Ducts that end in the attic

Air ducts take air from one place to another (fun fact, duct comes from the Latin word ducere which means "to lead").

You have ducts attached to your furnace and air conditioning systems to lead hot/cold air from the appliance into the rooms in your home. Ducts wind through the walls and floors to pump cool refreshing air out of one of these. If you want to sound really smart, start calling them floor registers.

Other appliances use ductwork to pump air out of your home. Maybe you've got a hood above your stove top, or a clothing dryer inside your home. Both of these will connect to ducts that will lead stinky, humid, or hot air to the outside of your home.

At least they're supposed to.

On a recent inspection of a brand new construction home, I found this in an attic. That metal tube in the background is a duct that ends in the attic. Connecting a dryer to that duct means pumping your attic full of hot, moist air.

That leads to moisture in your attic.

That leads to mold in your attic.

And that leads to you getting sick.