PROCEEDINGS of the23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, GermanyFloor impact sound insulation of the six-story wood-frame modelbuilding
Atsuo HIRAMITSU1; Ryuta TOMITA2; Susumu HIRAKAWA3; Masayoshi SATO4
1

National Institute for Land and Infrastructure Management, Japan
234Nihon University, Japan

Building Research Institute, JapanJapan 2x4 Home Builders Association, Japan

ABSTRACTIn Japan, the Act for Promotion of Use of Wood in Public Buildings was enforced in 2010. As a result, thenumber of constructions using the timber structure became more popular for the buildings. However, theperformance of the floor impact sound insulation in the timber construction buildings is often concerned asworse than the concrete constructions. In this paper, an experiments were carried out on a newly built sixstory wood-frame building to investigate the performance of the floor impact sound insulation on fivedifferent floors; CLT panel floor, stressed skin panel floor, LVL floor, I-joist floor and chord truss floor. The
result showed that the stressed skins panel floor has the highest performance of heavy-weight floor impact
sound insulation. The paper also reports the sound insulation of separation wall and the vibration performancein the timber construction building, and proposes an improvement plan for the better floor impact andairborne sound insulation performance in the timber construction buildings.
Keywords: Floor impact sound insulation, Wood-frame construction, Cross Laminated Timber

1. INTRODUCTION
In Japan, the Act for Promotion of Use of Wood in Public Buildings. was enforced in 2010. As aresult, the number of constructions using the timber structure became more popular for the buildings.
Thus, consideration is being given to the high-rise building by timber construction.
Currently, the knowledge about the performance of the high-rise timber building is limited. It isbelieved that the sound insulation performance in the high-rise timber building is often concerned as
worse than the concrete construction. However, there is no rigorous report has been published yet.
For this reason, we built a six-story wood-frame model building for assessing the performances ofconstruction, building deformation, living environment, durability and sound insulation.
In the previous studies, we investigated the floor impact sound insulation performance of a woodframed model building for experiments which had four-story, and we tried to improve the floor impact
sound insulation in reference (1). For the CLT building, we reported the measurement results of floor
impact sound insulation and sound insulation of separation wall in Cross Laminated Timber building
in references (2, 3 and 4).
In this paper, the experiments were carried out on a newly built six-story wood-frame building toinvestigate the performance of the floor impact sound insulation on five different separation floors;
CLT panel floor, stressed skin panel floor, LVL floor, I-joist floor and chord truss floor. Moreover,this paper also reports the sound insulation of the separation wall and the floor vibration performancein the model building.
1

hiramitsu-a92ta@mlit.go.jp
tomita.ryuta@nihon-u.ac.jp
3
sh@kenken.go.jp
4m-satou@2x4assoc.or.jp
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2.

SIX-STORY WOOD-FRAME MODEL BUILDING

Fig. 1 shows an outside view of the six-story wood-frame model building. It is 7,280 mm wide,5,005 mm deep and 17,309 mm height. Each of the five floors (1 st floor to 5th floor) has almost thesame arrangement of living space, and there were two living areas (dwelling units, 3,640 mm wideand 2,502.5 mm deep) on each floor except for the 6th floor. The 6th floor has one living area (dwellingunits, 3,640 mm wide and 2,502.5 mm deep).
Fig. 2 shows a cross-sectional view of the six-story wood-frame model building. The five different
separating floors exist on each floor; 2nd floor: CLT panel floor, 3rd floor: stressed skin panel floor, 4thfloor: LVL floor, 5 th floor: I-joist floor and 6th floor: chord truss floor is shown.

6th floor
chord truss floor

5th floor
I-joist floor

4th floor
LVL floor

3rd floor
stressed skin panel floor
2nd floor
CLT panel floor
1st floor

Figure 1 – Photograph showing the outside
view of six-story wood-frame model building

Figure 2 – Cross-sectional view of six-story
wood-frame model building

3. MEARSURMENT METHOD
3.1 Floor Impact Sound Insulation
The floor impact sound insulations were measured in conformity with requirements of JIS A 14182: 2000 (5) for the heavy-weight floor impact sound insulation and JIS A 1418-1: 2000 (6) for thelight-weight floor impact sound insulation. The impact sources for measurement of the heavy-weightfloor impact sound were a car-tire source (a bang machine) and a rubber ball source, and of the lightweight floor impact sound source was a tapping machine. The impact positions were five positions,and the sound receiving positions were five positions. The floor impact sound insulations wereevaluated with JIS A 1419-2: 2000 (7). A-weighted floor impact sound pressure levels by synthesis
were also calculated; heavy-weight floor impact sound: 31.5 to 500 Hz octave band, light-weight floor
impact sound: 125 to 2000 Hz octave band.
3.2 Airborne Sound Insulation of Separation Wall
The airborne sound insulation of separation wall was measured in conformity with requirementsof JIS A 1416: 2000 (8). The sound receiving positions were five positions in each room. The airborne
sound insulation of separation wall was evaluated with JIS A 1419-1: 2000 (9).
The measurements of airborne sound insulation of separation wall were performed on the 3rd floor
and 5th floor. The separation wall of the 3rd floor is Midply wall system which had double 12 mm thick
Oriented Strand Board and two-layer 21 mm thick fire-resistant gypsum board finish, and theseparation wall of the 5th floor is wood-frame construction and two-layer 21 mm thick fire-resistantgypsum board finish.

