Impact Noise and Sound Insulation of the Interfloor Slab

Impact noise passing from the upper apartment to the lower one through the slab is one of the most frequent conflicts in a condominium. The matter operates on two distinct levels: on one hand the passive acoustic requirements of buildings, set by the DPCM of 5 December 1997, which concern the construction characteristics of the slab; on the other the limits of normal tolerability of nuisances under Article 844 of the Italian Civil Code, which protect the person suffering the disturbance. These are two different tests, with different premises and consequences, which must not be confused.

The passive acoustic requirements of the DPCM of 5 December 1997

The DPCM of 5 December 1997 sets the passive acoustic requirements of buildings, meaning the performance that horizontal and vertical partitions must guarantee to limit noise transmission. For impact noise of slabs the decree sets a normalised impact sound level index, which in residential buildings must not exceed the prescribed value. These are construction requirements, applying to new buildings and, according to the prevailing interpretation, also to renovation works involving the rebuilding, even partial, of slabs or partitions.

When they apply in renovations

The DPCM provisions must be applied also in the case of renovation of existing buildings when the work involves the rebuilding, even partial, of technological systems or of horizontal or vertical partitions, such as slabs and dividing walls, or the subdivision of real estate units inside the building. Anyone who redoes the flooring and substrate of their apartment, or subdivides a unit, must therefore take into account the acoustic performance of the slab, not only its appearance.

• The DPCM of 5 December 1997 sets passive acoustic requirements, including the slab impact noise level.
• The requirements apply to new buildings and to renovations that rebuild slabs or partitions.
• A slab that fails the requirements may amount to a construction defect.
• Noise nuisances are assessed separately, under Article 844 of the Italian Civil Code.

Nuisances and Article 844

Distinct from the construction requirements is the regime of nuisances. Article 844 of the Italian Civil Code prohibits nuisances, including noise, that exceed normal tolerability, having regard to the conditions of the location. An owner disturbed by impact noise can act to stop or reduce the noise when it exceeds the tolerability threshold, regardless of whether the slab meets the DPCM parameters. Proof of failure to meet the passive acoustic requirements does not coincide with proof of an intolerable nuisance: they are separate assessments.

Poor insulation as a defect of the work

When sound insulation is poorly done in a new or renovated building, case law tends to treat it as a serious defect of the work, with the protections provided on the liability of the builder and contractor. In this case the owner or the condominium can seek recourse against the builder for the acoustic inadequacy of the slab. This is, however, a relationship between client and builder, distinct from the conflict between neighbours over everyday noise.

Who pays for upgrading the slab

Work to improve the acoustic performance of the slab follows the rules on ownership. If the noise results from the upper owner redoing the flooring without an adequate insulating substrate, the burden of remedying it falls on whoever carried out the works. If instead the work concerns the common structure of the slab, Article 1125 becomes applicable again, with the structural cost split in half between the two neighbouring owners. The technical classification of the point where the insulation acts is therefore decisive for the allocation too.

The role of the manager and the regulation

The condominium manager has no direct powers in noise conflicts between neighbours, which remain relations between private parties, but can recall compliance with the condominium regulation, which often governs times and manner of use. When the noise comes from work on common parts, however, the matter enters their competence and can be brought to the meeting. Recording reports, sound-level surveys and communications helps handle the case in an orderly way and prevent litigation.

To collect reports, keep acoustic surveys and communications and track works on slabs and common parts, orderly management software simplifies the work. With AmministraPro you can manage reports and claims, archive technical documentation and communicate with owners in a traceable way: the features are described on the /funzioni page and the plans on the /prezzi page.