art. 1): in enforcement of article 3 of Law 447/95, the decree establishes the acoustic requirements of sound sources and the passive requirements of buildings in order to reduce human exposure to noise.
Classification of rooms by purpose (art. 2)
A – Buildings for residential use or similar
B – Buildings for office accommodation and similar
C – Buildings used as hotels, boarding houses and similar activities
D – Buildings used as hospitals, clinics, nursing homes and similar
E – Buildings used for scholastic activities at all levels and similar
F – Buildings used for recreation or worship or similar
G – Buildings used for commercial activities or similar
|Limit values(art. 3)|
|cat. from tab. A||L’n,w|
|4.||B, F, G||65|
|The lower the L’n.w, the better the performance|