• Welcome to The Building Code Forum

    Your premier resource for building code knowledge.

    This forum remains free to the public thanks to the generous support of our Sawhorse Members and Corporate Sponsors. Their contributions help keep this community thriving and accessible.

    Want enhanced access to expert discussions and exclusive features? Learn more about the benefits here.

    Ready to upgrade? Log in and upgrade now.

Apartment building common dryer exhaust

A

amarshall

REGISTERED
Joined
Nov 28, 2022
Messages
9
Location
Bloomington, IL
Hello, I am a city mechanical inspector. I received a complaint about an apartment building and had to go through and look at all their in-house lovely work. I went and had a huge list for corrections on the heating and cooling side. The laundry I went through has 4 dryers with the exhaust tied into one 4" hard piped exhaust. I looked in the mechanical code and IMC 504.10. So, if I am understanding it will need an exhaust fan that runs continuous. I would assume would need a common duct of at least 6" but is there some documentation or table to pull that off of?
 
Can the manufacturer's instructions for the dryers be located? I'm not seeing a sizing table anywhere, but 504.11 (2021 IMC) refers to the duct being "designed". If you could get a CFM for each dryer, maybe you could size the fan and common duct according to that as an objective way to approve or disapprove the design?
 
504.10 applies to the large commercial type dryers seen in laundromats or hotel linen laundries. If it looks like a dryer you would have in your house (minus the coin slots) its a domestic dryer, not a commercial dryer. A dead giveaway is the size of the exhaust outlet. If it's 4", its 99.9% chance its a domestic dryer. If the duct connection is larger than 4" its a commercial dryer.

If these are residential dryers, they can't be tied together in a common duct and must be ducted out individually, unless they meet the requirements of 504.11 of ducting multiple dryers into a common shaft, but not sure that would even apply here.
 
Yup, just looked - our 504.11 is the same as your 504.10. They added the section karenbleek was talking about as 504.10 and bumped the old 504.10 to 504.11 in the 2021.
 
OK, yea that is what I was looking at so I am thinking I need to tell them they need to either vent all separate or vent in a bigger shaft supplied with exhaust motor and follow 504.10. or 504.11 in your case.
 
Keep in mind 504.10/504.11 applies to a rated shaft in a multistory building, involving subducts, a continuous 24/7 upward airflow using an explosion proof fan with a standby power source, and an alarm in case of system failure. Typically only seen in high rise buildings. This isn't intended as an out to connect a few dryers together. The cost of the requirements alone would prevent that....
 
I agree is why they should be installed with separate exhausts. If they insist on doing a common exhaust, I don't see another option besides 504.10/504.11
 
amarshall said:
I agree is why they should be installed with separate exhausts. If they insist on doing a common exhaust, I don't see another option besides 504.10/504.11
Click to expand...
Amarshal, your previous posts did not say whether the apartment building in question is multistory, which is key to the applicability of 504.10.
Is it multistory?
 
How long has it been in use? How long is the duct? Is there a build up of lint? Have you witnessed a brush passing through to see if it is clear? Is there maintenance staff? ....Not that it would matter but is there a rated separation between the laundry room and the apartments?
 
amarshall said:
I need to tell them they need to either vent all separate or vent in a bigger shaft supplied with exhaust motor and follow 504.10. or 504.11 in your case.
Click to expand...
I would tell the owners that the dryer exhaust doesn't meet code, and they need to hire an engineer to design a proper system.
 
The apartment complex has a history and last year one of the buildings caught on fire. It was not from dryer but from wiring. In past they have done most of their own maintenance and construction, but we have been cracking down on them doing work without permits and without qualified contractors. Complaint was from a resident that when the dryers were running that exhaust was being exhausted indoors. Electric dryers that are being vented outdoors but I stopped by and looked again yesterday 5 dryers often running at same time all connected to a single 4" exhaust pipe. The property group is one of those that will not do anything unless they have to. I am going to get the cfm of each dryer today so I can calculate the min duct size plus all the other requirements if they want to continue using a common dryer vent.
 
You must log in or register to reply here.
Back
Top