PROCEEDINGS of the
23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

The increment in cost and other parameters to upgrade quality
classes in sound insulation
Bilge SAN OZBILEN1; Nurgun BAYAZIT2
1,2

Istanbul Technical University, Turkey

ABSTRACT
Providing comfortable environments for users is the main objective for architects at the design process today.
Physical performance parameters of building elements such as sound insulation, thermal insulation,
resistance to fire and moisture are evaluated primarily for user comfort. However, in design phase, elements’costs, thicknesses and weights are considered as well. To ensure sound insulation, according to Acoustic
Regulation of Turkey, minimum quality class of C should be provided. Practices like adding layer orincreasing weight to upgrade quality class from C to A or B, generally are in conflict with the cost criterion.
In this study, 509 number of internal masonry wall alternatives made of brick and autoclaved aerated concrete
blocks are evaluated. This paper presents results of the calculation of required increments as percentages incost, thickness and weight to upgrade quality classes.
Keywords: Quality Class, Sound Insulation, Cost

1. INTRODUCTION
The construction sector in the world is growing every year. By the year 2025, it is estimated that theratio of the construction sector in the total economy will reach 10% in developed countries and 17% indeveloping countries (1). So far, the growth in constructions has led to many environmental problems
and has increased the need for sustainable building design.
Sustainable buildings focus mainly on energy conservation and improvement of the quality ofbuildings for occupants. User comfort, which can be defined as the state of wellbeing amongst
building users, is achieved by controlling factors such as heat, light, sound, water and fire. Selection
and use of proper building materials is very important in providing these parameters (2).
To ensure sound insulation in Turkey, “Regulation on Protection of Buildings Against Noise” waspublished on 31 May 2017 by Turkish Ministry of Environment and Urbanization. The regulation
categorizes acoustical performance of buildings and specifies the limit values in terms of 6 parameters:
airborne sound insulation, impact sound insulation, façade sound insulation, indoor background noise,mechanical noise and reverberation time. For each parameter, the limit values are defined, according
to acoustical performance class ranging from A to F. Every building should comply with minimu mrequirements. For new buildings, at least C acoustic performance class should be provided. For
buildings aiming A or B acoustic performance class, “Acoustic Performance Certificate” is acompulsory document that is used to evaluate and certify acoustic conditions of the building (3).
To upgrade from C to B or A classes and to obtain this certificate, making improvement is necessary
primarily at the airborne sound insulation performance of the building elements. For improving soundinsulation, general principles can be summarized as 1- increasing mass&density by means of increasein thickness 2- designing double wall 3-providing flexible connections 4- introducing an air gap
between layers 5- increasing the air gap thicknesses 6- using porous elements in the cavity 7- avoiding
factors that will form a sound bridge between walls, such as insulating the connection points of theelements like service pipes, ducts passing through the walls etc. (4).
12sanbi@itu.edu.tr
nurgun@itu.edu.tr

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However, in decision phase, effect of these applications on other design parameters should also betaken into consideration. Firstly, these practices affect “cost” which is another important criterion in
evaluating the function of a building. Considering that resources are limited, minimizing cost should
always be the main objective for projects. Secondly, additional layers added to building elements
increase weight. But, designing lightweight buildings is important in Turkey since 92% of the country
is in earthquake zones (5). Lightweight wall materials decrease pressure on load-bearing system andincrease resistance to earthquake. Thirdly, designing thicker walls to increase sound insulation
performance both increase unit cost and the weights. It changes heat gains and losses in buildings andaffects their energy consumption as well. For this reason, determination of the optimum thickness isimportant in design.
This paper examines the effect of improvement in sound insulation performance of walls on cost,weight and thickness criteria by generating basic wall alternatives between two rooms (source andreceiver rooms) and calculating values of all criteria. Finally, increment in cost, weight and thickness
parameters depending on the change in the sound insulation performance corresponding to acoustical
performance classes were evaluated statistically.