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3.3 Floor Vibration Performance
The floor vibration performance was measured the vibration acceleration level for the each floor.
The excitation method was dropped the rubber ball source from the height of 1 m. The vibration
measurement position was the center of the room, and a vibration level meter was used. The analysis
method was 10 ms for the time constant, and the maximum value of the vibration acceleration levelof the 1/3 octave band from 3.15 to 80 Hz band was obtained.
The results of vertical measurements were plotted in the performance evaluation curve of verticalvibration of “Guidelines for the evaluation of habitability to building vibration (10)”. V - ◯indicates the perceptual probability of ◯%. Starting from the smallest point, the line is made up of
V- 10, 30, 50, 70, 90.

4. MEARSURMENT RESOLUTS AND DISCUSSIONS

110110100

10010090909080

7060

50

21→11(CLT, Lr-num:75, 71.9dBA)
22→12(CLT, Lr-num:74, 72.4dBA)
31→21(SSP, Lr-num:71, 70.9dBA)
41→31(LVL, Lr-num:79, 74.5dBA)
42→32(LVL, Lr-num:77, 73.1dBA)
52→42(I-joist, Lr-num:78, 75.4dBA)
61→51(CT, Lr-num:80, 76.6dBA)
Lr-80
Lr-75

40

30
31.563125

250

Octave band center frequency [Hz]500

Floor impact sound pressure level [dB]110

Floor impact sound pressure level [dB]

Floor impact sound pressure level [dB]

4.1 Floor Impact Sound Insulation
Fig. 3 shows the measurement results of floor impact sound pressure level.
In the case of heavy-weight floor impact sound insulation using the car-tire source, the 3 rd floor(SSP, stress skin panel floor) yielded the highest performance, showing Lr-70 (70.9 dBA). The 4thfloor (LVL, LVL floor), the 5th floor (I-joist, I-joist floor) and the 6th floor (CT, chord truss floor)
yielded low performances, showing almost Lr-80. The 2nd floor (CLT, CLT panel floor) yielded middle
performances, showing Lr-75, and decrease in performance are seen in the 250 Hz and 500 Hz octave
bands because it is considered as resonance.
In the case of heavy-weight floor impact sound insulation using the rubber ball source, theperformance tended to be similar to that of the car-tire source. However, the 4 th floor (LVL, LVL floor)
has high performance, showing Lr-70. This is considered to be due to the non-linear response of theLVL floor to impact forces.
In the case of light-weight floor impact sound insulation using the tapping machine, the 4th floor(LVL, LVL floor) yielded the highest performance, showing Lr-75. The 2 nd floor (CLT, CLT panelfloor) yielded low performances, showing Lr-95, and decrease in performance are seen in the 250 Hz
and 500 Hz octave bands and tended to be similar to that of the heavy-weight floor impact sound.

80

7060

50

21→11(CLT, Lr-num:75, 73.6dBA)
22→12(CLT, Lr-num:76, 75.0dBA)
31→21(SSP, Lr-num:72, 72.5dBA)
41→31(LVL, Lr-num:71, 70.0dBA)
42→32(LVL, Lr-num:70, 68.7dBA)
52→42(I-joist, Lr-num:74, 74.7dBA)
61→51(CT, Lr-num:73, 72.0dBA)
Lr-75
Lr-70

40

30
31.5

63

125

250

Octave band center frequency [Hz]

500

80

70

60

50

21→11(CLT, Lr-num:93, 91.4dBA)
22→12(CLT, Lr-num:94, 92.3dBA)
31→21(SSP, Lr-num:88, 86.7dBA)
41→31(LVL, Lr-num:77, 75.2dBA)
42→32(LVL, Lr-num:73, 73.0dBA)
52→42(I-joist, Lr-num:86, 83.8dBA)
61→51(CT, Lr-num:79, 78.6dBA)
Lr-95
Lr-7540301252505001000

2000

Octave band center frequency [Hz]Figure 3 – Measurement results of floor impact sound pressure level(left: car-tire source, center: rubber ball source, right: tapping machine)

