Campo das Cebolas
Acoustic insulation and sound absorption in the heart of Lisbon

Acoustic comfort and tradition: the added value of Diasen

The acoustic insulation in the Campo das Cebolas underground car parking was necessary due to the location of the structure. The building is located in one of Lisbon’s most popular historical areas between the Avenue Infante Dom Henrique and the Bairro de Alfama, a place where not only different epochs of Lisbon’s history meet, but also many locals and tourists. The project, which finds an element of redevelopment in the underground parking area, aims to enhance the extraordinary mix of history and modernity in the heart of Lisbon.

Architect: João Luís Carrilho da Graça
Time of realization: 5 weeks
Location: Lisbon, Portugal
Intervention: Acoustic insulation and sound absorption 

Sound absorption

NRC: 0,60

Thanks to its excellent sound wave absorption value, the material guarantees maximum performance



Macroporous structure that guarantees sound absorption performance and acts as a hygrometric lung for excess moisture

Fire reaction


Class A1 according to UNI EN ISO 13501-1. No flame generation and no smoke emission


Learn more about the technical aspects of Diasen sound insulation and sound absorption solutions

The technical pillars of intervention

Acoustic insulation and sound absorption were achieved with Diathonite Acoustix cork-based thermo-acoustic plaster. The solution was applied in the more than 5000 sqm of ceilings of the underground car park built in Lisbon, very close to the famous Alfama district, on the banks of the river Tejo. The project involved the spray application of 3 cm of Diathonite Acoustix on the ceilings of the structure, laid in two layers of 1.5 cm each. Polites 140 structural reinforcement mesh was applied between the first and second layers.

In order to combine the acoustic requirement with an aesthetic appearance centred on an almost smooth finish, Argatherm Acoustix acoustic skim coat was used, which, thanks to its microporosity, allows the system to perform acoustically while maintaining a fine and uniform grain size.

Used products

The following solution cycle was applied to ensure sound insulation and sound absorption performance in the underground car parking area. Discover the products more in detail.

Diathonite Acustix application methods

Discover how quick and easy it is to apply our Diathonite Acoustix and Diathonite Acoustix+ solution on any type of surface. The cork-based plaster, being sprayed with a plastering machine, adapts to any geometry and shape, guaranteeing sound insulation and sound absorption performance. It also prevents and eliminates material and geometric thermal bridges

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Acoustic insulation of city centre car parking

The need to a good acoustic insulation in car parking areas in city centres is one of the most difficult challenges for planners and engineers. Vehicle traffic is today the most significant factor in noise pollution in cities, and car parking are inevitably connected with the presence of a large number of people circulating in a well-defined area. However, parking areas are conceptually connected with the structure to which they refer, as well as the place where they are located. In fact, their contribution to noise pollution is different from that of car parks along public city streets. In particular, underground parking constitutes the greatest noise pollution problem associated with central heating and cooling systems in buildings. The noise emission associated with parking a car can be divided into several phases: the access routes to the parking spaces; the duration of the search for a free parking space; and the opening and closing of the doors of the car.
It is therefore essential for the planner to have a concrete solution in hand that prevents all these factors already at the preliminary design stage. Avoiding or counteracting the propagation of sound waves of noise produced during the entire search and parking phase of vehicles wandering around within a confined space is the key to being able to satisfy the acoustic comfort of the people living above or near to these areas, improving the living comfort in the rooms adjacent to the parking area.

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