2. METHODOLOGY
2.1 Criteria, Objectives and Limit Values
According to Building Census by Turkish Statistical Institute, 75% of total buildings are used as
housing. In addition, 51% of total buildings are built in masonry, 48.4%, frame system, and 0,6% otherconstruction systems (6). So, in this study residential buildings with masonry walls are studied.
Airborne sound insulation performance was calculated at the partition wall between bedroom of asimple residential building (receiver room) and an adjacent room (source room). Volume of thereceiver room is considered as 50 m 3 as specified in the ISO 10140-5 standard. According to thisstandard, wall dimensions should be approximately 10 m 2 (7). Therefore, wall dimensions were taken
as length (l): 4 m, height (h) 2,7 m, and area (a) 10,8 m2 .
Sound and receiver rooms have been considered to have equal internal temperatures. So, thermal
insulation and condensation parameters have not been analyzed. For protection against fire, in order tobe in compliance with “Regulation on Fire Protection in Buildings” all construction elements wereselected as Class A1 non-combustible material (8).
Wall types and building materials were selected so as to be the most widely used types andmaterials in Turkey. Sound insulation performance (DnT,A, dB), cost (Euro/m 2 ), weight (kN/m 2 ), andthickness (cm) criteria of the walls were calculated and discussed.
2.1.1 Airborne Sound Insulation
Minimum airborne sound insulation values to be provided according to source and receiver room
specifications (D nT,A, dB) are determined in “Regulation on Protection of Buildings against Noise”
given at Table 1 (4). According to Table 1, first, buildings are categorized according to their noise
sensitivity and noisiness. Then, sound insulation values are defined according to the combinations ofdifferent levels of noisiness and sensitivity. In this study, receiver room properties were selected as aresidential bedroom that is highly sensitive to noise (Degree I) and adjacent source room is regarded asmoderate noisy (MN). In this combination, the limit values are 52 dB for C-Class, 58 dB for B-Classand 62 dB for A-Class.
D nT,A value was obtained from the following formula (9)DnT,A = DnT,w +C dB(1)and଴Ǥଵ଺௏
଴Ǥଷଶ௏ᇱᇱ
(2)‫ܦ‬௡்ǡ௪ ൌ ܴ௪൅ ͳͲ  ቀ ் ቁ ൌ ܴ௪൅ ͳͲ  ቀ ௌ ቁ dB
బ ௌೞ

ೞ

where
Ss : Area of part t on wall, m2
T 0 : Reference reverberat on t me (0.5s for houses)
V: Volume of rece ver room, m3
and
R'w = Rw - CF
(3)
C F: Correction value is calculated by the ratio of the unit weight of partition element (X) to average
unit weight of all elements causing flanking transmissions (Y). For x=X /Y then CF value is obtained
according to Table 2.

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Table 1 –Minimum airborne sound insulation values to be provided according to source and receiver room
specifications (DnT,A, dB) (4). L m ts for MN-I
Acoustical Performance Class

Source Room

Receiver Room

No s ness Level

Sensitivity Level

A

B

C

D

E

F

High Level ofI - h gh

68

64

58

54

50

46

Noisiness (HN)II – moderate

65

61

55

51

47

43

LAF,max > 75 dB

III - low

62

58

52

48

44

40

Moderate

I - h gh

62

58

52

48

44

40

Noisiness (MN)

II – moderate

59

55

49

45

41

37

75 ≥ LAF,max > 55 dB

III - low

56

52

46

42

38

34

Low Level ofI - h gh

56

52

46

42

38

34

Noisiness (LN)

