Winter-Proofing Commercial Doors in the GTA: Closers, Seals & Thresholds (2026)

Homes have their own winter door problems, which we cover in our winter door problems guide. Commercial doors are a different story. They are heavier, they are opened far more often, they usually have closers and panic hardware, and when they fail, the business pays for it in heating bills, lost customers and staff complaints.

The biggest single change in winter is the door closer. Closers are hydraulic, and the oil inside gets thicker as it gets colder. A closer adjusted on a warm day can become sluggish in January, so the door stops short and does not latch. Adjust it on a cold day instead and it can slam in spring. Wind makes it worse, pushing tall entrance doors open or shut. At the same time, weatherstripping stiffens and cracks, sweeps wear through on salted thresholds, and water from melting snow gets into floor pivots and locks and freezes overnight.

None of these problems appear all at once. They build up over weeks, and by February a business has a door that lets in a steady stream of cold air, a lock that freezes on cold mornings and a floor that is always wet. A single pre-winter visit in October or November catches most of it. This guide is the checklist we use.

A hydraulic closer has three main adjustments. Sweep speed controls how fast the door travels from fully open to a few inches from the frame. Latch speed controls the last few inches, and it is the one that makes sure the latch clicks into the strike. Back-check slows the door as it is pushed open, so wind or a hard push does not throw it into the wall. Many closers also have a delayed action setting, which holds the door open a little longer for people with carts or mobility aids.

When the oil thickens in the cold, sweep and latch speed both slow down. A door that closed in five or six seconds in September can take much longer in January and stop before it latches. The answer is not to crank the closer as tight as it goes, because that makes the door hard to open and slams it on warmer days. The right fix is to adjust the valves on a cold day to a sensible speed, check that the door still opens easily, and replace closers that have leaked fluid or are too small for the door. Some closers use fluid designed to stay more consistent across temperatures, which helps on exposed entrances.

Wind is the other half of the problem. Tall entrance doors facing open parking lots or wide streets catch gusts that can overpower a weak closer. Back-check, a properly sized closer and, where needed, an overhead stop protect the hinges, frame and glass. If your door has already been blown open hard, check the hinges and pivots too, because a single gust can bend them.

Rear steel doors used for deliveries and garbage take the worst of the weather and the least care. Snow is piled against them, salt sits on the threshold, and the bottom of the door rusts from the inside out. When the frame or hinges are weak, staff start forcing the door, which bends it further. We see many of these doors fail in February, when a business can least afford an unlocked back door overnight.

Before winter, check that each rear door closes and locks, that the bottom edge is not rusted through, and that the sweep and threshold keep water out. If the door is heavily rusted or bent, our steel door repair vs replacement guide helps decide what makes sense. Remember that many rear doors are also required exits: they must open easily from inside and must never be blocked by snow or stored stock.

Exit doors deserve special attention. A rear exit that freezes shut, or is blocked by a snowbank, is a fire safety problem, not just an inconvenience. Our fire door inspection guide covers what exit and fire doors need to pass, and it is worth combining that check with the winter visit.

Vestibules, when a building has them, help a lot, but only if both sets of doors close properly. If the inner and outer doors are both slow to close, the vestibule stops working and cold air runs straight through. We check both sets of doors in the same visit.

For a full view of what goes wrong with doors in our climate, read common door problems in Toronto's weather and common door problems in the GTA. If your business has sliding entrances or patio doors, see sliding door track repair. For steel back doors that have rusted at the bottom, our steel door repair vs replacement guide helps you decide. And if a door was damaged by a break-in over the holidays, our break-in repair team and emergency service are available around the clock.