Grow room renovation advice

I have been asked to renovate a grow room for a client. This room was used to grow fodder but was never taken care of. The walls are a rough plywood painted with a semi gloss. I have to re-slope the floor and cut ditches to the two center drains. Ill need to install new dehumidifiers and some kind of exhaust. The room is used in the dead of winter where outside temperature is -20. Anyone have any advice on How to tackle the walls? I was thinking bleach scrub wash . Prime with killz. And either top coat with epoxy. Or wrap the room in plastic. They want the room to function better. Right now they have no exhaust cause of the freezing temperatures so the room is always at 100 humidity. Any advice is greatly appreciated.

Wash with TSP before painting is what I would do. When you paint use something with a mildew blocker in it but low VOC.

Phoenix, Quest and Fantech all make good commercial dehumidifiers.

Do they have a CO2 generator? That will add some heat but also humidity.

They make those HVAC heat exchangers for fresh air intake. They use the exhausted warm air to bring the intake air up in temperature a little. You could implement one of those on an intake to get a little fresh air for CO2 if they aren't going to run a CO2 generator. Wouldn't require a lot of CFM to keep it at ambient and the fans could be run on a CO2 controller.