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Ducts · Install & RerouteDryer Vent Installation & Rerouting
Dryer vent installation and rerouting means running rigid 100 mm (4 in.) metal duct from the dryer to an exterior hood by the shortest route the house allows, with taped joints and as few elbows as possible. The rule that decides the route is the maximum vent length in the dryer's installation manual: every elbow uses up part of it, and a run that exceeds it will never dry clothes properly however often it is cleaned. There is no flat price; the written quote depends on the length, the finishes that have to be opened and where the vent exits.
The duct that belongs inside a wall, floor or ceiling is rigid metal: 100 mm (4 in.) round, galvanized steel or aluminum, smooth on the inside. Joints are fitted so the upstream piece sits inside the downstream one, then sealed with foil tape. No screws go through into the airstream, because every screw tip is a hook that collects lint. Foil or semi-rigid flex is only the short, visible transition between the dryer and the wall connection, and dryer manufacturers tell you not to use plastic or vinyl flex at all.
Every dryer has a maximum vent length in its installation manual, and that table governs the job. Each 90-degree elbow is counted as extra length, so a run with four elbows may be allowed only a fraction of the distance a straight one is. We measure the proposed route, count the fittings, and compare the total with the manual for your model before cutting a hole. If the numbers do not work, the answer is a different route or a different exit point, not a longer duct and hope.
Outside, the duct ends at a hood with a damper that opens under airflow and closes when the dryer stops, which keeps cold air, rain and birds out. The hood must not have a screen: mesh clogs with lint in weeks and turns the termination into a plug. Under the Ontario Building Code a dryer exhausts outdoors through its own duct, never into an attic, garage or crawlspace and never tied into a bathroom or kitchen fan duct. We also keep the hood clear of the gas meter, opening windows and the furnace's air intake.
Rerouting is the common call: a laundry room moved from the basement to the main or second floor, a renovation that boxed in the old duct, or a builder's run that wanders through three joist bays. Where a section passes through an unheated attic it is insulated so the moist exhaust does not condense and run back toward the dryer. A gas dryer raises the stakes, because its vent carries combustion products, carbon monoxide included, along with the lint and moisture. A disconnected or crushed vent on a gas dryer is a safety defect, and moving the gas connection is work for a TSSA-licensed technician — see gas dryer installation.
Install a new vent or reroute when
- The laundry room is moving, or a renovation has covered or cut the existing duct
- The concealed run is foil or plastic flex end to end, sagging, crushed or held together with cloth duct tape
- Dry times stay long after a full dryer vent cleaning — the route is too long or has too many elbows
- The vent ends in the attic, garage, crawlspace or soffit cavity instead of outdoors
- The exterior hood has a screen, a missing flap, or sits beside a window, an air intake or the gas meter
How it works
We look at where the dryer will sit, find the shortest path to an outside wall or the roof, count the elbows and check the total against the maximum length for your dryer model. You get a written quote with the route described — send us the laundry location and dryer model to start.
The opening is cut or cored, rigid 100 mm duct is run and supported along its length, joints are foil-taped with no screws inside the pipe, and a dampered, screenless hood is sealed to the wall or roof.
The dryer is joined to the wall connection with a short metal transition, pushed back without crushing it, and run so we can confirm strong airflow at the hood. On a gas dryer the gas connection is leak-tested as well.
Common questions
How long can a dryer vent be?
As long as the dryer's installation manual allows and no longer. Manufacturers publish a maximum for rigid metal duct and reduce it for every elbow, and the figure differs by model and by hood type. Have the model number ready, or let us read it off the door frame, and we will tell you whether the route you want is inside the limit before any work starts.
Can a dryer vent go through the roof?
Yes, when no wall route works, as with interior townhouse units and some second-floor laundry rooms. A roof exit needs a dryer-rated roof cap with a damper and no screen, insulated duct through the attic, and flashing done properly so it does not leak. Vertical runs collect lint at the cap, so plan on cleaning them more often — many people pair it with a duct cleaning visit.
Can I vent a dryer into the garage or attic?
No. A dryer puts litres of water vapour and a steady stream of lint into wherever it exhausts, which means mould and wet insulation in an attic and a lint-coated garage. With a gas dryer it also means combustion products in an enclosed space. The vent has to end outdoors at its own hood, and that is the first thing we correct.
How much does it cost to install or reroute a dryer vent?
It is priced per job, in writing, after we see the route. The drivers are the length of rigid duct, the number of elbows, whether ceilings or walls are finished, what the exterior wall is made of (coring brick takes longer than cutting siding), a wall or roof exit, and whether a gas connection moves too. Published bands for our other work are on the pricing page.
Does a condo or townhouse need approval for a new vent?
Usually yes. A new opening in an exterior wall or roof is a change to the common elements in most condominium corporations, so the board or property manager has to sign off before we cut. Freehold houses do not have that step. We can give you a written scope and a description of the termination to send with your request.