Download CJ Buma - Steelform Building Products Inc.

aci Acoustical Consultants Inc.
Suite 107, 9920-63Ave
Edmonton, Alberta, Canada T6E 0G9
Phone: (780) 414-6373, Fax: (780) 414-6376
www.aciacoustical.com
To:
Steelform Building Products Inc.
4104 – 69 Avenue
Edmonton, AB, T6B 2V2
Wednesday, 2007 May 7
Attn: Mr. Marty MacDonald
re:
Acoustical Testing Results of Steelform Products
Dear Marty,
Thank you for retaining aci to conduct STC field testing at the Park One Condominium
Building. The results and discussion of the testing are attached. We trust the information
provided is sufficient. Please contact us if you have any questions.
Yours very truly,
aci Acoustical Consultants Inc.,
CJ Buma
Corjan Buma, M.Sc., P.Eng.
Associate Consultant
APEGGA Permit to Practice # P7735
Project #06-044
Field STC Study Using Steelform Products
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2007 May 7
INTRODUCTION
aci Acoustical Consultants Inc. of Edmonton was retained by Steelform Building Products Inc.
to conduct standarized acoustical measurements of some of its stud and joist products as installed
at the Park One condominium located at 111 Street and 68 Avenue in Edmonton, AB. The
purpose of this study was to determine the STC (sound transmission class) performance across a
party wall and one floor/ceiling assembly within the building. Site work was conducted for aci
by Corjan Buma, M.Sc., P.Eng., on Friday, 2007 Febr. 2.
MEASUREMENT METHODS
STC TEST
The STC testing was done using the ASTM E336 standard “Standard test method for
measurement of airborne sound insulation in buildings” as a guideline. The general procedure
involves producing a loud source of sound on one side of the measured partition with a
loudspeaker, as shown in Figure 1, producing “pink noise”. Sound level measurements are
conducted on the source side at several locations (to be averaged in post-processing) and on the
receiver side at several locations. The difference in sound levels between the two locations is
known as the Transmission Loss (TL). Finally, a measurement of the reverberation time within
the receiver space is conducted to allow for adjustment of the receiver sound pressure levels in
accordance with the ASTM standard.
The results are used, along with the area of the tested partition and the volume of the receiver
room to calculate the adjusted TL values in each of the measured 1/3 octave band frequencies.
Finally, a standardized STC curve is fitted to the adjusted TL curve according to the fitting
criteria outlined in the ASTM standard. The resultant value of the standard curve at 500 Hz is
known as the STC value. This value, being measured in a constructed building, is known as the
Apparent STC (ASTC). The ASTC value is generally lower than the laboratory achievable STC
value (known as the “rated STC”) because there are typically (1) additional noise flanking paths
around the partition and (2) mechanical and/or electrical components that allow noise transfer
through the partition; both of these are intentionally minimized or prevented in laboratory
testing. As such, the reported ASTC value is a measure of the overall construction performance.
Table 1 shows a range of STC and ASTC values and typical subjective response.
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Table 1. Subjective Performance of Various STC Values
STC Lab
26-30
Apparent STC
22-26
30-35
26-31
35-40
31-36
Subjective description of effectiveness
Most sentences clearly understood
Many phrases and some sentences understood without
straining to hear
Individual words and occasional phrases clearly heard and
understood
42-45
38-41
Medium loud speech clearly audible, occasional words
understood
47-50
43-46
52-55
48-51
Normal speech audible by straining to hear. Loud speech
audible, music easily heard
Normal speech unintelligible, Loud speech audible by
straining to hear; music normally can be heard and may be
disturbing
57-60
53-56
Loud speech essentially inaudible; music can be heard
faintly but bass notes disturbing
62-65
57-61
Music heard faintly, bass notes "thump"; power
woodworking equipment clearly audible
70
75+
65
65+
Music still heard very faintly if played loud.
Effectively blocks most air-borne noise sources
The measurement equipment for the STC testing consisted of a Brüel and Kjær Type 2250
Precision Integrating Sound Level Meter, collecting data in 15-second Leq samples measuring the
broadband A-weighted and 1/3 octave band frequency sound levels. The sound level meter was
calibrated at the start of the measurements to ensure accurate results.
The sound source
consisted of a NTI Minirator MR1 generating pink noise and a JBL EON-G15 loudspeaker.
Reverberation time measurements were conducted with the loudspeaker (used for room
excitation) and the Sound Level Meter as both the source and measurement system. Refer to the
Appendix for calibration certificates for the Sound Level Meter.
