Proposed Change 530

530
Last modified: 2013-10-10
Code Reference(s):
NBC10 Div.B 5.9.
Subject:
Airborne Sound Transmission
Title:
Introduce New Metric (ASTC) to Take Into Account Flanking
Description:
The proposed change introduces a new sound transmission metric in order to consider flanking sound transmission contributions in addition to the direct sound transmission currently addressed.

EXISTING PROVISION

5.9. Sound Transmission

5.9.1. Protection from Noise
5.9.1.1.Sound Transmission Class
1)Sound transmission class ratings shall be determined in accordance with ASTM E 413, "Classification for Rating Sound Insulation", using the results from measurements carried out in accordance with
a)ASTM E 90, "Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements", or
b)ASTM E 336, "Measurement of Airborne Sound Attenuation between Rooms in Buildings".
5.9.1.2.Required Protection from Noise
1)Except as provided in Sentence (2), a dwelling unit shall be separated from every other space in a building in which noise may be generated by construction providing a sound transmission class rating not less than 50, measured in accordance with the standards referenced in Sentence 5.9.1.1.(1). (See A-9.11.1.1.(1)EXISTING PROVISION A-9.11.1.1.(1) in Appendix A.)
2)Construction separating a dwelling unit from an elevator hoistway or a refuse chute shall have a sound transmission class rating not less than 55, measured in accordance with the standards referenced in Sentence 5.9.1.1.(1).
A-5.9. Required Protection from Noise.
Sentence 5.9.1.2.(1) applies to the separation of dwelling units from other dwelling units with regard to sound transmission irrespective of Clause 5.1.2.1.(1)(b), which deals with the separation of dissimilar environments. It is understood that, at any time, there is the potential for sound levels to be quite different in adjoining dwelling units.
A-5.9.1.1.(1) Sound Transmission.
The Tables in Appendix Note A-9.10.3.1.EXISTING PROVISION A-9.10.3.1. provide information on the typical sound transmission class ratings of a number of building assemblies. In the absence of test information or results for a specific assembly of materials, the values given in Tables A-9.10.3.1.A. and A-9.10.3.1.B. are considered to satisfy the intent of Sentence 5.9.1.1.(1).

