The following is a response I wrote to the question "What can unit-owners in highrise condos do about odour transfer" for CCI Toronto.
Odour transfer in high-rise buildings is a frustrating reality. While the building mechanical design incorporates some features intended to minimize odour transfer, such as pressurized corridors, this design methodology is far from perfect and there is inevitably some odour transfer that cannot be prevented.
If an owner experiences odours in their suite, they should do a little investigation of their own to gather information before contacting management. This will help to identify if the smells represent a deficiency that can be repaired, or if they are experiencing normal conditions. This will help prevent false expectations and minimize unit-owner frustration.
Odour coming in around the entrance door from the corridor can relate to a variety of causes:
- Make-up air unit not operating (or providing an insufficient amount outdoor air) so the corridor is not sufficiently pressurized. This allows odours from one suite to travel into the corridor and then into other suites. Repairing or rebalancing the make-up air should help.
- Strong odours can leave one suite and enter other suites even when the corridor is adequately pressurized. The only solution here is to ask Management to make sure that the odour generator is running their exhaust fan to minimize odours. If they are, then residual odour transfer through the corridor would unfortunately be considered normal.
- Strong winds, exterior temperature extremes, open windows, and excessive exhaust can impact pressure in the building causing some odour transfer that wouldn’t happen under normal conditions. This should only happen sporadically and is considered normal. Make-up air unit drawing in odours from the exterior and pumping it into the corridors. In this case, the odour would be present on all floors of the building. The solution is to ask Management to try to relocate the source of the odour or the intake for the unit, if possible.
Odour coming in through your bathroom or kitchen exhaust generally indicates an outdoor source. A neighbour may be smoking or cooking on their balcony or smells may be being exhausted from one suite and then drawn back into yours. Typically the back-draft damper on the exhaust fan outlet (at the exterior wall) will be found to be sticking open. This allows air to travel backwards through your exhaust ductwork and into your unit. A sticking back-draft damper can be repaired. This may be a unit-owner or a Corporation responsibility depending on your declaration. If odours still penetrate when the damper is fixed, the best solution is to run the fan when the offending odour occurs so the air is flowing outward instead of inward.
Odours in other areas of your suite (away from the bathroom exhaust, kitchen exhaust hood, and away from the corridor door) generally indicate transfer through a floor or wall. These floors and walls are also fire separations, so they should be continuous and incorporate “smoke seals” (which are also “odour seals”) in buildings constructed after 1990. In this case, the odour transfer may also indicate a breach of the fire separation. Typically property management will need to hire a consultant to do a pressurized smoke test to determine the source of this type of odour transfer. Pre 1990 buildings had fire-stopping without smoke sealing, so unfortunately, odour transfer across these walls or floors would be considered normal.
The number one source of odour complaints is cigarette smoke. The easiest way to prevent this particular odour transfer is to create non-smoking buildings. The builders are reluctant to do this because they think they are limiting the size of their purchaser marketplace. Interested condo owners should petition the builders to start creating non-smoking condominiums (like one built in Ottawa). Contrary to their concerns, it is highly likely that they would have a waiting list of purchasers wanting to live in a non-smoking building rather than a shortage of buyers.