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BACKGROUND SOUND LEVEL CONSIDERATIONS
Note that during all tests the sound level in each of the pertinent 1/3 octave bands is required to
be at least 10 dB above the ambient sound level (with the source signal turned off). This ensures
that the measured sound is loud enough to not have interference from the other constant sources
such as ventilation and other equipment. As such, measurements in the receiver room are
conducted with the source sound both on and off and then compared after the test. Some of the
STC tests occurred with receiver room levels less than 10 dB above ambient in several of the 1/3
octave bands; this was due to either low-level sound due to Contractors still at work in the
building or the in-suite air-handling equipment being “on”.
In general, the deficient 1/3 octave values were not responsible for determining the resultant
ASTC value. However, where the ASTC value did appear to be affected by higher-thandesirable background sound level, the results are reported with the ASTC value followed by a
“+” sign, indicating that the actual ASTC would have been slightly higher had background noise
not interfered with the result.
TEST LOCATIONS
An “up-down” assessment of a floor/ceiling assembly was conducted from Unit 203 to Unit 103
and a side-to-side assessment of a party wall was conducted from Unit 405 to Unit 404. The
suites tested were all unoccupied, having been finished to the degree of painting, baseboards,
millwork and most doors in place. Some of the bedrooms had been equipped with finish flooring
(in the form of carpet or lino or laminate). There were no obvious holes/leaks between any of
the units though typically party-walls did have an electrical box into the room on either side.
Some doors had not yet been equipped with handles (resulting in a 50-mm open hole) and none
were equipped with perimeter seals. Subjective listening/assessment during side-to-side STC
testing (Unit 405 to Unit 404) verified that the lack of perimeter seals and lack of some doorhandles was not the determining factor in STC results.
Unit 203 to Unit 103
The STC assessment from Unit 203 to Unit 103 was done in the living room area and assessed
the performance of Steelform joists in a floor/ceiling construction.
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The floor/ceiling assembly consisted of 22-gauge metal deck, filled with concrete topping
(minimum thickness 38 mm), on 150-mm Delta joist, 50-mm Spider insulation applied to
underside of deck, furring bar (“hat channel”) below Delta joist and one layer 16-mm Type X
drywall attached below furring bar.
Unit 405 to Unit 404
The side-to-side STC test was done from Unit 405 Bedroom and Unit 404 Bedroom. The
composition of this party wall was Delta stud on both sides of 25-mm gap (no board material
within 25-mm gap), common batt insulation in stud-cavities on both sides of gap and one layer
of 16-mm Type X drywall on one side and two layers of 16-mm Type X drywall on the other.
(Note that there is acoustically no difference whether the sound source is on the 2-layer or the 1layer side of the party wall.)
RESULTS OF STC TESTS
The results of the STC tests are shown in Table 2 and Figures 2 & 3. The value of ASTC 58 is
considered “very good” (an ASTC value of 55 or more would qualify as “superior sound
isolation”). The value of ASTC 53 is considered “good”.
Table 2. Derived ASTC Values
Source
Receiver
ASTC
Unit 203
Unit 103
58
Unit 405
Unit 404
53
For reference, the Alberta Building Code states (in Section 9.11):
“… every dwelling unit shall be separated from every other space in a building
in which noise may be generated by a construction providing a sound
transmission class rating of at least 50, measured in accordance with
Subsection 9.11.1 or as listed in A-9.10.3.1. in Appendix A”
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The test method discussed in Subsection 9.11.1 refers directly to ASTM E 336 (which was
followed as part of this test). Thus, the tested value of ASTC 58 appreciably exceeds the
requirement of the Alberta Building Code.
For the fourth floor result, had Spider insulation been used on fourth floor, the ASTC may well
have gone above 53 (assumes Spider insulation is more dense than common batt insulation).
CONCLUSION
The results of the ASTC in-situ testing of the Steelform products indicate that building code
requirements can be met, and even exceeded, with the use of the Steelform products.
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Figure 1. Sound Source Used for STC Testing (Unit 203)
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100
90
Sound Transmission Loss (dB)
80
70
60
STC 58
50
40
30
20
10
0
125
250
500
1000
Frequency (Hz)
2000
4000
Figure 2 – ASTC Result For Floor/Ceiling Between Living Rooms of Units 203 & 103
100
90
Sound Transmission Loss (dB)
80
70
60
STC 53
50
40
30
20
10
0
125
250
500
1000
Frequency (Hz)
2000
4000
Figure 3 – ASTC Result For Party-Wall Between Bedrooms of Units 405 & 404
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APPENDIX
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B&K 2250 Calibration Certificate(s)
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B&K 4231 Calibrator Calibration Certificate
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