PROPOSED CHANGE

[5.9.] 5.9. Sound Transmission

[5.9.1.] 5.9.1. Protection from Airborne Noise
[5.9.1.1.] 5.9.1.1.Sound Transmission ClassRequired Protection
[1] 1)Except as provided in Sentence (2), a dwelling unit shall be separated from every other space in a building in which noise may be generated by a separating assembly and adjoining construction that together provideing an apparent sound transmission class (ASTC) rating not less than 47.50, measured in accordance with the standards referenced in Sentence 5.9.1.1.(1). (See A-9.11.1.1.(1)PROPOSED CHANGE A-9.11.1.1.(1) in Appendix A.)
[2] 2)Construction separating a dwelling unit from an elevator hoistwayshaft or a refuse chute shall have a sound transmission class (STC) rating not less than 55., measured in accordance with the standards referenced in Sentence 5.9.1.1.(1).
[3] 1)Sound transmission class ratings shall be determined in accordance with ASTM E 413, "Classification for Rating Sound Insulation", using the results from measurements carried out in accordance with
[a] a)ASTM E 90, "Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements", or
[b] b)ASTM E 336, "Measurement of Airborne Sound Attenuation between Rooms in Buildings".
[5.9.1.2.] ---Determination of Sound Transmission Ratings
[1] 1)Sound transmission class (STC) ratings of separating assemblies shall be determined in accordance with ASTM E 413, "Classification for Rating Sound Insulation",using the results from measurements carried out in accordance with ASTM E 90, "Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements",.
[a] b)ASTM E 336, "Measurement of Airborne Sound Attenuation between Rooms in Buildings".
[2] --)Apparent sound transmission class (ASTC) ratings of sound transmission between adjoining spaces in a building shall be
[a] --)determined in accordance ASTM E 413, “Classification for Rating Sound Insulation,” using the results from measurements in according with ASTM E 336, “Measurement of Airborne Sound Attenuation between Rooms in Buildings,” or
[b] --)calculated according to
[i] --)the detailed method in Article 5.9.1.4., or
[ii] --)the simplified method in Article 5.9.1.5.
(See Appendix A-5.9.1.4.)
[5.9.1.3.] ---Compliance with Required Ratings
[1] --)Compliance with STC ratings shall be demonstrated by
[a] --)measurement according to Sentence 5.9.1.2.(1), or
[b] --)construction conforming to details listed in Tables B1 and B2.
[2] --)Compliance with ASTC ratings shall be demonstrated by
[a] --)measurement or calculation according to Sentence 5.9.1.2.(2), or
[b] --)construction of separating assemblies conforming to Tables B1 and B2 having an STC rating of not less than 50 in conjunction with flanking assemblies constructed according to Article 9.11.1.4.
[5.9.1.4.] ---Detailed Method for Calculating ASTC
(See Appendix A)
[1] --)The sound transmission loss measured in accordance with ASTM E90, “Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements,” shall be used in place of the sound reduction index measured in accordance with ISO 140-3, “Acoustics — Measurement of sound insulation in buildings and of building elements — Part 3: Laboratory measurements of airborne sound insulation of building elements.”
[2] --)The vibration reduction index for the junctions shall be
[a] --)determined from equations in Annex E of ISO 15712, “Building acoustics — Estimation of acoustic performance of buildings from the performance of elements,” or
[b] --)measured in accordance with Part 1 to 4 of ISO 10848, “Acoustics — Laboratory measurement of the flanking transmission of airborne and impact sound between adjoining rooms.”
[3] --)The normalized flanking level difference shall be measured in accordance with Part 1 to 4 of ISO 10848, “Acoustics — Laboratory measurement of the flanking transmission of airborne and impact sound between adjoining rooms.”
[4] --)The direct sound reduction index for the separating assembly in situ shall be determined from sound transmission loss, using Clause a) or b) depending on the type of construction:
[a] --)for a lightweight separating wall or floor assembly with wood or steel framing, as equal to the sound transmission loss, without correction,
[b] --)for a heavy separating wall or floor assembly of concrete or masonry, according to the detailed method of ISO 15712–1, “Building acoustics — Estimation of acoustic performance of buildings from the performance of elements — Part 1: Airborne sound insulation between rooms,”
[i] --)with values of sound transmission loss for the separating assembly used in place of values of sound reduction index, and
[ii] --)where lightweight linings are added to a heavy assembly of concrete or masonry, the change in sound insulation shall be determined using values of sound transmission loss in place of values of sound reduction index.
[5] --)The flanking sound reduction index for the flanking paths at each edge of the separating assembly shall be determined from values measured in laboratory tests depending on the type of constructions at each junction:
[a] --)for a lightweight separating wall or floor assembly with wood or steel framing and connected flanking assemblies with wood or steel framing, equal to the normalized flanking level difference, after-normalization consistent with ISO 15712-1, “Building acoustics — Estimation of acoustic performance of buildings from the performance of elements — Part 1: Airborne sound insulation between rooms,”
[b] --)for a heavy separating wall or floor assembly of concrete or masonry and connected flanking assemblies of concrete or masonry, using the detailed method in ISO 15712-1, “Building acoustics — Estimation of acoustic performance of buildings from the performance of elements — Part 1: Airborne sound insulation between rooms,”
[i] --)with values of sound transmission loss for each assembly used in place of values of sound reduction index, and
[ii] --)the vibration reduction index, or
