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Just about anyone who’s lived in a townhome or duplex has mixed feelings about their neighbours: maybe it’s the choice of music late at night, particularly pungent cooking, or even worries about fire safety. As it turns out, keeping on good terms with other residents depends heavily on the quality of construction in the “party wall” separating the units. 

In this video, Building Knowledge Canada President Gord Cooke describes the construction techniques that make multi-family buildings better for everyone. 

Gord: One of the most intriguing changes in airtightness for us at Building Knowledge Canada has been the amazing increase in the number of multi-family dwellings being built across Canada. It's roughly 60% of all new dwelling units—whether that's back-to-back, stacked towns, or row houses. And that adds complexity, because of the party wall. Technically, it's not an outside wall. It's insulated for fire and noise but from an airtightness perspective, we need to treat it like an outside wall. That means having a material that serves as the primary air barrier. 

The air barrier system of a common wall may consist of drywall, approved tapes and sealants, and most importantly a continuous air-resistant material through the assembly such as spun bonded poly oliphant (Tyvek). In some cases, a simple polyethylene sheet can be used to connect air barrier materials. 

Gord: There are various techniques and strategies. We enjoy helping builders work with their design and production staff to ensure that the party wall is as airtight as an exterior wall.

When a good air barrier is in place and good compartmentalization practices are applied, the sound reduction, odour resistance, and plain spread rating are all approved across the assembly. So, the compartmentalization of multi-family projects is super-important in the air-tightness world. For more information, you can view the National Research Council Canada’s study on these types of assemblies on our Air Barriers in Multifamily Low-Rise Housing: Are we placing Air Barriers in the RIGHT walls? webinar slides and recap. 

Clearly, building a party wall the right way can pay enormous dividends for many residents with different lifestyles and noise tolerances, over the life of a building. Through Building Knowledge Canada’s Builder 360° program, builders can learn how to make multi-family dwellings comfortable and agreeable for residents on both sides of a party wall and adapt other novel systems and technologies to optimize their housing designs.

Connect with us anytime, and let us know what outstanding questions you might have on this subject.