Aprobo inc. - Decibel 2 - Floating Parquet


		DECIBEL2 Floating Parquet

By combining the DECIBEL2 mat with floating parquet flooring (also laminate) a considerable reduction of the impact and drum sound levels is achieved. Tests have indicated that the DECIBEL2 mat only gives a slight/marginal parquet resonance -a phenomenon that normally is frequent with other types of floating floor structures.

The combination of DECIBEL2 and floating parquet has been installed for over 15 years and there are a great many satisfied customers.

Impact Sound

HD/F and Solid Concrete beams

The acoustical effects are more or less the same independently of if it is a standard crude beam construction or a HD/F type. However, the HD/F type requires greater thickness to match solid concrete beams acoustically. HD/F structures are often covered with a topping or float filler. On this construction an optional flooring is laid. Today's requirements on a floor structure combined with a surface layer have airborne sound muffling and impact sound level in view.

To improve the sound muffling it is possible to increase the thickness of the HD/F element alternatively solid floor structure or to pour an extra topping. This is, however, connected to great costs and increased height of the finished floor. As a comparison a theoretical estimation of the muffling of the impact sound with an extra topping of 15-20 mm's would result in 2-3 dB vertical improvement.

Example 1: Impact Sound Muffling

HD/F elements (195 mm's) topped with 50 mm's trowelling. This floor construction handles approx. L'nw=75 dB of impact sound muffling (poorer than the requirements for class D). The adjacent diagram illustrates the improvement With DECIBEL2 combined with parquet.

Result:

There was an improvement reaching L'nw= 53dB
i.e. an improvement of 22dB

Example 2: Impact Sound Improvement

The measuring was performed on a standard slab without finishes with DECIBEL2 combined with laminate flooring respectively lamel parquet.
(NT ACOU 034 ΔLw)

Result:

Laminate: ΔLw= 20 dB
Lamel: ΔLw= 18 dB

For customized calculations on optional constructions we refer to the calculation programme BASTIAN, where the paramaters 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.

Summary:

Using DECIBEL2 as an underlay on a concrete slab floor (slab without finishes alternatively HDF) will be an effective way to improve/muffle impact sound at a low cost and a minimum increase of the height of the finished floor.

		Airborne Sound

In general terms it is possible to say that underlay products impair the muffling of airborne sound when installed under floating parquet flooring.

The DECIBEL2 mat has proven to eliminate this problem, which must be considered unique. The mat also provides an improvement of the muffling of the airborne sound at the higher frequencies as shown in the example below.

HDF / Concrete Slab without Finishes

Example 1: Muffling of Airborne Sound with DECIBEL2

HDF structures with the corresponding construction to the impact sound example above. We install the DECIBEL2 mat under lamel parquet and we can see the improvement vertically and an unaltered reading horizontally. As a reference it could be mentioned that the floor structure showed muffling of airborne sound equal to 56 dB (vertical) and 53dB (horizontal)(R'w+C50-3150Hz).

Result:

DECIBEL2 combined with the lamel parquet resulted in 58 dB (an increase with 2 dB vertically was created due to pipes that were installed wrongly before) and 53 dB (horizontally). This is a very good result, and it shows that the parquet resonance is minimal and that the muffling of airborne sound is improved at the higher frequencies.

Parquet Resonance

Parquet resonance is created, as mentioned earlier, when a floating parquet flooring produces resonance with the backing. The problem is magnified if an equal flooring is to be found in an adjacent room and when the floor is large relatively to the partition area to the neighbour's. However, it is a common problem everywhere where a parquet flooring is installed floating on a concrete floor structure. Underlay mats do generally increase the problem with parquet resonance, but we have found proof for the fact that the DECIBEL2 mat results in a minimal parquet resonance. All in all it is a very good result -especially since it occurs in combination with the rest of the improvement (acoustically speaking), e.g. impact sound, drum sound etc.

Example: A Comparison of Parquet Resonance

The measurement was performed on 195 mm HDF structure with trowelling. The measurement was registered partly on the floor structure and partly with the DECIBEL2 mat under floating lamel parquet.

For comparison we show a measurement performed by Chalmers that shows typical parquet resonance when the parquet is installed on a standard underlay respectively the floor structure without flooring.

Result:

Here the marginal parquet resonance is clear and the improvement of the muffling of the airborne sound is approx. 500-3150 Hz, approx. 4dB.

Summary:

With DECIBEL2 the parquet resonance is marginal and any possible minimal deterioration is compensated by the fact that the muffling of the airborne sound is improved at higher frequencies. Altogether, an unaltered muffling of the airborne sound is achieved instead of a considerable deterioration, which is common with other types of underlay mats.

		Drum Sound

Although drum sound is not yet included in any standard sound insulation class (standardization is under development), it does not make it less important. On the contrary, this sound is often experienced as disturbing. The problem has increased during later years as the number of installed hard flooring has increased. The problem is very often the greatest in public premises, offices, schools etc. Here the drum sound clearly contributes to a deteriorated acoustical environment. Today, there are underlay products on the market that do create a certain impact sound improvement, but at the same time they will increase the drum sound problems.

The DECIBEL2 mat has a very good effect on the drum sound -especially on the thinner (and more critical) parquet flooring. Since there is no way to pin point a certain frequency as "extra disturbing" it is impossible to state a single elementary reading for successful drum sound muffling. Here we would like to illustrate a critical range of frequencies where a lot of "noise" is created that could be experienced as disturbing. We also wish to show how different products affect the drum sound in a room.

Example: A Comparative Drum Sound Measurement

Shown below is a comparison between laminate flooring, laminate flooring + cell foam underlay and laminate plus DECIBEL2. We have indicated the critical range of frequencies where drum sound generally is experienced as disturbing. It is possible to say that the thinner the parquet is the greater the drum sound is. Another important factor is the nature of the drum sound. - How is the sound perceived?

Result:

An interesting observation is that the cell foam underlay does not manage to muffle the drum sound when the critical range is reached. There is even deterioration in comparison with laminate flooring installed without any underlay. DECIBEL2 shows a considerable reduction over a wide range of frequencies.


	Without Decibel2		With Decibel2

Personal
Estimation

It is possible to show acoustical readings of different kinds with a number of tests (standardized or not). It is impossible to cover all acoustical varieties to 100% that will be the case when using different flooring, structures and tolerances. We are constantly looking for new test methods and we perform new tests with the DECIBEL mats in order to create a solid basis for our arguments. In spite of all this work it is always the personal estimation of the result that really counts. "Does it sound good?", The answer must be "Yes", to have a satisfied customer. DECIBEL2 has yielded many satisfied customers over the years, customers that keep coming back because the chosen combination of flooring with DECIBEL2 has been to their liking.