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How to install a dryer vent
What's the best way to put a dryer vent through the exterior brick wall of my house? I don't know how to cut a big, round hole through this material. - Ravi Shah, Thornhill, Ont.
There are a couple of things to think about, beyond the obvious challenge of how to get through that brick. One of the main issues involves installing a vent pipe in a way that’s easily removable later, for replacement, while also keeping out rain and preventing air leaks and condensation within the wall cavity during winter.
The trick is to install not just one pipe but two. Typical dryer vents are 4″ in diameter, but instead of putting this pipe through the wall on its own, I recommend starting with a larger 5″-diameter galvanized steel pipe. Seal this pipe where it meets both the interior and exterior wall surfaces, then install the dryer vent through it.
Start work by determining the location of the wall studs in the area where you want the vent to be. Naturally, you’ll need to choose a spot where no stud exists and where wires are unlikely to be found. The zone within 8″ of the floor is usually free of wires; however, you’ll want to cut a careful exploratory inspection hole through the drywall to get a peek into the wall cavity, just to make sure.
If all looks good, rent or borrow a rotary hammer spinning a 1/2″ drill bit. This powerful electrical tool combines rotation and percussion to drill quickly through masonry. Bore a hole in the centre of the spot where you want your vent pipe to be, beginning inside the house and boring outward through the brick. (This same technique applies to houses with vinyl or aluminum siding, although you don’t need a rotary hammer. A regular drill with a long spade bit works fine.Next, go outside and use a felt-tip marker to draw a 5″-diameter circle centred on the hole that you just popped through the brick. You must cut out this circle to accommodate the 5″ pipe. You could use a coring bit to create a nice, clean hole in one go, although these can be expensive to rent.
Alternatively, bore a series of 1/2″-diameter holes all around the inner edge of the circle, as close as possible to each other, then use a 2-lb. hammer and a cold chisel to chip out the brick and clean up the edges of the hole.
Assemble a length of 5″-diameter pipe long enough to go through the wall (with aluminum tape applied to the pipe’s joint), then use a drywall saw to create a 5″-diameter opening in the interior wall. As you work, make this hole so the pipe will slope slightly downward and outward when installed–to allow incidental water to drain. Install the pipe, use a level to check its slope (give it about half a bubble), then use expanding foam to seal the interior wall surface and exterior caulking to seal around the outside.
Install the dryer vent louvre and pipe next. Set this unit into the opening from the outside, using lengths of foam backer rod or 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 foam between the two pipes into these 1″ gaps, then let it set. You’re now ready to hook up your dryer to a pipe you can count on or take apart later if necessary.