One of the most common sets of defects I find during home inspections involve dryer vents. I see the wrong materials used in the wrong ways constantly. Since a vent full of lint can burn down your house, let’s talk about the right way to do it.
There are 3 basic components I look for during a home inspection. The first is the flexible vent extension that connects to the dryer itself. This is where I see the most problems, the most common being the use of flexible “foil” duct. I put foil in quotes because it’s really aluminized plastic or Mylar, the same stuff used in shiny balloons. It’s not intended for high heat applications and can melt and burn. Funny thing about dryers, they get hot. The correct style of duct is a flexible aluminum; it looks a lot like a disposable pie pan. Finally, you want to be sure to use the shortest length possible so you don’t end up with a tight bend in the duct, as in the above picture. That sort of thing creates a trap for lint.
From there, whether it’s inside the walls or visible, we want a solid metal duct, no more than 25’ in length, reduced in length by 5’ for each 90 degree bend. Lastly, the duct should be connected with foil tape only, no screws; they create another place for lint to gather. It’s often hard to see this during an inspection, since the vent is often concealed in the wall.
At the end of the run, on the outside of the building, we need a vent cap. It should have a hinged metal flap to prevent air from coming back into the house when the dryer’s not running. Screens are not recommended as they; say it with me “trap lint”.
And the last word is: clean your dryer vent. The Nation Fire Protection Association reports that in 2010 16,800 fires started in laundry rooms and of those, 32% were caused by failure to clean the vent. For more information, check out their article here. I recommend you check the flexible vent monthly for lint build-up and vacuum the rigid vent twice a year.