You sit down on the couch in January and feel a thread of cold air along your neck. You walk past the front door and the hallway is several degrees colder than the kitchen. You put your hand near a bedroom window and feel the chill coming through.
Drafts are one of the most common complaints in GTA homes, and they're more than an annoyance. A draft means air is moving through a gap that shouldn't be there. That gap is letting heat out, letting cold and moisture in, and making your furnace work harder than it should.
This guide explains where drafts come from, how to find the source, what each type of draft tells you about the condition of your windows and doors, which fixes are worth trying yourself, and when replacement is the smarter long-term decision.
Why Drafts Matter More Than They Seem
Natural Resources Canada estimates that air leakage can account for 25 to 40 percent of the heat lost from an older home. Windows and doors are the most common leak points because they're the places where the building envelope is interrupted by moving parts.
A draft affects more than the heating bill:
- Comfort. Moving cold air feels colder than still air at the same temperature. A room with drafts never feels fully warm, even when the thermostat says it should.
- Moisture. Air leaks carry humidity. In winter, warm indoor air leaking out through a gap can condense inside the wall or frame, leading to rot, mould, and staining.
- Furnace wear. A furnace that runs longer to compensate for leaks wears out sooner.
- Noise and dust. The same gaps that let air in let street noise and dust in too.
How to Find Where the Draft Is Coming From
Before you can fix a draft, you need to locate it. A few simple methods work well on a cold, windy day.
The hand test
Slowly move the back of your hand around the edges of the window or door frame, along the sash joints, and near the lock. The back of your hand is more sensitive to temperature change than your palm.
The candle or incense test
Hold a lit candle or incense stick near the frame. Watch the flame or smoke. If it flickers or bends sideways, air is moving through a gap at that spot. Keep flames away from curtains.
The flashlight test
At night, have someone shine a flashlight around the frame from outside while you watch from inside. Light coming through means air can too.
The paper test
Close a window or door on a sheet of paper. If you can pull the paper out easily, the seal isn't compressing properly at that point.
A professional energy audit
A certified energy advisor can perform a blower door test that depressurizes the house and pinpoints every leak with a thermal camera. This is the most thorough method and is often part of qualifying for energy rebate programs.
What Different Drafts Tell You
Where the draft comes from says a lot about what's wrong.
Draft between the sash and the frame
If cold air comes through the gap where the moving part of the window (the sash) meets the frame, the weatherstripping is likely worn, compressed, or missing. On older windows, the sash itself may have warped so it no longer sits flush. This is the most common type of window draft.
Draft around the outside of the frame
If air comes from where the frame meets the wall, trim, or sill, the problem is in the installation. The gap between the window frame and the rough opening was never properly insulated or sealed, or the sealant has cracked and pulled away over time. This is common in older homes and in windows that were installed quickly.
Draft through the glass area
If you feel cold radiating from the glass itself rather than moving air, that's not technically a draft. It's conduction through poorly insulating glass. Single-pane windows and double-pane units with failed seals (often visible as fog between the panes) lose heat this way. The air near the glass cools, sinks, and creates a convection current that feels like a draft. The fix is better glass, not weatherstripping.
Draft at the bottom of a door
Cold air at floor level along an exterior door usually means the door sweep or threshold seal is worn, missing, or no longer meeting the door. This is one of the easiest drafts to fix.
Draft along the sides or top of a door
Air leaking around the sides or top of a door points to worn weatherstripping in the frame, a door that has sagged on its hinges, or a frame that has shifted. If the door has to be lifted or pushed hard to latch, alignment is the issue.
Draft through a patio door
Sliding patio doors are prone to drafts along the meeting rail (where the two panels overlap) and at the bottom track. Worn rollers let the panel drop, breaking the seal. Learn more in our guide to signs you need patio door replacement.
Draft from a window that won't lock tightly
If the lock doesn't pull the sash firmly against the frame, the weatherstripping can't compress and seal. This can be a worn lock, a misaligned keeper, or a sash that has shifted.
Quick Fixes That Can Help
Some drafts can be reduced with inexpensive repairs. These are worth trying when the window or door is otherwise in good condition.
- Replace weatherstripping. Foam, rubber, or V-strip weatherstripping is sold at hardware stores and installs in minutes. Match the type to your window or door.
- Re-caulk the exterior. Remove cracked sealant where the frame meets the siding or brick and apply a fresh bead of exterior-grade caulk.
- Install or replace a door sweep. A new sweep at the bottom of an entry door stops floor-level drafts.
- Adjust the threshold. Many thresholds have adjustment screws that raise them to meet the door bottom.
- Tighten or adjust hinges. A sagging door can often be fixed by tightening or replacing hinge screws with longer ones that bite into the framing.
- Use removable window film. Plastic film shrink-fit over the interior of a leaky window creates an air barrier for the winter. It's a stopgap, not a solution.
- Add draft stoppers. Fabric tubes along the bottom of doors block floor-level air movement.
These fixes address the symptom. If the window or door is old, warped, or poorly installed, drafts tend to return.
When Repairs Aren't Enough
Replacement becomes the better choice when:
- The draft comes from around the frame. Fixing an installation gap properly means removing the trim, insulating the gap, and resealing, which is most of the work of a replacement anyway.
- The glass has failed. Fog or moisture between panes means the insulating seal is broken. The unit can't be repaired, and the window will keep losing heat.
- The frame is rotted, warped, or cracked. Wood frames that have softened or vinyl frames that have warped won't hold a seal no matter how much weatherstripping you add.
- The window is single-pane. Even a perfectly sealed single-pane window conducts far more heat than a modern insulated unit.
- Multiple windows or doors have the same problem. If drafts are everywhere, the whole set has reached the end of its life.
- The door is hollow or uninsulated. Older entry doors with little insulation conduct heat through the slab itself. See our guide on how to tell if your front door is costing you comfort and energy.
Our article on drafty windows in Toronto goes deeper on the window side of this decision.
What Replacement Should Deliver
A proper replacement does more than put a new window or door in the old hole. It should:
- Fit the opening precisely, with each unit measured individually
- Insulate the gap between frame and wall with low-expansion foam
- Seal inside and out with quality sealant
- Use compression-seal styles (casement, awning) where tight sealing matters most
- Include insulated glass with Low-E coating and gas fill, certified for Canada's climate
- For doors, use an insulated steel or fibreglass slab with a multi-point lock that pulls the door tight against the weatherstripping
Installation quality is what separates a replacement that stays draft-free for decades from one that leaks again in a few years. Our guide to what to expect during your window installation explains the process.
Drafts and Energy Rebates
Because air leakage is such a large share of home energy loss, window and door replacement often qualifies for energy efficiency incentives. Programs change, so confirm current eligibility, but ENERGY STAR certified products installed by a qualified contractor have typically been required. Our article on Ontario window rebates and deadlines covers what to look for.
Final Thoughts
A draft is information. It tells you exactly where your home is losing heat and where moisture can get in. Some drafts are quick fixes: new weatherstripping, fresh caulk, a door sweep. Others point to failed glass, rotted frames, or poor installation, and those need replacement.
Find the source first, then decide. If the window or door is otherwise sound, repair it. If the problem is in the glass, the frame, or the installation, replacement will solve the draft for good and improve comfort and energy performance across the board.
LAB Windows & Doors installs draft-free windows and doors across Toronto and the GTA. If you'd like a straightforward assessment of where your home is leaking and what to do about it, book a free in-home consultation.