Road salt and your garage door: a North Shore winter guide

Every January we take a call that starts "I think the salt air off the lake has got to my springs." It hasn't. Lake Michigan is fresh water, and there is no salt air on Sheridan Road. What has got to your springs is road salt, carried home on your own tyres — and that is the bigger problem, not the smaller one.

Killing the myth first

The Great Lakes hold roughly 21% of the world's surface fresh water and 84% of North America's, according to the EPA's Great Lakes facts and figures. No salt in it. No salt spray coming off it. No marine atmosphere anywhere in Evanston, Wilmette or Kenilworth.

So when you read a garage door company writing about "coastal corrosion" or "salt air from the lake" on the North Shore, you are reading a template written for somewhere with a tide. It is a tell. The people who wrote it have never opened a garage on a February morning in south Evanston.

The real corrosion story here is more specific, better documented, and considerably worse for your door.

What actually goes down on the road

The City of Evanston publishes what it applies. In a recent winter, it reported spreading 3,377 tons of pre-wet granular salt and 52,616 gallons of salt brine across 190 miles of road, at a standard rate of 200 pounds per lane-mile. That figure represents a genuine 40% reduction in bulk salt over four seasons — the City has been working the number down deliberately, and the City's own reporting is where to check the current one.

Down 40% and still thousands of tons. It has to go somewhere.

Where it goes is your tyres, your wheel arches and the soles of your boots. You drive down Dodge, turn into the alley, pull in, and a few pounds of salt-laden slush drops off the underside of the car onto the slab. In an attached, heated garage it dries and gets swept out eventually. In an unheated detached garage on an alley — which is what most of this town has — it does not dry, it does not drain, and it does not go anywhere until April. It just sits there evaporating slowly into the air around your springs.

How cold it gets, and for how long

Numbers matter here, because the duration is the point. From NOAA's 1991–2020 climate normals for the official Chicago station:

• 121 days a year with a low at or below freezing
• 6.5 days a year at or below 0°F
• January averages a high of 31.6°F against a low of 18.8°F — the daily swing straddles the freezing point through most of midwinter
• Annual snowfall normal of 38.4 inches

That third line is the one that does damage. A door and its hardware are not held at a steady cold. They are taken above and below freezing most days for four months, with a salty damp film sitting on the steel throughout. Wet, frozen, wet, frozen.

Then there are the outliers. On 30–31 January 2019, the polar vortex took Chicago to −23°F and the city spent 52 consecutive hours below zero. In the week that followed we replaced springs on doors that had been perfectly serviceable in December. That kind of event does not create a fault. It finds one.

What salt actually does to steel

This part is worth understanding properly, because most explanations of it are wrong in a way that leads homeowners to the wrong response.

Salt does not make a spring snap. Salt makes a spring fail early.

A torsion spring is a fatigue component. Every time the door goes up and comes down, the wire is twisted and released, and each cycle uses up a fraction of the spring's life. It is engineered on the assumption that the wire's surface is smooth, because a fatigue crack has to start somewhere, and where it starts is a stress concentration — a notch, a pit, a flaw.

Corrosion manufactures those. Every pit in the surface of the wire is a tiny notch, and every notch is a place a crack can begin. So a spring rated at 10,000 cycles in clean, dry conditions does not give you 10,000 cycles in a salt-laden unheated garage. It gives you fewer, and nobody can tell you exactly how many fewer, because it depends on how wet your slab is and how much slush your car carries.

What that means practically: rust on a spring is not cosmetic. Orange bloom along the coils of a spring in a detached garage means it is living in the wrong environment and it will not make its rated life. That is worth knowing in October, when spring replacement is a scheduled job, rather than in January, when it is not.

