Aprobo inc. - Decibel 3 - SoundSeal on a Light Floor Structure


		DECIBEL3 SoundSeal on a Light Floor Structure

Older Light Floor Structure

Impact
Sound

Airborne
Sound

Example 1: Levels of Impact Sound and Muffling of Airborne Sound

We tested typical older loft ceiling beams (loft ceiling beams with subfloor, tongued and grooved timber with sawed face and sawdust) where the impact sound level, as usual, was very high coupled with the well known low frequency problems.
Since the demands on a solution are great we chose to use the SoundSeal structure with double layers of DECIBEL3 and, in this specific project, a 50 mm's trowelling.

Result:

The result shows a fundamental condition with an impact sound level of L'n,w+C 50-3150 = 67 dB (L'n,w = 64 dB).
After the measures with the SoundSeal structure with double DECIBEL3 were taken, L'n,w+C 50-3150 = 56 dB (L'n,w = 50 dB), was obtained, i.e. an improvement of approx. 11 dB (L'n,w = 14 dB).
The fundamental condition for the muffling of the airborne sound R'w+C 50-3150 was approx. 46 dB and it was improved to 60 dB, i.e. an improvement of approx. 14 dB.

Modern Light Structure

By building new modern structures of a light design these may be constructed in a way that the acoustic fundamental readings become much better than what we are used to in old structures.
As always, one has to find a solution that is effective technically speaking and also financially reasonable.
This is often difficult to obtain.

We have taken part in a SBUF project that Skanska Teknik in Malmoe has been responsible for. The project was based on finding the most effective solution on airborne sound muffling and level of impact sound combined with a competitive product and installation price.
Our contribution consisted of the SoundSeal structure comprising the DECIBEL3 mat with 30 mm's gypsum screeding from TM Progress. Please, consult us for further information about the project. The results are presented below.

Impact Sound

Airborne
Sound

Example with DECIBEL3 + 30 mm's Gypsum Screeding

The structure was organised as follows:

Product	mm's
TM Gypsum Screeding	30
DECIBEL3	10
Particle Board V313	22
Kerto laminated timber beam 45x300x600	300
Mineral Wool Insulation	300
Acoustic Profile s400	25
Gypsum	13
Gypsum	13

Result:

First of all it should be mentioned that the support base per se is good acoustically speaking. The results are laboratory readings.
The starting point for the structure was an impact sound level of Lw +CI 50-2500 = 58 dB and Rw + C50-3150 = 57 dB
The total result for the SoundSeal structure was very successful. We arrived at an impact sound level Lw +CI 50-2500 = 47 dB and Rw + C50-3150 = 65 dB. The SoundSeal structure proved to be very effective and competitive.

The obtained results have theoretically shown that gypsum screeding has proved to be somewhat better (1-2 dB) in comparison with a cement based trowelling. Further evaluation, on site measuring and also future comparisons will be accounted for on our web page. However, there are parameters for cementbased trowelling as well as gypsum screeding in the data base of BASTIAN.

Airborne Sound

Example: Muffling of Airborne Sound DECIBEL3 + 13 mm's Gypsum Floor Board

Even if it is better to use DECIBEL3 in the SoundSeal structure the height of the floor could be a critical factor and one is therefore forced to compromise. That is the reason to why we show an example of a project where the height of the finished floor was a critical factor, which lead to our choosing a 13 mm's gypsum floor board on top of one layer of DECIBEL3.

We had to find a compromise that involved an acceptable improvement of
the muffling of the airborne sound in the frequency midrange.
In this specific case the structure involved approx. 120 mm's concrete with approx. 30 mm's trowelling, a form 150 mm's woodwool and under that 30 mm's plaster. The structure showed the following improvement of the muffling of the airborne sound:

Result:

The original muffling in the structure showed a muffling of the airborne sound (R'w + C 50-3150 Hz) equivalent to 47 dB. The improvement with DECIBEL3 and 13 mm's gypsum added was 5 dB, to 52 dB.
This means that we have moved from not passing sound insulation class D to passing class C in an effective way according to former BBR requirements.
Even if the solution could be made more effective an acceptable compromise was achieved rather simply in this case.

Summary:

The DECIBEL3 mat is a very effective key to solving acoustic problems in light as well as beam and slab floors. DECIBEL3 may be combined with different sheet materials, but generally it is recommended that the mat is used, in single or double layers, as an integrated part in the SoundSeal structure.

For customized calculations on optional constructions we refer to the calculation programme BASTIAN, where the parameters for different constructions are in the database. If you do not have access to this programme, please contact us so we may help you performing the desired calculations.

DECIBEL3 Combined with Sheet Material

DECIBEL3 may be combined with self-supporting sheet material like e.g. 22 mm's particle boards, 18 mm's plywood, minerit, cementbased particle board or 2x13 mm's gypsum floor boards. Because of the fact that the density on top of the DECIBEL mat is important a sheet material with the highest possible density is primarily recommended. This will help affect the lower frequencies too.

Laying double layers of a sheet material also helps overlapping joints which results in a stronger structure. If there is a tongue-and-groove joint as an option this is the strongest choice. The result with sheet material on top of the DECIBEL mats could in simple way be compared mathematically with the facts we have concerning SoundSeal. By comparing the density of the sheet material with the given readings one can generally speaking draw parallel conclusions.