Turn exterior stairwell into spray booth?

[Eric DeSilva]

I've been reading the accumulated SMC knowledge on knockdown spray booths--my thought was to build one and set it up so the exhaust fan was exhausting out of my basement into the basement stairwell. Then I started thinking about just turning the stairwell into the spray booth. My basement has 9' ceilings, so the bottom of the stairwell has plenty of headroom. I'm thinking I could rig up a temporary "ceiling" for the stairwell with an exhaust fan just pointed into the back yard... With the door into the basement (it opens into the basement, not into the stairwell), I can put the object-to-be-sprayed in the stairwell itself, and stand in the basement or doorway. Anyone see any issues with exhausting things up rather than using a fan directly behind the object-to-be-sprayed? Seems like that is what exhaust hoods do... Any reason not to just leave the side with the stairs open?

And, on this topic, I'm using an Earlex 5000 and can't see myself using other than water-based products. What kind of fan should I be looking for--how many CFMs are needed to clear spray residue? I'm wondering if those high speed fans--look a bit like snails--for drying areas after they flood might work. I see those on CL for cheap a lot. I'd have to build something to seal the intake to my ceiling, obviously.

[phil harold]

I have always preferred the suction of a spray booth to be below and behind the work piece
Maybe you could add some duct work and use an old furnace fan

[John TenEyck]

You are still going to have to protect the walls, stairs, etc. from overspray. With that in mind, I don't see what the real benefit is compared to just setting up a temporary booth in your basement. I use nothing more than plastic sheeting hung over nails in the floor joists and old sheets on the floor. It takes less than 15 minutes to set up/take down everything. I also spray only WB products. I use my 1200 CFM dust collector fan as my exhaust fan, bypass the bags, and blow it out a window with no filters. Works great. Low tech, but very effective at removing overspray.

John

[Eric DeSilva]

I don't think I'm going to be spraying a lot of color, and I can always cover up the walls/stairs if I do. I don't think it will bother me to put some EM6000 on the walls of the stairwell.

But, maybe the foam panel knockdown booth is the right plan at the end of the day... Just jet it all out to the stairwell.