Let's leave in peace (with proper sound insulation)

Worldwide, 130 million of people are exposed to noise levels above 65 dB, while another 300 million live in uncomfortable noise levels (55-65 dB), according to a study cited in the magazine Ciudadano.

Hopefully this allegation is about to be changed in Spain.

As I mentioned in past commentaries on CBN, the new Spanish Building Regulation “El Código Técnico de la Edificación” does establish new concepts to tackle this enormous and complicated problem.

Before we embarked ourselves into technical details let’s establish some noises and their correspondent measurements in Decibels so that we have some points of reference.   

• Normal conversation (at a distance of 3-5'): 60dB
  
• City Traffic: 85dB
  
• Train whistle at 500', Truck Traffic: 90dB
  
• Level at which sustained exposure may result in hearing loss: 90 - 95dB
  
• Sandblasting, Loud Rock Concert: 115dB
  
• Pain begins: 125dB
  
• Even short term exposure can cause permanent damage: 140dB
  
• Death of hearing tissue: 180dB
  
• Loudest sound possible: 194dB 

Having set up those points of reference let’s try to understand what the Spanish legislator have tried to achieve.

In its preamble the Royal Decree 1371/2007, dated 19 de October of 1997 declares: 

“The acoustic contamination suffered by citizens in buildings, is one of the major obstacles to enable us to enjoy an adequate and dignify home. Noise is also a source of illness and irritation to citizens. Public Authorities must establish adequate mechanism to facilitate the use of buildings so that its occupancy should be done free of acoustic contamination.”

With this objective in mind the 38/1999 law of 5th of November does set up rules and procedures to guarantee the wellbeing of people and protection of the environment.

 

Full of good intentions.

As we can see the preamble is full of good intentions, but do the regulations stand up to this expectation?

Well, as we shall see later, this regulation does indeed attempt that buildings do have adequate acoustics insulation to reduce the transmission of impact and airborne sound as well as to limit sound reverberation in public spaces.

One major difference that we architects have found with this recent regulation is that all sound insulation required and then specified must be proven “in situ”.  With the old noise regulation architects only had to demonstrate that his intended solutions would work under laboratory conditions. Obviously the standard insulation that can be achieved under laboratory conditions is far less strict than under a normal building site.

Let me explain it. Let us suppose that we have calculated that a party wall require a sound insulation of 45 Decibels. Well, we know that a solid brick wall 12,5cm wide, rendered and then plastered both sides under laboratory condition would attain 45 Decibels sound insulation. Under the old regulation we dint need to do nothing else than to specify the characteristics of that wall on our project. But is it so in a real situation? Well, it depends. We may well have a window, or maybe we have wire ducting that dramatically reduce sound insulation especially when we have power sockets on exactly both sides of the party wall. As most people know sound insulation works as water in a container, we may have an extremely good sound insulation shell but if we have a hole, all sound insulation produced by that shell is worthless, noise will penetrate the shell through the hole propagating itself through the air.

So it is imperative that property developers carry out sound insulation tests when properties are finished, because as we all know, we may have a very impeccable sound insulation specifications but building site conditions is a very different thing.

The new regulations clearly affirm that sound insulation specified on a project must comply also under real circumstances. This consideration by itself is sufficient to improved significantly sound insulation in our homes.

Another important change in the application of this regulation is that before the 5th of November of 1999, architects would design the same sound insulation anywhere in Spain, independently if our building would be situated in the centre of the nosiest street in the middle of Madrid or in the middle of a neighbourhood surrounded by golf course.

 

Every major town in Spain must have a noise map.

The responsibility to elaborate a noise map falls upon town halls as it is defined by the 2002/49/CE (2007-2008) directive in its 1st Phase for larger cities such as Valencia Alicante Murcia etc. Hopefully we will have noise maps for the rest of towns later on.

So now we have a noise map indicating noise level of every street. Architects must make his starting point for his calculations on the Decibels indicated for that building on that particular street on the noise map, so now we design under real world conditions and therefore should obtain a more real realistic result.

Independently of what I have indicated above, this new regulations have increased required sound insulation for similar conditions on party walls, impact sound on floors between different dwellings etc. So not only have changed the methodology for checking the sound insulation that we have calculated but standards have increased as well.

Another profound difference on the application of sound insulation is the section dealing with impact sound.

With the old regulation it would suffice to have a normal floor slab to comply with sound insulation for impact sound. However, now all floors between dwellings must have its floor finish on a floating screed on an elastic mat on top of the floor slab. This floating screed must be independent of all partitions and fixed structural elements so that little sound is transmitted to the floor below or adjacent.

This solution is also applied to common spaces such common staircases, common entrances, halls etc.

There are strict applications of sound insulation to installations services.

Bath tubs and shower trays must be fixed onto rubber blocks, and their top edges must be wrapped up with rubber seals so that there are no direct contact between sanitary equipment and any other construction element and therefore avoiding any transmission of water impact noise to floors below.

All water pipes must be suspended from anti-vibratory brackets. Lifts must have its railings installed in such a manner so that no vibration is transmitted to any floor slab or walls. Its engine and all other movable parts have to be installed so that no vibration is transmitted to any construction element.

I sincerely belief that all these new regulations, will undoubtedly improve significantly sound insulation in our homes, making them much more comfortably and pleasant to reside in.