Thread: Condo venting??

I did a home inspection on a condo in a 10 unit 2 story structure. It was an old building that was newly renovated. I noticed while checking bathroom fan terminations at the exterior that there were only two terminations for the whole bldg. I also could not find the dryer vent terminations. The structure has a crawlspace and the subject property is on the first floor. I wrote up that further evaluation was necessary. The sellers response is that the terminations are on the outside of the bldg and it must have been an oversight by me. Well I looked pretty close and am confident that there are only 2 for the whole bldg. My question is, how many times(if any) can you join two or more ducts into one termination? The only way they are correct is if all 10 units are sharing the same termination. and that still doesn't get the dryers for every unit to the outside. I'm reinspecting the property on Tuesday with the seller and contractor(they may be the same person). I want to make sure I have an answer if he says in fact that all bathroom fans share the same termination. Thanks in advance for your input

Similar Threads:

• Condo common areas
• Venting for gas fireplace
• AFCI in conversion to condo
• condo panel box
• Combustion air venting location

This is why its helpful to take a full view picture of every elevation. Not slamming you, just an overall reminder.
As far as the dryer vents, I see common stack vents for multiple dryers in condo buildings somewhat regularly; not often but now and then. Usually 6" or 8", one per tier. Also seen these vents on approved Plans. Typically the ones I've seen run to the roof and have a clean out Tee downstairs. If you are seeing a 4" termination for multiples, I don't think that would comply out. If you are meeting with the owner and/or contractor then the obvious response is "Hi Sir, nice to meet you. Can I see the approved Plans with the mechanical page showing your exhaust pipe arrangement".
- dryers and bath fans cannot be combined into one, see M1502.1
- see M1506.2 for the bathroom exhaust, specifically states not into crawlspace
These are from the IRC. I need to buy another IBC since mine doesn't seem to want to come back home. Someone will probably have the IBC sections for you.
- I'm pretty sure I've read bath fan install docs that state they shouldn't be run together into combined exhaust pipe. This would be for your standard Broan, Panasonic contained motor units. Did you write down the make of the bath exhaust fan? If so, look it up and see what the install guide says.
- Now if this is a common vent system for the bathroom exhaust, either mechanical or draft, then one termination might work. But that's its own system and is unlikely to have individual fans units in each bath.
So in short the Seller/Contractor needs to prove out his system. New rehab, lets see the Plans. 4" pipe for multiple units, hammer him, too many potential problems for your client.

I'm sure it could be reduced to two main vent exits, but backdraft dampers and upsizing would be a part of that. I have no idea what the mechanical code would allow, ( require ), when you start adding multiple vents into one stack, but I am sure that stack would be substantially larger than a single unit size. Pretty tough to verify the backdraft dampers, but the size of the vent exits could be verified. Was there an attic space ?

Flat roof so I'm guessing no attic. Like I said the subject unit is bottom floor. I tried to get on the roof because I figured that is the only place they could go but my ladder was about 2 feet short. After the seller responded that they are on the outside wall, Im really scratching my head. There were other deficiencies that lead me to believe that most if not all the work was not inspected or approved. Part of their response with electrical issues was that it was inspected and approved by the municipal bldg inspector but I found no approved sticker on the panel and also no ground wire. Bedroom outlets were GFCI protected instead of AFCI and not all were on the protected circuit. Anyway I know the agent is nervous about it but I have some questions I want to get answered on Tuesday. Thanks for the help.

As Markus said, many condo buildings have risers for clothes dryers and bath exhaust fans, which means there would be a fresh air intake down low (such as at the first floor) and an exhaust discharge outlet up high (such as on the roof), and all clothes dryers connect to the clothes dryer riser and all bath fans connect to the bath fan exhaust riser. The exhaust fans for those typically run continuously, drawing air from each bathroom through the common riser and drawing air up the clothes dryer riser for when any dryer is operated.

Usually, the bath exhaust is just a grill in the ceiling with a limited cfm air movement as not much is required for continuous bathroom ventilation rates.

Originally Posted by Bill Anglin

My question is, how many times(if any) can you join two or more ducts into one termination?

Well, if you used a little ingenuity, probably a whole bunch - as many as you can possibly cram in.

We had an issue of powder room and dryer vents sharing a stack in our 1920s 6-flat condo. It took several years to talk the other owners into separating the two. There were plans on file with the city from 1993 for plumbing supply and waste lines for a bath and laundry, apparently venting bath and dryers wasn't enforced back then. The dryer vent contractor recommended that the existing 6" pipe continue to be used for the powder rooms, and that we use a 4" (smaller) pipe for the dryers to speed up draft. We have plastic damper doors where the flexible metal pipe meets the solid metal vertical pipe.