The 2015 edition of the National Building Code of Canada (NBCC) includes significant changes to the acoustic requirements for residential constructions. The 2015 edition defines the acoustic requirements in terms of the Apparent Sound Transmission Class (ASTC) rating which includes contributions from flanking transmission and therefore is a better descriptor of how well the sound insulation of a building will actually protect the inhabitants of the building from unwanted noise than the STC rating which was used in earlier editions of the NBCC. The 2015 NBCC requires an ASTC rating = 47 for constructions between dwelling units.
The ASTC rating that a construction will achieve depends on the design of the building elements including the gypsum board, the framing and the thermal insulation as well as the design of the junctions between the building elements. Changes to the building elements or the junctions will change the ASTC rating.
Fifty five examples of the calculation of the ASTC rating for typical mid-rise wood constructions (single and triple staggered wood stud walls and floors constructed of I-joists) with 15.9 mm (5/8”) SilentFX® QuickCut gypsum board, 15.9 mm CertainTeed Type X gypsum board and CertainTeed Sustainable fiberglass insulation are presented. All of the constructions shown in the examples have an ASTC rating which is greater than 47.
In addition to the examples for mid-rise wood framing, an example using 15.9 mm SilentFX® QuickCut gypsum board as a lining on a cross laminated timber (CLT) construction is also presented.
Project contact is Sylvain Ménard at Université Laval
Summary
In order to ensure the acoustic performance of timber constructions, the research group of the Sustainable Building Institute at Napier University has established a series of proven solutions. These, called rugged construction details, are based on a series of designs that are most likely and proven for the performance they will bring into the building. The advantage of this approach is to provide designers with solutions that have been the subject of technical validations, thus allowing them to free themselves from the burden of offering the builder an acoustic solution. The tools to develop this concept will involve an understanding of the propagation of impact and airborne noise in the main building design typologies in CLT, to validate the main solutions through laboratory tests and to propose proven solutions. Many tests performed at NRC could have been avoided. Performing tests is expensive, and it would be interesting to make the link between the test results and the modeling results. Having a solution guide is great, but having a model that would predict the behavior of a design would be even better.