II – moderate

53

49

43

39

35

31

LAF,max ≤ 55 dB

III - low

50

46

40

36

32

28

Table 2 – CF : correct on value (9)
x

x≤1

1<x≤2

2<x≤3

3<x

CF

0

2

4

6

In order to determine Rw (C; C tr) values, INSUL sound insulation prediction software has been used.
INSUL is based on models created by applying mass law theory that takes into account the criticalfrequency and approaches developed by B.H. Sharp, Cremer, Fahy, Ljunggren, R ndel and others. It
has been noted that the program reliably predicts sound insulation values with a 3-5 dB approximation(10).
In the calculation of C F values, it was accepted that unit weights of the walls are equal. The lower
and upper floors were considered as 15 cm reinforced concrete.
2.1.2 Cost
In Turkey, for construction cost estimation, “Construction Unit Price Methodology” by The
Ministry of Environment and Urbanism is widely used. Within the scope of construction unit pricemethod; inputs of unit price are labor, machinery-equipment and material. A short description of thework for each of the inputs (laborer, mason etc.), machinery-equipment (excavator, bulldozer etc.) andmaterial (brick, sand, cement etc.) are listed, unit and unit price of the work has been determined witha code number given in the Construction and Installation Unit Prices Book (11). An example of a unit
price cost estimation is given at Table 3. Values were calculated in Turkish Lira (TRY) at first and thenconverted into Euro (EUR) (12).
2.1.3 Weight
Loads than can act upon a structure are generally classified as permanent (dead) loads, imposed(live) loads, horizontal loads and other loads such as load caused by temperature difference. Deadloads refer to the structure's self-weight and generally remain constant during the structure's life. Liveloads, such as traffic loads may vary. Earthquake load and wind load are example to horizontal loads.
In this study, only permanent-self loads of the non-load bearing walls were calculated. Total load of thewall is calculated as the sum of all elements’ weight constituting the wall such as block, mortar, plaster,
steel studs, rockwool, gypsum board etc.
2.2 Creating Non-Load Bearing Masonry Internal Wall Alternatives
Generating wall types were started with the design of a single wall. Afterwards, alternatives were
multiplied considering the general principles for improving sound insulation such as increasing
mass&density by means of increase in thickness, adding layer, designing double wall, introducing an
air gap between layers, increasing the air gap thicknesses and using porous elements in the cavity.

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Table 3 – Example of unit cost calculation (11)Item No

Analysis Name

Unit

15.220.1003

Building walls using 200-mm horizontally perforated bricks

m2

Item No

Unit of

Definition

MeasureQuantity

Unit

Amount

Price

(TRY)

Material:
10.130.2010

250 x 250 x200-mm horizontally perforated
bricks (Including losses)

19.100.2416 Preparing lime mortar (with slaked lime bags)
10.130.9991 Water

Qty

15,00

1,06

15,90

m3

0,018

141,40

2,55

3

m

0,01

6,84

0,07

h

0,68

15,70

10,68

h

1,36

11,50

15,64

Labor:
10.100.1013

Master bricklayer

10.100.1062 Unskilled worker (Construction worker)(Including loading, horizontal and verticalhandling unloading at the construction site)
Material + Labor Cost:

44,84

25% contractor's profit and overheads

11,21

2

Price per m(1) 53,29 TRY=7,89 Euro (21 May- CBRT Exchange Rates)(12)56,05 (1)

Alternatives are presented in the Table 4 below. Paint application on wall is not included in the study
because it depends on the subjective preferences in projects.
2.3 Building Materials
In Turkey, according to Building Census, most commonly used infilling wall material is specified
as brick for masonry buildings (6). In addition, Turkey is one of the biggest global AAC producers in
Europe (13). Therefore, brick and AAC blocks were preferred as wall materials for the study. Bricks
used in this study are categorized in EN 771-1 as clay masonry units with LD (low gross dry density)
and Category I (Level of confidence). Type of bricks are vertically perforated (VP), horizontally
perforated (HP) Class-AB, horizontally perforated (HP) Class-W (14). AAC blocks were selected as
non-reinforced blocks in EN 771-4 (15).
In determination of the thicknesses and densities, Unit Price Book of the Ministry of Environment
and Urbanization has been taken into consideration which gives information about the most produced
materials (11). Since the target is to provide minimum wall thickness, blocks larger than 15 cm were
not calculated for double walls. Densities and thicknesses for the bricks and AAC blocks are given in
Table 6. Other properties were considered as following: Elasticity Modules (E, GPa): 2,5 for HP, 3 for
VP-650kg/m3, 4 for 750kg/m 3 ,1,75 for AAC 400 kg/m 3 , 2,25 for AAC 500 kg/m 3 and 2,75 for AAC
600kg/m3 . Loss factors are 0,01 for both bricks and AAC blocks. Poisson’s Ratio’s (σ) are 0,25 forboth bricks and AAC blocks. Properties of the other materials are: Gypsum board: 1,25 cm - 640 kg/m3 ,Rockwool: 5 cm 50kg/m 3 , Cement Plaster: 2 cm 2000 kg/m3 , Brick Mortar: Lime Cement Mortar-1800
kg/m3 . For AAC Block instead of mortar, special adhesive is used.
2.4 Calculation of Number of Alternatives
Regarding the multiplication of the number of density and number of thickness, it is calculated that
number of alternatives are 60 for Type 1, 19 for Type 2a, 19 for Type 2b, 19 for Type 2c, 240 for Type3, 152 for Type 4. Therefore, total amount of calculated walls is 509.

