Venting a spray room--Your thoughts please.

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Blog entry by eastside posted 01-25-2010 03:13 PM 2438 reads 0 times favorited 6 comments Add to Favorites Watch

I’m building a spray room today in my shop and need to exhaust the fumes but the explosion poof fans are very expensive. The cheapest one I could find is about $600 dollars. So this is what I planed and I’m looking for your impute, ideas and thoughts. My shop is in my basement so it is mostly underground. The size is 30 feet X 60 feet. I’m going to build a wall across the shop 30 foot and 15 feet off the wall leaving a room 15×30. Then cutting that in half leaving 2 rooms 15×15 with a divider wall. Each of those rooms have a window in them at the top of the wall ( basement window style). The height of these rooms are 9 feet 8 inches taller then average. In the divider wall I plan on cutting 2 holes towards the top of the wall the size of a basic window box fan and installing a filter in them. The fans will blow air INTO the paint room through the filter and across the room and exit out the open window on the other side of the room with a filter in that window. With the window up high and the fans also up high I hope the create a cross ventilation high enough not to be blowing directly on the project but enough to exhaust the fumes and some over spray. What do you think?

-- Mike, Westport MA.

6 comments so far

View Don Butler's profile

Don Butler

1092 posts in 3389 days

#1 posted 01-25-2010 04:09 PM

The idea is sound as long as the room is fairly well sealed. Be sure the make-up air is not sucking conditioned air out of the rest of the house.
Open another basement window with a filter over it to keep dirt out.
Another concern would be the overhead.
It might be good to place plastic film on the overhead in some way to prevent paint fumes from going through the floor of the first floor.
Since this design will be pressurizing the room to some extent it is important that fumes be contained inside and vented outside.
Plastic film on the walls and a good seal on the door will prevent sending fumes where they should not be.
A deflector of some design might minimize drafts going straight on the painted objects while still giving good ventilation in the room.
Another concern is the presence of a furnace and/or water heater in the basement. If the paints are volatile, there is the ever present danger of gas-fired appliances of causing an explosion.
Remember, too, what you vent outside will be a problem if the neighbors get it in their noses!
I had the experience of helping my son build a paint booth in his autobody repair shop. It was a treat.

best regards,


-- No trees were damaged in posting this message, but thousands of electrons were seriously inconvenienced.

View Moron's profile


5032 posts in 3887 days

#2 posted 01-25-2010 04:17 PM

something to watch for as I have seen this before

the suction can “snuff” out the pilot light on a furnace

fumes tend to creep along the floor, if you have a furnace, this can be dangerous

-- "Good artists borrow, great artists steal”…..Picasso

View ajosephg's profile


1880 posts in 3555 days

#3 posted 01-25-2010 04:18 PM

IMHO a box fan wouldn’t blow through a filter, much less two fiilters. I’d think you’d need some kind of squirrel cage fan.

I’m not a HVAC guy but I’d start by finding out how many CFM of air needs to be moved to provide adequate ventilation and go from there.

-- Joe

View eastside's profile


97 posts in 3255 days

#4 posted 01-25-2010 07:45 PM

Thanks guys, I put the framing up this morning and now its lunch time. My furnace takes the combustion able air from outside. When the house was built I had the plumber run PVC directly out side and connected to the furnace to keep it from sucking saw dust. I’ve been here 3 years now and not I single problem with that set up. Both of those rooms have windows and I was planning on opening up the windows when running the fans. Both rooms have their own entrance and the door will be an exterior metal door fully weather striped with the threshold to stop any air leakage. The ceiling in the paint room will be finished and both sides of the walls so I think I have the room contained. I am even going to put the light switch on the shop side of the wall to prevent a spark problem. The furnace is not in the paint room it is in the other room with the electrical panel. The 2 filters are for 2 fans not 2 filters in front of one fan. I have an old box fan kicking around somewhere so I’ll have to test if it will blow through a filter, I’m pretty sure it will but a good point. This is only going to be used when a project is finished and I guess about 10 minutes of spraying and done till the next coat so I’m not anticipating a problem with my neighbors and I live a little in the country my closest neighbors house is a good 150 feet away and then the next is 5 to 6 hundred feet away. I take this all as good news as nobody said it won’t work.

-- Mike, Westport MA.

View RichClark's profile


157 posts in 3424 days

#5 posted 01-28-2010 03:24 AM

There is allot of talk about “explosions” from fumes and the like out there… The motors you are noodling about make sparks as they spin. The chance for combustion is a complicated issue of amount of flammable gas and the Oxygen in the room. The best way to get your dream booth would be to mount a motor in a enclosure and use a belt to drive it. That is the “bad things happen” folks… I set up a simple curtain made of PVC and plastic drop cloths that faces a 2×3’ window with a old old sears fan on the sill and crack open the back door to pull the fumes out.. never had a problem..


-- Duct Tape is the Force! It has a light side and a dark side and it Binds the Universe together!

View a1Jim's profile (online now)


117086 posts in 3571 days

#6 posted 01-28-2010 03:35 AM

I say spend the $600 There are some places you can save money but this should not be one of them. How much will and explosion cost? Maybe blow you or your house up. The only alternative is to only spray water base stains and finishes.

-- wood crafting & woodworking classes

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