Installing a Dryer Vent the Right Way

As do-it-yourself jobs go, installing a new dryer vent doesn’t look complicated, but there’s a lot more to it than meets the eye. At least if you want to do things right, that is. It’s one thing to punch some kind of pipe through an exterior wall, but quite another so the installation ages gracefully and doesn’t encourage wintertime condensation inside your wall frame.

Two to Tango: Dryer Vent Tip

The trick to making all this happen involves the installation of not just one pipe, but two. Typical dryer vents are 4″ in diameter, but instead of putting this single pipe through the wall on its own, I recommend starting with a larger, 5″ diameter galvanized steel pipe first. Available at all hardware stores, this pipe gets sealed where it meets both interior and exterior wall surfaces, with the actual dryer vent pipe going through this outer pipe.

Location, Location, Location

Start work by determining the location of vertical wooden wall frame members (called studs) in the area where you want the vent to be. You’ll need to choose a spot where no studs exist and where wires are unlikely to be found. The zone within 8″ of the floor is usually free of wires, though you’ll want to cut a careful, exploratory inspection hole through the drywall first, to get a peek into the wall cavity. An electronic stud sensor is pretty good at finding wall studs, but double check your proposed hole location by driving finishing nails through the drywall before cutting. This nail shouldn’t hit anything solid after penetrating the drywall.

dryer_vent_drillingDrill Away

If you’re well away from wood and wires, grab an electric drill and install a 1/2″ diameter drill bit in it. You’ll use this to bore a hole right through your wall, but if the outside of your house is brick or stone, you’ll need to rent a special drill called a rotary hammer with a matching bit. It combines rotation and percussion to bore through masonry quickly. A regular electric drill is fine for all non-masonry exterior walls. Either way, bore a hole in the center of the spot where you want your vent pipe to be, beginning inside the house and boring outwards.

Coming Full Circle

Next, go outside and use a felt tip marker to draw a 5” diameter circle centered around the hole that just surfaced. This is for the outer pipe you’ll be installing first, and how you actually create this hole depends on what the outside of your exterior walls are made of. If it’s masonry, then something called a coring bit for that rotary hammer you rented works best. It removes a nice, neat plug of masonry that’s 5” in diameter. If you’re dealing with non-wood siding, cut through the vinyl or aluminum with multiple strokes from a sharp utility knife, then bore a series of 1/2″ diameter holes all around the edge of the circle, as closely as possible to each other, right through the internal wall sheathing. Finish up with a jigsaw or reciprocating saw to remove the wooden disk.


Perfect Piping

Now’s the time to install the 5” diameter outer pipe. All hardware stores carry them, and you’ll need a piece long enough to go through the entire wall thickness. As you set this pipe into position, make it slope slightly downwards and outwards when installed. Use a level to verify the outward slope of the pipe, then use expanding foam to seal the interior wall surface and exterior caulking to seal outside.

Final Step: Vent Installation

Installation of your actual dryer vent louver and pipe comes next. Set it into the opening from the outside, using small chunks of foam to support the pipe evenly all the way around, about 1” back from both the interior and exterior wall surfaces. Shoot a small amount of expanding spray foam between the two pipes, then let it set. You’re now ready to hook up your dryer to a pipe you can count on.

Posted on March 15th, 2011