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Table 1 shows the applicable grades of the floor impact sound insulation for apartment house
specified by the Architectural Institute of Japan (11). Only the car-tire source is used to evaluate theheavy-weight floor impact sound insulation. The comparison between the results from Fig. 3 and Table
1 shows that the heavy-weight floor impact sound insulation and the light-weight floor impact soundinsulation were outside the grade range of applicable grade. The countermeasures are considerednecessary to improve the floor impact sound insulation.
Table 1 –Architectural Institute of Japan grades of the floor impact sound insulation for apartment house
Impact source
Special GradeFirst Grade
Second Grade
Third Grade
Heavy and soft source
L-45
L-50
L-55
L-60, L-65*(only Car-tire source)
Light impact source

L-40

L-45

L-55

L-60

*Apply to wooden construction, lightweight steel construction, etc.
4.2 Airborne Sound Insulation of Separation WallFig. 4 shows the measurement results of airborne sound insulation of the separation wall. The 3 rdfloor separation wall (Midply wall system) yielded level difference Dr-30, and the 5th floor separationwall (wood-frame construction) yielded level difference Dr-35.
Table 2 shows the applicable grades of the airborne sound insulation for apartment house specified
by the Architectural Institute of Japan (11). The comparison between the results from Fig. 4 and Table
2 shows that the airborne sound insulation of the separation wall was outside the grade range ofapplicable grade. The countermeasures are considered necessary to improve the airborne soundinsulation of the separation wall.
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Level difference D [dB]

5040302031→3232→3151→52

52→51

Dr-30

Dr-35

100125

250

500

1000

2000

4000

Octave band center frequency [Hz]Figure 4 – Measurement results of airborne sound insulation of separation wall, Level difference D
Table 2 –Architectural Institute of Japan grades of the airborne sound insulation for apartment house
PartSpecial GradeFirst Grade
Second Grade
Third Grade
Separation wall
D-55
D-50
D-45
D-40
Separation floor5010

Response acceleration (dB) ref.10-5 m/s24.3 Floor Vibration PerformanceFig. 5 shows the measurement results of the response acceleration level by the rubber ball source
excitation. The 6 th floor (R61, chord truss floor) has no separation wall as there is only one room.
Hence, the tendency is different from the other floors. This is due to the fundamental frequency is in
the 25 Hz 1/3 octave band. While the fundamental frequency of the other floors is in the 40 Hz bandor above as the dimensions are much larger 2.5 m × 3.6 m. The 2nd floors (R21 and R22, CLT panelfloor) have a small response acceleration, and the floor vibration performance is better than otherfloors from the viewpoint of vibratory sensation. Overall, the results on the 3 rd floor (R31, stressedskin panel floor), 4th (R41, LVL floor) and 5th floor (R51, I-joist floor) do not show much difference.
It will be necessary to conduct detailed studies including impedance characteristics.
120110
100
90

R61
V‐90
V‐70
V‐50
V‐30
V‐1080
70
60
50

R51
R41
R31
R21R224030
1101/3 octave band center frequency (Hz)100Figure 5 – Measurement results of response acceleration level by the rubber ball excitation

5. CONCLUSIONSThis paper has reported the measurement results of the floor impact sound insulation, the airborne
sound insulation of separation wall floor and the vibration performance of six-story wood-frame
model building. As the results, the following findings have been obtained.
・ It became clearer that the heavy-weight floor impact sound insulation and the light-weight floor
impact sound insulation is poor. Hence, it is necessary to conduct investigations aimed at improving
performance such as adopting a dry-type double floor structure (the floating floor) with rubber
vibration isolator which has been confirmed in previous reports.
・ The airborne sound insulation can also be considered as poor, also. We propose the methods forthe increase in airborne sound insulation; double-layer board finish, addition extra gypsum board walland insertion of the sound absorption material.
・ From the viewpoint of vibratory sensation, it is necessary to investigate the floor vibration
response by excitation and impedance characteristic of the floor.

ACKNOWLEDGEMENTS
This research was conducted as a part of the joint research of the Building Research Institute (BRI)
and the Japan 2x4 Home Builders Association. A part of this research was supported by JSPS
KAKENHI Grant Number 17K06690.

REFERENCES
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Laminated Timber Model Building for Experiment, Proc Inter-Noise 2016, Humburg, Germany, p. 37923797, 2016.

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3. Hiramitsu A, Harada K, Noji K. Effect of difference in specification on sound insulation in cross laminatedtimber separation wall, Proc ICA 2016, Buenos Aires, Argentina, 2016.
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on CLT Model Building, Proc Inter-Noise 2018, Chicago, USA, August 2018.
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Committee, 2000.
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2000.
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