Lock Maintenance Before a New England Winter

Every winter, the same calls start once the first hard freeze arrives: a front door key that will not go in, a car door lock packed with ice, a mailbox lock that has seized after a week of sleet. HMS Locksmith, based in Allston and working across Greater Boston, sees most of these problems start in the fall, when a lock that was a little stiff gets ignored until it is frozen solid. A bit of winter lock maintenance in October and November prevents most of them.

Here is a straightforward checklist for homes, cars and the small locks people forget, plus what to do if a lock freezes anyway.

Why cold weather is hard on locks

Locks are full of small moving parts with tight clearances. Water gets in through the keyway, freezes and expands, and the pins or wafers stop moving. Dirt and old grease thicken in the cold and make the problem worse. Outdoor locks, the ones on mailboxes, gates and sheds, have the hardest time, and our own mailbox page notes that mailbox locks exposed to the weather are especially prone to jamming.

Doors also move a little with the seasons, so a deadbolt that lines up in September can start to drag in January.

The National Weather Service winter safety guide is worth reading before the first storm, because the same cold snaps that freeze pipes also stiffen lock cylinders and car door locks.

A fall checklist for home locks

Walk around the house on a dry day and check each exterior door:

• Turn every key and thumb turn. Note any lock that feels gritty, stiff or needs a jiggle.
• Throw each deadbolt with the door closed. If you have to push or lift the door to get the bolt to engage, the strike needs adjusting before it gets worse.
• Lubricate with a product made for locks. A light spray into the keyway, then work the key in and out a few times and wipe off any excess.
• Check weatherstripping and door sweeps. Gaps let in water, which ends up in the lock.
• Look at the keys. A worn key is harder on the lock and more likely to break off in the cold. Get a fresh copy cut from a good key while you still have one.

If a lock is worn rather than just dry, it is better to deal with it now. Our lock change and repair service can repair the existing lock, replace just the cylinder, or install a new lock if that makes more sense.

Car locks and fobs

Most drivers use the fob, but the mechanical key slot on the door is your backup when the fob battery dies on a cold morning. Keep it working:

• Spray a lubricant made for car door locks into the key slot before the freeze.
• Replace the fob battery in the fall instead of waiting for it to fail in January.
• Keep a small can of lock de-icer at home or at work, not inside the car, where you cannot reach it.

The small outdoor locks

Mailboxes, gates, sheds and storage units all have locks that sit in the weather. Give each one the same treatment as your front door. For padlocks that live outside, a strip of tape over the keyway and a plastic bag over the lock helps keep water out.

When a lock freezes anyway

Even with good prep, a lock can ice up after freezing rain. What helps:

• Use de-icer. A de-icer that contains lubricant, sprayed on the key or into the lock, is one of the most effective fixes.
• Do not pour hot water on it. It refreezes quickly, and on a car the sudden temperature change can cause damage.
• Do not force the key. Forcing a key into or through a frozen lock is how keys snap off.

If a key does break off, stop. We can usually extract it and either repair the lock or cut a new key, at home or at the car.

A note on timing

Other trades build their year around the seasons in the same way, with a cooling check in spring and a furnace check in fall. Fall is the right time for locks, too, before the first deep freeze rather than after it.

Serving Newton, Boston and nearby towns

We work throughout Boston, from Roslindale and West Roxbury to Charlestown and South Boston, and in surrounding towns including Newton, Wellesley and Needham. For service in Newton, see our Newton locksmith page.

Frequently asked questions

What should I use to lubricate my door locks before winter?

Use a lubricant sold for locks, applied lightly into the keyway, then work the key a few times and wipe off the excess. Do it in the fall, before the first freeze.

Is it safe to pour hot water on a frozen car lock?

No. Hot water refreezes quickly, and the sudden temperature change can damage the car. A lock de-icer is the better choice.

My key broke off in a frozen lock. What now?

Stop turning it and do not try to dig it out with a pin or knife. A locksmith can usually extract a broken key and repair the lock or cut a new key on site.

Trusted Local Network

We like to point readers toward businesses that do careful work in their own trades and markets. Two worth a look:

• A public adjusting firm in Oregon and Washington explains how it documents vandalism and theft insurance claims with photos, serial numbers and written statements when receipts are missing.
• A family-owned transmission and auto repair shop in DeSoto, Texas, offers check engine light diagnostics that read the trouble codes stored in a car’s computer before any parts are replaced.

Your Greater Boston Winter Lock Care Specialists

If a lock is already stiff, sticking or hard to turn, reach our team through the contact page to have it looked at before the cold sets in. Call (617) 249-4949 to talk through repair, rekeying or replacement.

HMS Locksmith is based in Allston and serves Boston and nearby communities across Suffolk, Middlesex, Norfolk and Essex counties, including Cambridge, Somerville, Brookline, Newton and Quincy. Learn more about our lock change and repair service, or see what neighbors say in the HMS Locksmith Google reviews before you book.