[c] --)for a mixture of lightweight framed assemblies and heavy concrete or masonry assemblies, according to clause a) or b).
[6] --)The apparent sound reduction index shall be determined from the values of direct and flanking sound reduction index determined in Sentences (4) and (5), according to ISO 15712-1, ”Building acoustics —Estimation of acoustic performance of buildings from the performance of elements — Part 1: Airborne sound insulation between rooms.”
[7] --)The apparent sound transmission class (ASTC) shall be calculated according to ASTM E413, “Classification for Rating Sound Insulation,” with calculated values of apparent sound reduction index determined in Sentence (5) treated as equivalent to values of apparent sound transmission loss measured in accordance with ASTM E336, “Measurement of Airborne Sound Attenuation between Rooms in Buildings.”
[5.9.1.5.] ---Simplified Method for Calculating ASTC
(See A-5.9.1.4.)
[1] --)The sound transmission class shall be used in place of the weighted sound reduction index measured in accordance with ISO 717, “Acoustics — Rating of sound insulation in buildings and of building elements.”
[2] --)The vibration reduction index for the junctions shall be
[a] --)determined from equations in Annex E of ISO 15712, ”Building acoustics —Estimation of acoustic performance of buildings from the performance of elements ,” or
[b] --)measured in accordance with Part 1 to 4 of ISO 10848, “Acoustics — Laboratory measurement of the flanking transmission of airborne and impact sound between adjoining rooms”.
[3] --)The normalized flanking level difference shall be measured in accordance with ISO 10848,”Acoustics — Laboratory measurement of the flanking transmission of airborne and impact sound between adjoining rooms.”
[4] --)The apparent sound transmission class (ASTC) ratings of sound transmission between adjoining spaces in a building shall be determined using values for direct and flanking transmission.
[5] --)The direct sound transmission for the separating assembly shall be taken as equal to the sound transmission class (STC).
[6] --)The flanking sound transmission for the flanking paths at each edge of the separating assembly shall be determined from values determined in laboratory tests depending on the type of constructions at each junction:
[a] --)for a separating wall or floor assembly with wood or steel lightweight framing and connected flanking assemblies with wood or steel lightweight framing, using values of normalized flanking level difference re-normalized for consistency with ASTC, or
[b] --)for a heavy separating wall or floor assembly of concrete or masonry and connected flanking assemblies of concrete or masonry, using the simplified model for structure-borne transmission of ISO 15712-1, “Building acoustics — Estimation of acoustic performance of buildings from the performance of elements — Part 1: Airborne sound insulation between rooms,” with values of the vibration reduction index and STC.
[7] --)The apparent sound transmission class (ASTC) shall be calculated from the values of direct and flanking sound transmission class determined in Sentences (5) and (6), according to ISO 15712-1, “Building acoustics — Estimation of acoustic performance of buildings from the performance of elements — Part 1: Airborne sound insulation between rooms.”
[5.9.1.6.] 5.9.1.2.Required Protection from Noise
[1] 1)Except as provided in Sentence (2), a dwelling unit shall be separated from every other space in a building in which noise may be generated by construction providing a sound transmission class rating not less than 50, measured in accordance with the standards referenced in Sentence 5.9.1.1.(1). (See A-9.11.1.1.(1)PROPOSED CHANGE A-9.11.1.1.(1) in Appendix A.)
[2] 2)Construction separating a dwelling unit from an elevator hoistway or a refuse chute shall have a sound transmission class rating not less than 55, measured in accordance with the standards referenced in Sentence 5.9.1.1.(1).
A-5.9. Required Protection from Noise.
Sentence 5.9.1.2.(1) Section 5.9. applies to the separation of dwelling units from other dwelling units and spaces where noise may be generated with regard to sound transmission irrespective of Clause 5.1.2.1.(1)(b), which deals with the separation of dissimilar environments. It is understood that, at any time, there is the potential for sound levels to be quite different in adjoining dwelling units.
A-5.9.1.1.(1) Sound Transmission.
The Tables in Appendix Note A-9.10.3.1.PROPOSED CHANGE A-9.10.3.1. provide information on the typical sound transmission class ratings of a number of building assemblies. In the absence of test information or results for a specific assembly of materials, the values given in Tables A-9.10.3.1.A. and A-9.10.3.1.B. are considered to satisfy the intent of Sentence 5.9.1.1.(1).
A-5.9.1.4. Methods for Calculating ASTC.
The technical concepts, terminology, and calculation procedures of the detailed and simplified methods are discussed in detail, with numerous worked examples, in the NRC publication RR-331, “Guide to Calculating Airborne Sound Transmission in Buildings”. This Guide includes references to readily-available sources of pertinent data.
For many common constructions, calculations conforming to the requirements of Article 5.9.1.3. for the detailed calculation method can be performed using software calculation tools, such as the application SoundPATHS which is available on the website of the National Research Council of Canada.
The simplified calculation method tends to result in lower values for the ASTC than the detailed method and may not always identify the prominent flanking paths. The simplified method agrees with the detailed method more closely where the separating assembly and the flanking constructions are both of the same construction method, either both are light framed construction (steel or wood), or both are masonry or concrete construction.

