DIY Exhaust Fan for your Shop

Whether you’re looking to keep the air in your shop a little fresher, or you just want to keep the air moving so you stay a little cooler in the warm months, this DIY exhaust fan is for you. It’s so simple to build; taking advantage of simple box fans you can get from any home center or big box store.

Air Movement

I don’t know how many CFM this unit moves, but I can tell you this. When all three fans are running on high and a window at the other end of my shop is open, I can feel A LOT of air pouring in. How many CFM in a lot? A bunch. :) In other words, this simple system is really effective.

The Concept

Here’s the idea. We’re going to stack three box fans vertically to fill the frame of a service door in your shop. The fans themselves won’t fill the door frame, so you’ll have to build a flange assembly that makes up the difference. The tighter you get the fit, the better this will work.

The Build

Your DIY exhaust fan will be idiosyncratic to your door, so we can’t give you dimensions or a specific plan. I used plywood for the frame that surrounds the fans, and hardboard to create the flange that goes up against the door opening. Start by buying the fans, and build the frame and flange to work with them. Casters on the bottom facilitate moving the unit into and out of the door opening.

Our DIY exhaust fan is designed to move air out of your shop, while pulling fresh air in.