Technician setting up tools inside plastic containment. Example of the work involved; the photo does not show a specific property or a job for this site.
The basic idea: corridors are supposed to win
Most mid-rise and podium apartment buildings built in the last few decades supply outside air to the corridors through a dedicated unit on the roof. That air slightly pressurizes the hallways, so when there is a gap under an apartment door, air flows from the corridor into the unit and leaves through the bath and kitchen exhausts. Odor from inside the unit stays in the unit.
When the corridor air unit is off, filters are clogged, a damper is stuck, or someone has set the system back to save energy, that pressure can drop. Now the units, with their own exhaust fans and heating, may push air the other way. Residents describe it as the hallway smelling like someone's dinner or cigarettes, and it is often worst near elevators and stairwells where air collects.
Terms worth knowing before you call a mechanical contractor
- Corridor make-up air
- Outside air delivered to hallways, usually by a rooftop unit, to replace air exhausted from apartments.
- Pressurization
- Keeping one space at slightly higher air pressure than another so air flows in a chosen direction.
- Door undercut
- The gap under an apartment entry door, sometimes intentional to let corridor air reach the unit.
- Test and balance
- A report from a balancing contractor showing measured airflows compared with the design.
- Stack effect
- Warm air rising through a building, which pushes air out at the top and pulls it in at the bottom, strongest in cold weather.
What site staff can check without tools
- Is the corridor supply unit on the roof running, and when were its filters last changed?
- Do corridor supply grilles have airflow you can feel with the back of a hand?
- Hold a tissue at the bottom of a unit door: does it get pulled in toward the unit or pushed out to the hallway?
- Are stairwell doors held open, which can short-circuit the corridor air?
- Did complaints begin after a cold snap, a roof unit repair, or a change in the building automation schedule?
What to do with what you find
- IfCorridor unit is off or filters are badly loadedRestore operation and filter service first, then wait a few days before chasing other causes.
- IfAir flows out of one unit onlyThat unit may have an exhaust or door seal issue, or heavy indoor smoking; address the unit and consider door sweeps and weatherstripping.
- IfAir flows out of many units on the top floors in winterStack effect is likely; ask a mechanical contractor to review the original balance report.
- IfNobody can find the original balance reportAsk for a new test and balance on corridor systems before buying sealing products by the case.
General information for Centennial, not a quote or professional advice. In an emergency, call 911.