Impact sound reduction in the lab
To facilitate comparisons of various floor solutions for dampening impact sound, there is a classification system in SP’s guidelines “Stegljudstestade golvbeläggningar” (Impact sound tested floor coverings) (SP Report 2012:47). The impact sound classification is based on the weighed summation value ΔLw, calculated by the SP Technical Research Institute of Sweden from 16 values in the one-third octave band (100–3150 Hz) according to SS-EN ISO 717-2. Buildings with concrete floors and coverings in impact class 7 normally fulfil BBR’s requirements (sound class C).
Granab systems produce ΔLw 29 dB, which fulfils the highest impact sound class 8A. Floors in this class normally fulfil impact sound requirements for sound class A in buildings with heavy concrete floors.
Granab subfloor systems have been tested by the SP Technical Research Institute of Sweden on a reference subfloor of 16 cm concrete according to the Swedish and international standard SS-EN ISO 10140.
The impact sound tests were conducted with 15 mm parquet flooring on flooring paper, Granab’s subflooring of 22 mm chipboard flooring that was glued and screwed to the 7000 system’s steel sections, green Sylodyn® dampening pads and spacer screws in the concrete subfloor. The dampening pads are built in under the steel sections and permit movements in the floor without impact sound being transmitted via the screws to the concrete subfloor. By comparing measured impact sound levels for completed floors with the levels attained for the lab’s concrete subfloor alone, the SP Technical Research Institute of Sweden can present improvement values for the Granab system (ΔLw) that were calculated in the one-third octave band according to ISO 717-2.
The improvement values from the lab can be used for calculating impact sound levels in buildings with other types of concrete subfloors in accordance with SS-EN 12354-2. Values for Granab systems and various concrete subfloors are in the database for the calculation programme BASTIAN. When calculating impact and airborne sound insulation in subfloors between rooms, the programme takes into consideration the effects of areas and room volumes, as well as adjoining structural elements, which allows both simple and cost-effective engineering of a building’s sound insulation. The calculation results have been compared with a large number of values from field measurements and have been shown to conform well to average values. Granab recommends maintaining a 1 dB margin when engineering to acoustic requirements in completed buildings in accordance with SS 25267/-68.
Guidance in the choice of floor coverings and upper flooring on thin concrete subfloors according to SP’s guidelines “Stegljudstestade golvbeläggningar” (Impact sound tested floor coverings) (SP Report 2012:47)
In SP’s appendix, classification is conducted of floor coverings’ impact sound dampening on thin concrete subfloors. The classification is conducted in seven different floor covering classes with descriptions of impact sound dampening for the respective floor covering classes. The highest floor covering class is class 8A, which the Granab systems fulfil by a wide margin. Wooden floors and carpet on a thin elastic mat normally fulfil impact sound class 7, which results in sound class C on the same floor. Weighted impact sound dampening is defined in SS-EN ISO 717-2.
|Floor covering class||∆Lw, dB
||Significance/Application. Floor coverings in the group|
||Can fulfil sound class A between dwellings when they are laid on concrete subfloors.
Floor covering class ∆Lw, dB Significance/Application. Floor coverings in the group
8A 25 – 28 Can fulfil sound class A between dwellings when they are laid on concrete subfloors.
For a full description, please refer to SP’s report (www.sp.se)
Read more about acoustics
Impact and airborne sound insulation
Impact and airborne sound insulation in homes and offices
Impact sound reduction in the lab
Impact and airborne sound reduction System 3000N
Impact and airborne sound reduction System 7000N
Step and airborne noise reduction CLT
Offices and public buildings
Granab subfloor system 3000N
For adjustable heights from 30 to 140 mm, excluding floor covering.
Granab subfloor system 7000N
For adjustable heights from 50 to 420 mm, excluding floor covering.
Granab Subfloor system 8000W
Granab subfloor system 9000N
For adjustable heights from 70 to 420 mm, excluding floor covering.