Dryer Vent Code in Quebec for Homeowners

The building chapter of Quebec’s Construction Code is the National Building Code of Canada with amendments for Quebec. The National Building Code says exhaust ducts connected to laundry drying equipment must discharge directly to the outdoors. Apartment buildings can use one central exhaust system for several dryers, but it has to be designed for that purpose.

For typical houses, the code does not provide one universal dryer vent length or duct specification. Duct size and length are left to the installation instructions of your dryer. The Montreal fire department fills part of the gap. On its household dryer safety page, it says dryers must vent only to the outside, that vents must be metal, as short and as straight as possible, and that no more than four elbows may be used unless the manufacturer’s instructions say otherwise. Which edition of the code applies depends on when your construction or renovation work began, so a contractor or the RBQ can confirm it for your project.

The maximum dryer vent length depends on your dryer’s installation manual. Many standard models allow somewhere between 25 and 35 feet of rigid duct, and some long vent models allow more, but the manual for your exact model is the only number that counts.

Every bend shortens what you are allowed. Installers commonly subtract about 5 feet for each 90 degree elbow and about 2.5 feet for each 45 degree elbow. This is why two homes with the same dryer model can have different maximum vent lengths depending on the duct route. This rule of thumb comes from US practice rather than from a Quebec article, but it is a sensible way to estimate. So if your manual allows 35 feet and your route needs two 90 degree elbows, you have roughly 25 feet of straight pipe left to work with.

Measure the path the air actually travels, including the vertical climb to a roof or a high wall exit. A laundry room in the middle of a house can use up the allowance faster than the floor plan suggests. When a route is too long, the best fix is a shorter, straighter route. A booster fan can help in some layouts, but only one made for dryer lint and accepted by your dryer’s manufacturer, ideally after a professional has looked at the run.

Smooth, rigid metal, either aluminum or galvanized steel. A smooth wall gives lint nothing to catch on. Plastic and vinyl ducts do not belong on a dryer at all, since they can melt and their ridges trap lint. Foil flex duct has the same lint problem, so it should not be used through walls, ceilings or long duct runs.

A short flexible metal connector is acceptable between the back of the dryer and the wall, as long as it stays visible and is not buried behind drywall. Seal the joints with metal foil tape and point them in the direction of the airflow. Avoid screws that stick into the pipe, because each tip collects lint and shrinks the opening a little more each year.

Yes, and it is the most common setup when the dryer sits against an exterior wall. The duct passes through the 2×4 or 2×6 cavity in a rigid section, the hole is sized to fit the pipe, and the gap around it is sealed so warm, damp air cannot leak into the wall. Keep the flexible connector on the room side. If the wall is poorly insulated, the duct may need insulation too, which is covered below.

Straight outside, through a hood with a damper that opens when the dryer runs and closes when it stops. That keeps cold air, rain and small animals out. Skip the mesh cover some people add to keep insects away. Lint builds up on it quickly and can nearly close the opening within a few months.

Quebec winters add a few practical points. Place the hood above the snow line, and keep it away from windows, doors and fresh air intakes so damp exhaust does not drift back inside. Check the hood after storms, since Montreal’s fire department specifically recommends making sure the outlet is free of lint, snow and ice.

For standard vented dryers, no. Discharging into the house is what the National Building Code rules out, because the lint and moisture end up inside your walls and air. The exception is a condensing or heat pump dryer, which is ventless by design and drains its water instead.

Insulation is not something I could confirm as a code requirement, but it is good practice wherever the duct crosses an unheated space such as a garage, crawlspace or cold exterior wall. Warm, humid air cools quickly against cold metal, and the condensation that forms turns lint into damp clumps that stick to the pipe. A preformed insulating sleeve solves it in minutes. If you are already noticing damp spots or foggy windows near the laundry room, measuring your home’s humidity can show whether the dryer is part of the problem.

You can, as long as you follow the manual, use rigid metal and stay within the length allowance. It is worth calling a professional when the route is long, passes through a finished wall or roof, or includes several bends. Homeowners sometimes forget to check with their insurer either, since a non compliant installation could complicate a claim after a fire.

Once a year is a sound baseline for most households. Large families, long runs and lots of bends call for shorter intervals. A vent can be installed perfectly and still fill with lint over time, so cleaning matters as much as the original layout.

Longer drying times, a dryer that feels unusually hot, a burning smell or lint collecting around the outside hood all point to a blocked vent. If you are seeing those signs, our guide on why a dryer stops drying properly walks through the usual causes. A dryer vent cleaning covers the whole run from the back of the machine to the exterior hood, which a store bought brush rarely reaches.