Ventilating parking garage


I’m currently in the process of bidding on a 120k sq ft low ceiling (approx. 6’2") underground garage with NO windows and limited exhaust system. I’m considering using a trailer with two 3500psi pwr washers, 2-8gal with heat. but I’m not coming up with a good plan to limit the CO concentration and make it a safe working environment.
If there are any ideas or input would certainly appreciate it.




You might want to message @JohnT about that…Parking garages are one of his main things. He’s not on here much anymore, but he’d probably respond if you reach out to him.


No experience with this, but longer hoses? Perhaps a long ventilation hose connected to both units? I know it would kinda suck when you have to move the trailer - perhaps it could have a screw on clamp to easily remove the vent hose, relocate the trailer and then reattached the vent hose.

What is the layout of the garage? One huge room, or several levels?

Fans? Is their power in the garage to connect to? Create a swamp cooler effect in that you have a fan at one end and then an opening at the other to create a draft that would catch the fumes and carry outside? Would take a large commercial port a cool type unit but you can rent those cheap.

Final option that comes to mind would be a mask/tank set-up similar to what firefighters use.

Lastly, get a portable CO2 detector so you can track levels to know if you are getting close to the danger zone or do what the miners did - get a canary and when it drops dead, get out.


I can’t help but think…

You said this was a parking garage. Meaning it is where you would park motor vehicles. Which produce lots of exhaust. Puzzles me how you would be worried about this in a place designed to drive vehicles in and out of. Surely there is enough ventilation for a day of pressure washing if cars regularly drive in and out. Maybe my redneck brain is missing something?


I would think so, But who knows on an old construction if they even worried about it then.

We recently bid on a parkiing garage that was also underground, and as I was doing the walk thru the manager of the place mentioned the garage having nox level sensors?? Once they reach a certain level the exhaust fans kick on sucking all the air out… Crazy but makes sense


Good point, But I think the concern is the duration and concentration of emitting exhaust. The parking garage is underground 4 levels and we’d be working for approx. 6hrs per floor. Not sure how to direct exhaust fumes into ventilation system? Industrial fans


You shouldn’t need to. You ever been to an indoor motocross race of any kind? Eyes may burn a bit but its not enough to kill you or really even make you sick. I agree that if cars are not causing an exhaust problem then your pw motor wont!


I would think you could tie both exhausts into a high flow catalytic converter. Most custom muffler shops could do this. In theory, that should convert most of your poisoness carbon monoxide into a less poisoness carbon dioxide. Get a decent carbon monoxide sniffer, and check it every so often.


Just pick you up a couple Canaries.