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RENOVATION

Renovation is a quite usual procedure in Europe [25]. There may be quite a few reasons to go for it. To start with, older buildings usually feature a higher potential occupation ratio per ground square meter than the one allowed by normal recent constructions. More to the point, it helps the urban planners to keep a homogeneous urban appearance. Last but not least, it helps save time if the walls and floors (and sometimes even the roof) are kept; administratively speaking, it may also speed up things, for when the envelope of the building is kept, one often will solely require permission for fitting out the building spaces instead of a full building permit. In the case of performance halls, there often is a sentimental and historical value associated with the building that makes it hard to forget [26].

On the negative side, it is not uncommon to lack some suitable space to route the ducts and pipes through. Quite often, the walls and floors have inadequate acoustic performance and must be upgraded using plasterboard and mineral wool stud-mounted elements that will reduce the available floor dimensions and height. Last but not least, the available volume is not always suitable for the wished-for performances [27].

In such a kind of project it is necessary first to perform a diagnosis of the existing building in order to find out how it is built and where the sensible points are. Each specialty will have to perform its own diagnosis. One should remember that a structural diagnosis usually can be a bit destructive, as the structural engineer will typically cut through floors and walls in order to assess their composition, so the acoustician must make his measurements before this is done.

Note: There is a strong need for coordination between the interested parties, as depending on the planned sketch of the future rooms inside the building, some zones will be more sensible than others. More to the point, everybody must be aware of each other’s needs.

In addition, one must be particularly aware of the safety requirements applicable: Whenever derogation is delivered, it will certainly entail so-called mitigating measures that will probably be costly in terms of investment or extra personnel (cf. Section 6.10.8).

The diagnosis through measurements will feature:

  • • Sound insulation measurements between rooms when the walls are kept. Note: This measurement will help assess the potential flanking transmission by those walls, as well as the potential sound insulation of those rooms.
  • • Sound insulation measurements and impact sound measurements between rooms at different floors. Note: This measurement will help assess the potential sound insulation between floors.
  • • If applicable, vibration measurements on the floors or walls. Note: This will help assess the eventual noise generated by vibrations (e.g., from rail lines nearby) and vibration levels inside the building.
  • • An acoustic diagnosis of the site will be performed as per a regular new construction project (i.e., assessing the sound level values on the site and finding out what the potential noise sources around are, as well as the potentially sensible zones around). Note: Do keep in mind that usually a renovation project will entail some demolition (now politically correctly described as unbuilding) prior to the actual construction work. Under the nice words one can already hear the concrete breakers hammering away, so one had better have a good look at the location of the nearest neighbors, especially those who are structurally linked to the building. It will probably be necessary to explain to the neighbors the basics of the project and point out that while some phases of the work will be noisy, they will be kept to a minimum of duration and their time schedule will be adapted while appropriate noise reduction measures will be implemented.

It must be stressed that the diagnosis will constitute the testimony to the acoustic performance of the building prior to any work. It is not only a basis for the acoustic studies (from which predictive computations will be elaborated), but it is also often a compulsory step to be able to ultimately prove that the initial acoustic performances of the building have not been compromised [25].

In the particular case of historical buildings, things can get quite complicated, as usually the fagades and even the roofs must be preserved. In some cases it is even necessary to preserve some interior spaces (e.g., because of paintings on the walls or ceilings). Under such circumstances the acoustic objectives must be adjusted on a case-by-case basis, and specific solutions must be elaborated (e.g., introducing intermediate spaces around in order to prevent direct transmission to other spaces of interest, or working on the other side of the partition or floor using such doublings as a floating floor, a plasterboard ceiling, or half wall, with mineral wool in the void).

A special mention must be made regarding performance halls: Those are usually considered a historical landmark, and the end user may wish to preserve or even improve much more than the sound insulation characteristics (though it is not always the case, please see Section 6.10.7). This means that specific room acoustic measurements must be carried out in order to explain the physical phenomena that are behind the acoustic characteristics, and then questions must be addressed to the users to know for sure whether they actually want them to be kept as such. Only after that will it be possible to prescribe the relevant constructive solutions.

 
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