5.8.1.5.Simplified Method for Calculating ASTC (See Note A-5.8.1.4.)

(0.1) This Article sets out the simplified method for calculating ASTC ratings of separating assemblies and adjoining construction referred to in Subclause 5.8.1.2(2)(b)(ii). (1) The STC rating shall be used in lieu of the weighted sound reduction index required in ISO 15712-1, “Building Acoustics - Estimation of Acoustic Performance of Buildings From the Performance of Elements - Part 1: Airborne Sound Insulation Between Rooms.” (2) The vibration reduction index for the junctions between separating assemblies shall be, (a) determined using the equations presented in Annex E of ISO 15712-1, “Building Acoustics - Estimation of Acoustic Performance of Buildings From the Performance of Elements - Part 1: Airborne Sound Insulation Between Rooms,” or (b) measured in accordance with Parts 1 to 4 of ISO 10848, “Acoustics – Laboratory Measurement of the Flanking Transmission of Airborne and Impact Sound Between Adjoining Rooms – Part 1: Frame document.” (3) The weighted normalized flanking level difference shall be determined in accordance with ASTM E413, “Classification for Rating Sound Insulation,” using the results from measurements carried out in accordance with Parts 1 to 4 of ISO 10848, “Acoustics – Laboratory Measurement of the Flanking Transmission of Airborne and Impact Sound Between Adjoining Rooms – Part 1: Frame document.” (4) The direct weighted sound reduction index for the separating assembly shall be taken as equal to the STC, without correction. (5) The weighted flanking sound reduction index for each flanking path at each edge of the separating assembly shall be determined in accordance with Clause (a) or (b), depending on the type of construction: (a) for a lightweight separating wall or floor assembly with wood or steel framing and connected lightweight flanking assemblies with wood or steel framing, the index shall be taken as equal to the weighted normalized flanking level difference re-normalized for the ASTC field situation in accordance with Annex F of 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 heavyweight separating wall or floor assembly of concrete or masonry and connected flanking assemblies of concrete or masonry , the index shall be determined in accordance with the simplified method for structure-borne transmission presented in ISO 15712-1, “Building Acoustics - Estimation of Acoustic Performance of Buildings From the Performance of Elements - Part 1: Airborne Sound Insulation Between Rooms”. (See Note A- 5.8.1.4.(4)(b)) (6) Once the pertinent indices and measurements referred to in Sentences (1) to (5) have been determined based on the type of construction, the ASTC shall then be calculated in accordance with ISO 15712-1, “Building Acoustics - Estimation of Acoustic Performance of Buildings From the Performance of Elements - Part 1: Airborne Sound Insulation Between Rooms.”