The Basics of Your Home’s Locks
A little know-how about your locks goes a long way. Here’s how a door lock works, what’s normal, and what to try before you pick up the phone.
Most of us never think about our locks until one gives us trouble. A little time spent learning the parts and the warning signs can spare you a stuck door on a cold morning, and it makes it much easier to explain the trouble when you do call.
The Parts of a Door Lock
Every lock on an outside door is built from the same handful of parts:
- Cylinder: the part your key goes into. Small pins inside line up only for the right key.
- Latch: the slanted bolt that pops out and holds the door shut when you close it. The knob or lever pulls it back.
- Deadbolt: a square-ended bolt you throw with a key or a thumb turn. It doesn’t spring back, so it can’t be pushed in from outside.
- Throw: how far the deadbolt reaches out of the door. A full throw sits deep in the frame.
- Strike plate: the metal plate on the frame that the latch and bolt slide into.
- Hinges: they hold the door square in its frame. When their screws loosen, the door sags and the lock stops lining up.
Many older Columbus houses still have mortise locks. In those, the latch, the bolt and the works sit together in a box set into a pocket in the edge of the door, behind a flat plate. They’re built to last, but their springs and parts do wear.
Latch or Deadbolt
A knob or lever latch keeps the door closed. A deadbolt keeps it locked. The latch is slanted so the door can swing shut and catch on its own, which also makes it the easier of the two to force. A deadbolt is square and has to be turned into place, so it holds even when someone pushes on the door.
That’s why most outside doors have both. If a door only has a locking knob, a deadbolt above it is a sensible addition.
What’s Normal and What Isn’t
Locks aren’t perfectly snug, and some give is part of how they work. Here’s how to tell ordinary wear from trouble.
| What you notice | Usually normal? | What it means |
|---|---|---|
| A little play in the knob or lever | Yes | Some slack is built in so the latch can catch the strike without binding. |
| The door latches a bit harder in winter than in summer | Often, in wood doors | Wood swells and shrinks with the weather. If it gets worse each year, the strike or hinges may need adjusting. |
| You have to push, pull or lift the door to throw the deadbolt | No | The bolt and the strike no longer line up. The door may have sagged or the frame shifted. |
| The key goes in stiff or has to be wiggled every time | No | A worn key, worn pins or dirt in the cylinder. |
| The key turns, but nothing happens | No | Something inside the lock has worn or broken. |
| The latch doesn’t spring back out on its own | No | A weak spring, or grime packed around the latch. |
| The knob or lever feels loose on the door | No | Screws are backing out. Snug them up before the parts start to wear. |
What to Check Before You Call
A few easy checks can sometimes get a lock working again, or at least tell you what’s wrong:
- Lift or push the door gently while you turn the key. If the bolt slides easily then, the door has shifted and the lock itself is probably fine.
- Look at the strike plate and hinge screws. Tighten any that have worked loose.
- Check the edge of the strike for fresh scrape marks. They show where the bolt is rubbing.
- Try the spare key. If it works smoothly, the trouble is your everyday key, not the lock.
- Don’t force a key that won’t turn. A key that snaps off in the cylinder turns a small job into a bigger one.
If none of that helps, or the lock is getting worse, it’s time for a lock repair before it fails on you.
Good to Know When You Call
- Your address, and whether it’s a house, a duplex or an apartment
- Which door it is, and whether it has a knob, a lever, a deadbolt or a mortise lock
- What the lock is doing, and when it started
- Whether you have a working key, and how many keys are out there
- A photo of the lock and the edge of the door, if you can take one
Small Care That Keeps Locks Working
Locks last longer with a little attention. Keep hinge and strike screws snug, and keep the keyway clear of grit. Skip heavy household oil in a cylinder, since it gathers dust and gums up the pins over time; a locksmith usually cleans a lock and uses a dry lubricant instead. Once a year, before the cold sets in, it’s worth checking that every deadbolt still throws all the way without pushing on the door.
Cleaning and lubricating aging locks and adjusting strike plates and hinges is what our maintenance and inspections are for, if you’d rather have a locksmith look things over.
Tell us about the lock, the door or the car, and we’ll take it from there.