Duplex shares dryer vent exit - tenant complaints

[Leo Singer]

I am running into issues with a current tenant and wondering if anyone has had a similar issues? I also am curious as to how others would handle.

I am house-hacking a duplex and the 2 units share a dryer vent duct exit through the roof. When using the dryer the hot air exits into the other unit as well as through the roof. I have had the dryer ducts professionally cleaned and it is still an issue.  The tenant is becoming increasingly frustrated.  Have any of you ran into this? If so, how did you handle, or how would you handle?

[Mike McCarthy]

@Leo Singer I don’t believe a shared dryer vent is code compliant, mostly for the reason you specify.

What kind of roof? Is there attic access?

Seems like it would be a pretty cheap solution to just add a second vent through the roof.

Other option might be to add a spring damper, that will basically seal off one line when it’s not in use - similar to what you’d see on the actual vent hood.