The sound control requirements established by the National Building Code of Canada 2015 (NBCC) and other codes don’t have to be complicated.
Your solution for wall and wood floor assemblies? SilentFX® laminated gypsum board paired with noise-reducing insulation. National Research Council tested the combination and when used together the wall construction met code requirements for both fire and sound, no concrete required.
Figure 1: Example of NRC test assembly used to calculate Apparent Sound Transmission Class (ASTC) rating of 47 meeting NBCC and addressing flanking path
Reducing Noise in Tall Timber Buildings
Multi-unit wood and tall timber buildings are growing in popularity. Wood structures are easier to assemble, less noisy during the construction process, and produce less waste, Natural Resources Canada reports. However, for all their advantages sound transfer between units can be an issue. To ensure a comfortable living environment for all occupants code-tested systems should be followed.
Concrete Toppings vs. Noise-Reducing Gypsum
One way to meet code requirements in your wall assembly is to add a concrete topping. However, the use of wet, heavy concrete material in mid-rise wood and tall timber structures may not be the best approach due to multiple risks. These risks include the need for proper preparation, labour intensity, potential water damage, additional time for drying, and concrete cracking.
An alternative solution tested by the National Research Council (NRC) of Canada to meet both sound transmission and fire ratings in a multi-unit wood construction is to use noise-reducing gypsum board and fibreglass insulation in floors without a concrete topping.
How to meet NBCC sound control requirements without a concrete topper:
- Fill the wall cavity with a noise-reducing sustainable insulation. Fiberglass insulation in interior walls and floors/ceilings can improve sound reduction between spaces by 5 to 15 decibels1.
- Cover the insulated walls with laminated gypsum board technology, like that used in SilentFX QuickCut noise-reducing drywall. This drywall features a viscoelastic polymer between two specially formulated dense gypsum cores to significantly improve sound attenuation. It is ideal for systems requiring high STC performance
When executed as described above, this efficient option lessens install times, reduces labour costs and performs well acoustically over an extended range of frequencies. This results in an improved living and working space for occupants.
In addition, this combination has been found to effectively reduce noise pollution between units and when used with a Type-C face layer the insulation/drywall combination provides a fire-rated floor without concrete.