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Table 4 – Internal wall alternatives
Alternatives
Type 1 (1)Type 2(1)Single Wall

Double Walla) 2 cm airgapb) 5 cm airgap

Type 3 (2) (3)Type 4 (2) (3)Single Wall+ Wall Lining

Double Wall+ Wall Liningc) 5 cm Rockwool

5-G

7,5-G

a-5-G

a-7,5-Gb-5-G

b-7,5-G5-2G

7,5-2G

a-5-2G

a-7,5-2G

b-5-2Gb-7,5-2G(1) Cement plaster on two side(2) Cement plaster on one side(3) 5 - G: 5 cm rockwool

n 5 cm a rgap + s ngle layer gypsum board
7,5 - G: 5 cm rockwool n 7.5 cm a rgap + s ngle layer gypsum board
5 - 2G: 5 cm rockwool n 5 cm a rgap + double layer gypsum board
7,5 - 2G: 5 cm rockwool n 7.5 cm a rgap + double layer gypsum board
w th DU50 or 75 and DC50 or 75 metal cladd ng prof lesTable 5 –Properties of the materials
Material

Code
HP

Brick
AAC

VP

(kg/m3)
600

W
AB

AAC

Thickness (cm)Dry Density

650 - 750
400 - 500 -600

(Not calculated for double walls)
10 - 12 - 13,5

19 - 20 - 24 – 25

11,5 - 14,5

17,5 - 19 - 24 - 25 - 30-

19 - 24 - 29

10 - 12,5 - 13,5 - 15

17,5 - 19 - 20 - 22,5 - 25 - 30 - 35

3. RESULTS OF THE STUDY
According to the sound insulation calculations, 54 wall types were found to be < 52 dB – the limit
for C-Class and excluded from the analysis. Thus, number of 455 walls were analyzed. Of the 455
walls, it was calculated that, 84 number of walls were in Class C, 136 number of walls were in Class B
and 235 number of walls were in Class A.
Statistical analysis of the data has been performed by using IBM SPSS 25 (Statistical Package forSocial Sciences) (16). Evaluations were made for determining relationships between criteria of thestudy using Spearman's correlation. Table 6 points out Spearman's correlations for all variables. All
the correlations have 455 sample size (N) and they all have 2 -tailed 0.01 level significance.
Considering the correlation coefficient is weak for 0.1-0.29 moderate for 0.3-0.49 and strong for
0.5-1,0 values; looking at the Table 6, it can be confirmed that, between all variables there appears to6993

be a strong positive correlation except the correlation between sound insulation and weight which ismoderate.
Table 6 –Spearman 's correlations for data
Var able 1

Var able 2

Correlat on Coeff c ent (1)Sound Insulation (DnTA – dB)

Cost (Euro/m2)

0,695Sound Insulation (DnTA – dB)

Th ckness (cm)0,688Sound Insulation (DnTA – dB)

We ght (kN)0,395

Cost (Euro/m )Th ckness (cm)0,832

Cost (Euro/m2)

We ght (kN)

0,538

2

Th ckness (cm)We ght (kN)
All the correlat ons are s gn f cant at the 0.01 level (2-ta led).

