I vent my 2 laser exhausts through the ceiling at my office…it goes 12 ft above the drop ceiling (which is 8 ft) up to the roof. ( total of 20 ft). I have a large exhaust fan enclosed in a box with vents sitting on the roof that pulls the exhaust up and out.
You will need a fan to help the exhaust along and make sure it vents out and not into the crawl space. I have a blast door slider on the hose so cold air doesnt filter down to the lasers in the winter too.
There is a math formula that determines how much fan you’ll need vs the length of your venting…I dont have that handy atm…