RATIONALE

General information

Problem

The requirements in the National Building Code (NBC) with regard to sound transmission are based on the best available information at the time they were introduced. The requirements focus on the laboratory rating of the separating assembly, rather than performance of the system.

Advances in the field of acoustical research now make it clear that this falls well short of achieving a level of performance consistent with the objectives of the Code. The current provisions encourage an over-simplified design approach that results in frequent investment in the wrong elements and most importantly fail to provide a functional requirement that establishes a minimum acceptable performance necessary to satisfy the Objective OH3 Noise Protection.

Justification - Explanation

Switching from the current STC rating to the Apparent Sound Transmission Class (ASTC) rating would address the minimum performance of the complete system without over-design and with minimal implication to the scope of the NBC and enforcement.

There are currently no metrics that address noise generated by elevators. Therefore by simply increasing the criteria for a required (airborne) STC rating – as is currently done in the NBC – was considered better than no requirement at all.

Cost implications

For building designs where flanking is not currently addressed, there might be a cost for re-design to limit flanking. In many instances, this cost would be offset by savings in material and labour because the proposed change would eliminate the current approach of over-design of the separating element promoted in the appendix note.

Inadequate protection from noise can have serious health implications. A World Health Organization report demonstrates the relationship between noise intrusion, annoyance, and adverse health effects such as increased stress, compromised immune systems, and depression. A British study estimates “there are between one and ten deaths per year in the U.K. (these being suicides or as a result of assaults) attributed to noise from neighbours.”

There are cost savings from failures in the field where the in-situ performance of assemblies is significantly reduced by flanking sound transmission that was not considered during the design.

Enforcement implications

 None – The way the current requirements for airborne sound transmission are enforced is by verifying the construction of assemblies according to Table A-9.10.3.1. or by acknowledging lab or field test results. In addition to these procedures a similar process would apply to select appropriate flanking constructions for adjoining walls and floors.

A new design/calculation procedure is being proposed for Part 5, which would be enforced similar to calculation results for structural design, fire resistance or energy efficiency.

Who is affected

 Builders, building officials, designers, manufacturers.

OBJECTIVE-BASED ANALYSIS OF NEW OR CHANGED PROVISIONS

[5.9.1.1. 5.9.1.6.] 5.9.1.2. ([1 1] 1) [F56-OH3.1]
[5.9.1.1. 5.9.1.6.] 5.9.1.2. ([2 2] 2) [F56-OH3.1]
[5.9.1.1. 5.9.1.2.] 5.9.1.1. ([3 1] 1) [F56-OH3.1]
[5.9.1.1. 5.9.1.2.] 5.9.1.1. ([3 1] 1) [F56-OH3.1]
[5.9.1.2.] -- ([2] --) [F56-OH3.1]
[5.9.1.3.] -- ([1] --) no attributions
[5.9.1.3.] -- ([2] --) no attributions
[5.9.1.4.] -- ([1] --) [F56-OH3.1]
[5.9.1.4.] -- ([2] --) [F56-OH3.1]
[5.9.1.4.] -- ([3] --) [F56-OH3.1]
[5.9.1.4.] -- ([4] --) [F56-OH3.1]
[5.9.1.4.] -- ([5] --) [F56-OH3.1]
[5.9.1.4.] -- ([6] --) [F56-OH3.1]
[5.9.1.4.] -- ([7] --) [F56-OH3.1]
[5.9.1.5.] -- ([1] --) [F56-OH3.1]
[5.9.1.5.] -- ([2] --) [F56-OH3.1]
[5.9.1.5.] -- ([3] --) [F56-OH3.1]
[5.9.1.5.] -- ([4] --) [F56-OH3.1]
[5.9.1.5.] -- ([5] --) [F56-OH3.1]
[5.9.1.5.] -- ([6] --) [F56-OH3.1]
[5.9.1.5.] -- ([7] --) [F56-OH3.1]
[5.9.1.1. 5.9.1.6.] 5.9.1.2. ([1 1] 1) [F56-OH3.1]
[5.9.1.1. 5.9.1.6.] 5.9.1.2. ([2 2] 2) [F56-OH3.1]