0,785

(1)

Besides, variation of cost (Euro/m 2) weight (kN/m 2 ) and wall thickness (cm) related to airborne
sound insulation values of acoustical performance classes (D nTA - dB) for MN-I combination has been
examined. Minimum, maximum, range, mean, median, std. deviation values were calculated for eachclass for all criteria. Results of the calculations are given in Table 7 and graphs of the analysis arepresented at Figure 1-3. Figures illustrate min, max and median values depending on the parametercorresponding each of the sound insulation performance value.
When Table 7 is evaluated, mean (average) and median values are found to be close to each other.
Analyzing the median values, it can be specified that, in order to upgrade classes, the required
increment is, for cost criterion, from C-Class to B-Class 3,1%, from B to A 23,2 and from C to A 27%;
for weight criterion, from C-Class to B-Class -6,4 % from B to A 24,3 % and from C to A 16,3% ; forthickness criterion, from C-Class to B-Class 4,4% and from B to A 29,7 %, from C to A 35,4%.
These results demonstrate that for MN-I combinations, with the wall alternatives taken in this study,
upgrading from C to B Class requires less than 5% increment. But transition to A Class from C or B
requires increment more than approximately 20% for cost, %15 for weight and %30 for thickness.

Figure 1 – Variation of cost (Euro/m2) related to airborne sound insulation values of acoustical performanceclasses (DnTA - dB) (for MN-I combination)

4. CONCLUSIONSTo provide sound insulation in buildings, sound insulation performances of building elements
should ensure the limit values of the Acoustic Regulation of Turkey. Limit values are classified

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Figure 2 – Variation of weight (kN/m2) related to airborne sound insulation values of acoustical performanceclasses (DnTA - dB) (for MN-I combination)

Figure 3 – Variation of wall thickness (cm) related to airborne sound insulation values of acoustical
performance classes (DnTA - dB) (for MN-I combination)according to acoustical performances classes, between A to F. For new buildings minimum C Class isrequired. Acoustic Performance Certificate will be prepared for buildings performing A or B Classes.
Modifications in building elements to provide or enhance sound insulation affect other importantparameters such as cost, weight and thickness.
In this study, 509 non-load bearing brick and AAC block wall alternatives were created between
source and receiver rooms. Insulation limits for walls were specified considering source room is highsensitive to noise (degree I) and receiver room is moderate noisy (MN). Wall alternatives were formed
as single wall, double wall and walls with cladding. After all parameters were calculated, 54 of thewalls were eliminated for having lower values than the C-Class limits. As a result, 455 of the walls
were evaluated statistically. Between parameters, high correlation has been observed with theSpearman’s correlations. In addition, required increments as percentages in cost, thickness and weight
to upgrade quality classes has been calculated and analyzed. Results indicate that, for limits of MN-I
combination, to upgrade from C-Class to B-Class average of approximately 5% increment is necessary
for all parameters. However, upgrading to A Class from C or B requires average of approximately morethan 20% for cost, %15 for weight and %30 for thickness. Further studies are required to evaluate thechange of parameters for other combinations of noisiness and sensitivity.

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Table 7 – Statistical analysis of each class
Cr ter aClass

Minimum

Maximum

Range

Mean

MedianStd. Dev.

Sound

C

52

57

5

55,61

56,00

1,389

Insulation

B

58

61

3

59,68

60

1,039

(DnTA - dB)

A

62

75

13

67,49

67

4,047

C

13,0

22,1

9,1

16,3

15,9

1,9

B

13,9

23,6

9,7

16,9

16,4

2,0

A

15,1

24,8

9,7

20,2

20,2

2,4

C

1,07

3,35

2,28

1,95

1,96

0,54

B

1,15

3,14

1,99

1,89

1,84

0,47

A

1,62

3,15

1,53

2,31

2,28

0,34

C

18,00

43,00

25,00

28,18

28,25

5,77

B

20,00

46,00

26,00

29,62

29,50

5,95

A

25,50

47,00

22,00

38,08

38,25

4,84

Cost
(Euro/m2)
Weight(kN/m2)Thickness(cm)

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