Question on DIY darkroom ventilation

[MILC Toast]

I don't know where you are but in the USA, I would just wait for election day and recycle political signs to make darkroom walls. Get some cheap rough cut 1x4" lumber to make your frame, a handful of screws, a staple gun and tape to put it together and make it light tight. Then a door or curtain of some type. Plumb your ventilation on the exterior and you'll have easy to clean interior surfaces that don't collect dust.

[domaz]

I was trying to avoid building out a separate room due to the complications. Given the open floor joists I think I would need a ceiling in it to make it fairly air tight so a ventilation fan can do its job. I have gone to the effort of light sealing the large space and it seems to work fine ( and I have learned that distant small light sources are not really a problem.

I guess this big space also reduces the importance of complex venting. Right now I am not standing directly over the trays and the smells don’t bother me at all. I’m just worried that longer term it might be a problem, but limiting my printing to B&W probably means I may be excessively cautious.
With that said - I did consider a quick way to wall off a room and haven’t totally abandoned it - it is called tge “Ever Block” system.

https://www.everblocksystems.com/our...caAiuIEALw_wcB

I solved the open floor joist problem in my darkroom by cutting small sheets of drywall to fit between each joist. They will never exactly fit so I then filled the gaps with expanding foam which I cut flush with the drywall once it sets. Just using a sheet of drywall for a ceiling is of course the proper way- but that would have been extremely difficult in my old house where the joists do not sit evenly and are all of a slightly different size.