Part by part: what salt reaches first

In rough order of how much it costs you:

• Torsion springs. Above the opening, on the shaft. They collect airborne moisture and hold it in the gaps between coils. Rust on the inner faces of the coils is invisible from below until the spring is unwound.
• Extension springs. On older single-car garages these run along the horizontal tracks. Same corrosion problem, plus they sit low enough to catch spray off the vehicle. If yours do not have safety containment cables through them, that is a separate and more urgent conversation.
• Lift cables. These rust from the bottom up, because the bottom end sits at the bottom bracket, an inch above a wet slab. By the time you can see fraying at the drum, the lower run has usually been going for a while. Cable replacement is cheap. A snapped cable at head height is not.
• Cable drums. Aluminium drums pit; the cable then runs over a rough groove and abrades itself faster.
• Roller stems and bearings. Unsealed steel rollers on old doors have an open bearing race. Salt-laden grit gets into it, the bearing seizes, and the roller drags along the track instead of turning. That is where most winter noise complaints actually come from — and a dragging roller wears its stem until it eventually leaves the track.
• Hinges. The hinge barrel and pin at each section joint. Seized hinges make the door flex where it should pivot, which cracks the steel skin at the corners.
• Bottom brackets. The most heavily loaded part on the door and the closest one to the floor. Both at once. A pitted, flaking bottom bracket carries the full lift cable tension, and there is no warning noise before one lets go.
• Bottom seal. Salt and repeated freezing harden the vinyl or rubber, it cracks, it stops shedding water, and then it holds water against the slab instead — which is what welds the door down overnight.
• Track. The most visible and the least urgent. Surface rust on track is normal. Pitting deep enough to catch a roller is not.

The routine that prevents most of this

One service, in autumn, before the first hard freeze. October is right; November is acceptable; December is late.

When the door is frozen to the slab

This is the single most expensive five minutes in an Evanston winter, and it happens to hundreds of doors in the same week.

Water pools at the threshold during an afternoon thaw. Overnight it freezes, and the bottom seal is now bonded to the concrete along its whole length. In the morning you press the button. The opener applies several hundred pounds of pull to a door that is physically stuck, and one of four things gives: the drive gear, the trolley, the top section where the opener arm attaches, or the cables — which go slack, jump the drums, and put the door off track.

What to do instead:

1. Try the button once, briefly. If the door does not start moving, stop. Do not hold it in, and do not try again "harder."
2. Pull the emergency release — but only if you can reach it without standing under the door.
3. Break the bond at the seal. Work along the joint between the seal and the slab with a plastic scraper or a flat piece of timber. Warm water along the seal works too, provided you then squeegee it away rather than leaving it to refreeze.
4. Lift by hand once it is free, then run the opener normally and check the door closes and seals properly.

What you must not do is turn the opener's force setting up. That setting exists so the door reverses when it meets an obstruction. Turning it up to punch through ice disables the safety on every subsequent cycle, including the ones with a person underneath. If the door needs more force this winter than last winter, something is wrong with the door — not with the setting.

If it has already gone bang and the door is hanging crooked, stop and call for emergency service rather than working it loose. A door with a jumped cable is carrying weight through parts not designed for it.

Why the door matters more here than it does in the suburbs

Evanston's on-street parking rules in winter are strict, and they are the reason a working garage door stops being a convenience and becomes logistics. From the City's snow parking regulations:

• Two inches triggers the snow route ban: no parking on designated snow routes between 11 p.m. and 6 a.m. Emergency sirens sound at 8:15 p.m. as the warning.
• Four inches or more triggers a snow emergency: alternate-side parking, with no parking 8 a.m. to 6 p.m. on even-numbered sides on even dates and odd sides on odd dates. Sirens sound at 7:15 a.m. and 12:15 p.m.
• Residents must clear sidewalks to 36 inches wide after any accumulation, and may not push snow into streets, alleys or sidewalks.

Confirm the current rules with the City, because they get revised. But note that last one, because it explains the ice at your threshold: nobody on your block is permitted to shovel snow into the alley, so what accumulates on the apron in front of your garage stays there, melts in the afternoon sun, runs to the low spot and freezes overnight. That is the mechanism behind most of the frozen-door calls we take, and it is described in more detail in our piece on what an alley does to a garage door.

The practical version: on the night the sirens go at 8:15, the car needs to be in the garage, and the door needs to work. That is the whole argument for booking the autumn service.

If your springs already look rusty, or a roller has started grinding, call (224) 505-2236 before the first freeze. Both are ordinary jobs in October and awkward ones in January, and roller replacement in particular is the cheapest hour you will spend on the door all year.

Frequently asked questions