The genuinely transformative part of a smart lock is not that you can open it with a phone. It is that you can give someone access without giving them a key, know when they used it, and take it away afterwards without changing a lock.
Physical keys have none of those properties. A key you lend is a key that can be copied, and you have no idea when it was used or whether it came back alone. Managing this well is mostly about a few habits.
One credential per person, always
The foundational rule, and the one most households break.
A single shared code that everyone knows tells you nothing. When it appears in your log you learn only that somebody came in. You cannot revoke it for one person, and when you eventually change it you have to tell everybody.
Individual credentials give you three things: an audit trail worth reading, selective revocation, and per-person automation — the heating coming on when a particular family member arrives, or a notification only when the cleaner does.
It costs nothing. Most locks support dozens of codes, and naming them properly at setup is five minutes of work that pays back permanently.
Temporary access, done properly
Different visitors need different arrangements, and matching them is the skill.
A tradesperson coming once. A code valid for a specific day, ideally within a time window, that expires by itself. Expiry is far better than intending to delete it later, because nobody deletes it later.
A cleaner every Thursday. A recurring code valid on Thursdays between set hours. Outside that window it does not work, which protects both of you — and that is worth saying out loud, because a clear access arrangement removes suspicion in both directions.
A neighbour holding emergency access. A permanent code they know exists and rarely use, with a notification when it is used. Better than a key under a plant pot by a wide margin.
Guests staying. A code for the duration of the stay, deleted on departure.
A dog walker or carer. A recurring code plus a notification, so you know the visit happened — which for a carer visiting a relative is genuinely valuable reassurance.
A delivery driver. We would not, generally. One-time codes for deliveries exist and the risk is asymmetric. A secure parcel box is the better answer.
Choosing codes that are not guessable
Access codes are usually four to eight digits, which is a small space, so how they are chosen matters.
Avoid years, especially recent ones and birth years, which are the first thing anyone tries. Avoid your house number, repeated digits, sequences, and anything written on a document in your recycling.
Prefer codes with more digits where the lock allows, since each extra digit multiplies the search space, and digits spread across the keypad to reduce wear clustering.
Two mechanical concerns. Wear patterns on a physical keypad reveal which digits are in use, so a scrambling display, an occasional change, or spreading digits across the pad all help. And overlooking — a keypad visible from a pavement or a neighbouring window is watched more easily than people think, so shield it with your hand out of habit.
Also check the lock's behaviour on repeated wrong attempts. A lock that locks out after several failures resists brute forcing; one that accepts unlimited attempts does not.
Reading your own log
An access log is only useful if someone looks at it, and nobody looks at it routinely. So automate the looking.
Alerts worth building: any use of a code that should not be active; access outside expected hours, such as the cleaner's code at 11pm; the emergency neighbour code being used at all; repeated failed attempts; and a door unlocked for longer than usual.
Then use the absence of events too. A carer's visit that did not happen, or a child who has not arrived home by the usual time, are more useful signals than most of the alerts above, and they only work if you know the normal pattern first.
Give it a few weeks before setting thresholds. Real households are less regular than they assume, and rules set on day one produce noise.
Access to the automation system itself
The lock is not the only credential in play. Whoever can control your hub can open your door, and this is the part most households never consider.
Separate accounts for household members, with permissions matched to what each person actually needs. Everyone sharing one login gives everyone full administrative control.
Consider carefully what a guest user can do. Someone who should be able to turn on lights does not need to unlock doors.
Voice assistants and door locks deserve thought. A voice command that unlocks a door can be issued by anyone within earshot, including through a letterbox or an open window. Requiring a spoken PIN helps; not exposing unlock to voice at all is safer, and locking by voice while requiring something else to unlock is a sensible asymmetry.
Two-factor authentication on any account that can open your house. This is not paranoia — a reused password from a breached website is a realistic route in.
Remove people properly when they leave. An ex-flatmate's account, a former partner's app access, a departed cleaner's code. This is the commonest real-world failure and it is entirely about process rather than technology.
Physical keys still matter
Digital credentials are better in almost every way except one: they need power.
So keep a physical key arrangement, and keep it sensible. A key with someone you trust, not under a mat, a stone or a plant pot — the hiding places people use are the places people look. A key safe is acceptable if it is a decent one properly fitted, and note that cheap ones are trivially defeated. And know who has keys, which in a house that has changed hands or had lodgers is frequently unknowable, and is a good reason to change a cylinder when you move in.
A set-up we would recommend
- One named credential per person, no shared codes.
- Expiring codes for one-off visitors, set at creation rather than deleted later.
- Time-windowed recurring codes for regular visitors.
- One permanent emergency code with a trusted neighbour, with notification.
- Alerts on unexpected use, failed attempts and doors left unlocked.
- Separate hub accounts with appropriate permissions, and two-factor on all of them.
- Voice can lock, not unlock.
- A quarterly review of every code and account, deleting anything you cannot account for.
Item eight takes ten minutes and is the one that actually keeps the system trustworthy. Access lists accumulate silently, and the code you cannot explain is the one to remove.