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Clothes dryer exhaust connected to the bathroom ventilation shaft

0 votes
LeeSa says:
February 18, 2011 at 8:40 am

The 8 floor apartment building in which I live, which was constructed in 1972, has a single ventilator shaft that draws air out of all bathrooms in each tier (i.e.the apartments with identical floor plans that are stacked one on top of the other from first floor to 8th).

When the tentants of the apartment directly above me (I am on first floor and they on the second floor) installed a laundry dryer in their bathroom, which is directly above mine, the management connected the dryer exhaust to the ventilation shaft that connects both apartments. Because the motor on this dryer is powerful, their clothes dryer now discharges dryer exhaust downward into my bathroom!

Does this violate a building code? Does building code permit using a bathroom ventilator shaft for exhausting everything that comes out of an electric clothes dryer?

Any suggestions?

asked in Laundry Area by darekrudy (21,730 points)
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1 Answer

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Hi LeeSa

I can't really answer your question because there are several variables responsible for the dryer vent discharging into a ventilation shaft being code compliant or not. This "investigation" would most likely have go back to the building drawing mechanical blueprints.

There are several rules that may or may not apply to your condo and may or may not be enforced by your local jurisdiction. The best way would be to contact your local building department and describe this entire situation.

Although, dryer vent installations are permitted in some multi-unit / high-rise buildings (and jurisdictions), the ventilation system MUST be designed to properly handle it. Yours could require retro-fitting, and that's why your experiencing back-drafts from the dryer above.

Some of the requirements for the common ventilation shaft are:

  • material type (in most cases 26 gage or 30 gage sheet metal / smooth wall)
  • joint types (air tight / no screws shall penetrate walls to prevent lint accumulation)
  • proper fire rating of the shaft
  • adequate diameter to accommodate multiple appliances
  • access for lint cleaning (often top and bottom of the shaft)
  • booster motor on the roof (sometimes more than one) equipped with sensor detecting air pressure changes - usually they operate constantly on a low speed and accelerate whenever the dryer starts operating, dryer connections cannot be on the same level / across from each other, etc.

In case you'll get a negative response from the building department (claiming this installation illegal) you could suggest the association to require condo owners to use condensing type clothes dryers (they require condensate drain installation)

Let me know if you have any other questions.

answered by darekrudy (21,730 points)
Jason says:


No it is not to code in any way shape or form. A clothes dryer vent must be vented to the outside of the building and can not travel more than 14 feet if the duct has (2) two 90º bends (just coming out the back of a dryer counts as one bend and for sure there is another to get into the ventilation duct). That vent duct is way too long to be within the 14' requirement …

Furthermore it is not to be used for a dryer duct under ANY circumstances to begin with. And most importantly of all a GAS dryer (not electric) exhausts CARBON MONOXIDE which is lethal. Sounds like the ‘handymen’ they hired just wanted to get out & get paid.

Even if your neighbors clothes dryer is an electric model (not gas) there is still the issue of lint build up and possible fire hazard. IF their dryer is GAS then I would say you have a hell of a lawsuit against the building owner and with your settlement you should have a nice down payment on your new home.
Hi Jason,

Your information about clothes dryer venting is correct but it applies to residential installations. The rules / code is slightly different for multi unit buildings / high-risers.