I must confess that when I confront myself every week to a blank screen and get ready to write my next article for CBN, I see the vertical line flashing on and off staring at me and saying “Well I am ready, what about you?”
I normally nod my head and reply “Yes just give me a minute” and I star wondering what subject is sufficiently interesting for the majority of readers, I select the subject, perform a bit of research, carry out a bit of hard work and voilâ the article is completed.
This works fine most of the time, although there are occasions when it doesn’t. Last week was one of those occasions, despite the fact that the subject was selected from the week before: Soundproofing vertical partition walls (Part I) I ended that particular article with much more information to be said the following week, or so I thought, but when I stared that following week and the blinking vertical line on the blank screen in front of me spited out …”Well am ready…” I had very little information to put down. On my subsequent investigation I found very little or no relevant information, nothing occurred to me and what was even worse my mind refused to provide the blank screen any data although and nothing whatsoever materialized so I had to opt to write on a different subject.
In these occasions I identify myself with the actor of the film by Stanley Kubrick “The Shinning” where Jack Nicholson interpret the life of the writer with a wife and young son who accepts the job of an off-season caretaker at an isolated hotel. The son is able to see things in the future and past and is able to visualize ghosts in the hotel. Soon after moving in and a freezing winter storm leaves the family snowed in the hotel. The father becomes unstable from the pressure of finishing his book and attempts to murder his wife and son with an axe.
Well do not fear this week the bad spirits are gone and I am able to finish off the final part of: Soundproofing vertical partition walls.
As you will remember we finished off the article recommending how to sound insulate a single partition wall, so we will proceed on how to insulate a cavity wall or a double wall.
Its effectiveness is based not on the total mass, but in the properties of a mass-spring-mass
(Wall-air-wall where the air acts as a spring between the two leaves). Therefore, it is essential that the construction element has a cavity between the two parts and no contact between the two leaves are allowed, or the properties of sound insulation are lost and then the only improvement for sound insulation is left to its mass and as we have seen is very low in efficiency. The importance of this type of solution is to create a double wall which is an improvement in qualitative insulation, but this is only possible if there is a gap between the two leaves. The greater the distance between the two leaves, the better the acoustic performance of this construction solution in the high frequencies.
This solution works even better if an absorbent elastic material in fitted in the gap. Its effect is to reduce the resonances in the cavity so the more elastic this material is the better it will work. It is important to cover the entire surface of the wall, but is not required to cover entire thickness between the two walls.
It is advisable to that when materials of the two leaves are alike, to have different thickness or density for each leave to prevent sound with the same frequency wave band to coincide and to accumulate.
It is essential to avoid acoustic bridges. There should be no connections between the two leaves and when they connect, for instance as they stand on a concrete floor slab they are set on an elastic strip. The transmission of sound between the perimeters of vertical elements should also be avoided by using flexible material.
The effect that openings have on sound insulation.
The overall insulation of a building depends almost exclusively on the insulation provided by its weakest member.
Gaps can be caused by badly fitted leaves and their frames which leads to spaces which can transmit noise. Whenever you can use certified carpentry types A1, A2, A3.
Errors on the initial design.
The roller shutter box it’s an inevitable cause of acoustic bridging. Therefore, from an acoustic point of view is recommended to protect or use a soundproofing element to insulate the interior of the shutter box.
Sound insulation control
The experience of other European countries indicates that there is a close correlation between the habit of taking measurements and improving the quality and comfort in the home.
The methodology and form of implementation of measures to characterize the acoustics of a building are standardized by the UNE 74-040 "Measurement of sound insulation in buildings and building elements ", of which Part 4 concerns directly with the" Insulation in situ of airborne sound. " It is advisable that tests are done by an accredited laboratory in the application of the relevant standard.
If we require performing an acoustic control of a group of flats we should select a sample sufficiently representative.
Well the article is finally finished…and everyone is safe at home, for this week anyway!!!