This report documents apparent/field impact insulation class (AIIC/FIIC) ratings and apparent/field sound transmission class (ASTC/FSTC) ratings for a large number of light-frame wood-joisted floors, cross-laminated timber floors (CLT), massive glulam floors, and a wood-concrete composite floor. The report includes various construction details involving finishings, membranes under finishings, toppings, underlayment materials for toppings, and drywall ceilings. This report also documents ASTC/FSTC ratings for some light-frame wood stud walls and CLT walls.
The AIIC/FIIC and ASTC/FSTC floor ratings were measured either in mock-up of two-story wood buildings, located in the structure laboratory in FPInnovations’ Quebec lab, or in wood buildings. The ASTC/FSTC wall ratings were measured in a mock-up of a side by side duplex of an FPInnovations member company, and its partner, or were measured in wood buildings. All measurements were performed in accordance with ASTM standard test methods for field sound insulation performance of floors and walls.
The informal subjective evaluation of field floors and walls by FPInnovations staff, and by occupants, revealed that, if a FSTC or FIIC rating is below 45, occupants could clearly hear sound generated by their neighbor’s normal activities. If a FSTC or FIIC rating is above 50, occupants could still hear "muffled" sound generated by their neighbor’s normal activities, but do not hear it as clearly. If a FSTC or FIIC rating is above 60, occupants could not hear any sound generated by their neighbor’s activities, except when there is a lightweight floor with a carpet. In that case, low frequency footsteps could be heard even if the FIIC was above 60.
Based on the findings from this study, it is concluded that, with proper design and onsite flanking control, wood buildings may achieve satisfactory sound insulation at a reasonable cost, as demonstrated in the report. It should be noted, however that:
§ most of the solutions presented in this report had a ASTC/FSTC or AIIC/FIIC rating above 45;
§ for light-frame wood-joisted floors, with good flanking control, to achieve FSTC/ASTC and FIIC/AIIC rating above 50, a decoupled drywall ceiling and a properly designed four-layer sandwich above the floor were required. The sandwich was composed of a finishing, membrane, topping, and underlayment;
§ for both 175mm CLT floors and 89 mm glulam floors without decoupled ceilings, to achieve FSTC/ASTC and FIIC/AIIC ratings above 50 is a challenge. It requires an intelligently designed four-layer sandwich topping on the CLT floors, and knowledge of the sound insulation performance of the finishing, membrane, topping, and underlayment, which is provided in this report. With a dropped acoustic ceiling, using acoustic hangers, it was relatively easy to achieve FSTC/ASTC and FIIC/AIIC ratings above 50;
§ a wood-concrete composite floor with a 100 mm thick heavy concrete slab bonded to a 89mm-wood deck can achieve FSTC/ASTC and FIIC/AIIC ratings above 50 quite easily, without requiring a dropped ceiling. Such composite floors were the simplest wood floor systems studied so far. The floor was composed of only four layers: the finishing, concrete, insulator, and wood slab, but it achieved satisfactory sound insulation. This is an attractive approach for sound insulation design of wood slab floors with wood exposed on the ceiling side.
However, it must be emphasized that:
§ when selecting a solution, a trade-off is required, which takes into account the sound insulation, material and labour costs, ease of installation, and impact on other performance aspects, such as those related to deformation, fire, thermal insulation, and structural integrity;
§ to successfully apply solutions provided in this report to building projects, there must be onsite quality control pertaining to flanking. The solutions cannot guarantee the same ratings if best practices are not followed;
§ best practices are comprised of three components: a) flanking control, b) field measurement of FSTC/ASTC and FIIC/AIIC ratings of floors and walls after a project is completed, c) subjective evaluations by promoters, developers, architects, engineers, and producers, using procedure provided in this report. If you do not like the sound insulation, you cannot expect occupants to like it either;
§ when using wood fibreboard as underlayment, caution should be used when selecting wood fibreboard. Its density and dynamic stiffness should be taken into account. Wood fibreboard products in the market vary greatly in terms of their density, dynamic stiffness, and their damping ratios. It is preferable to have a density higher than 3.5 kg/m2 and a dynamic stiffness lower than 90 MN/m3 for a 38mm concrete topping. For thicker and heavier toppings than the 38mm concrete topping, it is recommended to use thicker and heavier wood fiberboard with lower dynamic stiffness than that used for the 38mm concrete topping;
§ when using cementitious materials as topping materials, caution should be exercised. At the very least, their density, stiffness, and surface hardness should be known;
§ The ratings measured on the floors topped with 1.2 m by 1.2 m sandwich patches show trends pertaining to the effects of finishings, membranes, toppings, and underlayment materials on impact sound insulation. There is no quantifiable relationship between ratings of floors topped with 1.2 m by 1.2 m patches and the ratings of the same floors topped with full-size same patches. Therefore, ratings measured on floors with a 1.2 m by 1.2 m patch cannot be used to estimate the impact sound insulation performance of field floors fully covered with same patches;
§ The performance of various finishings, membranes, toppings, and underlayment materials studied and presented in this report is unbiased scientific data. There is no intention to promote or demote any product.
Further studies will be conducted to measure the acoustic properties of insulation materials in the market. Those studies will be used to guide the application of solutions described in this report.