Night is when people notice it, for two reasons. The house is quiet, and in October the furnace starts cycling on and off through the night as outdoor temperatures drop. Metal and plastic grow and shrink with heat. A duct or pipe that is pinned against a joist, a stud or a strap slips a fraction of a millimetre at a time, and each slip is a tick that the wall carries like a speaker.
When does the noise happen? Narrow it down
Timing is the best clue. Note when it starts and stops for a night or two, and compare it with the furnace and the taps.
| What else you notice | Likely cause | How urgent | Who to call |
|---|---|---|---|
| Steady metallic ticking a minute or two after the furnace starts, slowing after it stops | Sheet-metal ducts expanding and contracting against framing or hangers | Not urgent | No one, or an HVAC technician to pad or re-hang a duct |
| Ticking along one wall after a shower, a bath or the dishwasher | Hot-water pipe expanding against a stud, strap or a tight hole | Not urgent | Plumber if it bothers you |
| One loud bang or thud right when a tap, toilet, washer or dishwasher shuts off | Water hammer: water stopping suddenly in the pipes | Fix soon: it shakes joints | Plumber |
| Random pops from the ceiling or roof on cold, clear nights, furnace off | Framing, nails and roof boards contracting as the house cools | Not urgent | No one |
| Scratching, scurrying or gnawing that moves, often at dusk and before dawn; droppings | Mice in the wall or ceiling | Book soon: fall is when they move in | Licensed exterminator |
| Dripping or trickling sound when the furnace runs | Furnace humidifier water line, or the condensate drain of a high-efficiency furnace or AC coil | Check soon | HVAC technician |
| Buzzing or crackling at a switch, outlet, fixture or the panel | Loose connection or arcing | Stop: urgent | Licensed electrician |
Why do my ducts tick when the heat comes on?
Warm air heats the thin sheet metal of the ducts in seconds, and the metal lengthens. Where a duct touches a joist, a metal hanger or the subfloor, it moves in tiny jumps instead of smoothly, and you hear a tick, often in a ceiling over a finished basement. When the blower stops, the duct cools and ticks again as it shrinks. RedFlagDeals posters describe it as clock-like ticking that stops shortly after the furnace turns off, and the fixes they report are the ones technicians use: a strip of foam or insulation between the duct and the hanger or joist, tightening a loose joint, or foil tape over seams. It is a comfort problem, not a safety one. A duct that bangs loudly once, like a drum, when the blower starts is called oil-canning; it can often be stiffened, but it is not dangerous either.
Why do pipes tick or bang inside the wall?
Ticking that follows hot water use is the pipe expanding, just like a duct. Copper and plastic pipe both do it, and the sound follows the pipe's route, so it often moves along a wall as the water heats. A single loud bang when a valve closes is different: that is water hammer. Water moving through the pipes stops suddenly at a fast-closing valve, such as the solenoid in a washing machine, dishwasher or fridge ice maker, and the pressure wave slams the pipe. Oatey, a plumbing manufacturer, recommends a water hammer arrestor installed as close as possible to the valve that causes it. Leaving it alone is not ideal, because repeated shocks stress joints and supply hoses.
How do I know if the noise in my walls is mice?
Mice do not tick on a schedule. Their sounds are light scratching, scurrying in short bursts and gnawing, they move from place to place, and they are loudest after dark and in the early morning, not in step with the furnace. Look for droppings about the size of a grain of rice along walls, in cupboards and behind appliances, chewed food packaging, or shredded insulation in the attic. Fall is when mice come inside for warmth. The Public Health Agency of Canada advises against sweeping or vacuuming droppings: wear gloves, wet them with a bleach solution, then wipe them up.
In Toronto and York Region homes, what is most common?
- Forced-air gas heat: Enbridge Gas supplies natural gas across Toronto, Vaughan, Richmond Hill, Markham, Newmarket and Aurora, and most houses here heat with a gas furnace and metal ducts, which is why duct ticking is the usual answer.
- Finished basements: ducts run through the basement ceiling and bulkheads, right under the drywall, so the sound carries into the room. Basement ceilings are where most ticking complaints come from.
- Older houses: 29% of the City of Toronto's homes were built in 1960 or earlier, and about 30% of Newmarket's before 1981 (Statistics Canada, 2021 Census). Older plumbing often has no modern hammer arrestors, and older houses usually have more gaps where mice get in.
- Newer subdivisions: about half of Vaughan's homes and 47% of Markham's date from 2001 or later. Long duct runs between floors in these houses make ticking easy to hear, and it is usually harmless.
What to tell the pro
- When it happens: when the furnace starts or stops, after hot water runs, when a tap or appliance shuts off, or at random.
- What it sounds like: tick, tap, bang, pop, scratch, drip or buzz. A 20-second phone recording helps a lot.
- Where: which wall or ceiling, which floor, and what is on the other side (bathroom, kitchen, duct bulkhead, attic).
- The house's age, whether the basement is finished, and the furnace's age.
- Anything else you have seen: droppings, a warm switch plate, flickering lights, water stains.
- Whether it is new this season or has happened every winter.
What does it cost to fix on Doyo?
It depends on the cause, so the agent first works out which trade you need. A furnace and duct check is Furnace Maintenance, $206.50; mice are Rodent Control, $531; an electrician's check of the panel is Panel Inspection, $246.40; and water hammer is Pipe Repair, priced by written quote. Every price is all-in with Doyo's fee included, and electricians, plumbers, gas technicians and exterminators on Doyo have their Ontario licence checked before they are offered the work.