Do I need a burglar alarm, and should it be monitored?

What an alarm adds over locks and lighting, the honest difference between bells-only, app-notified and professionally monitored, and where the money goes.

Difficulty: beginner
Time: 40 min
Read: 5 min

Short answer

An alarm is a good third or fourth step, not a first one — locks, lighting and access come first. Bells-only makes noise and relies on someone caring; app-notified tells you but not anyone else; professionally monitored costs a monthly fee and produces a response. Choose by who you expect to react.

The useful question is not whether an alarm works but what it is supposed to cause to happen. A siren in an empty street at three in the morning causes very little. A phone notification while you are abroad causes anxiety unless someone locally can act. Deciding who the alarm is talking to settles nearly every other choice.

Where alarm detection goes, and who each system talks to

Step by step

Do the cheaper things first.A tested cylinder, a locked side gate, cut-back cover, motion lighting and windows actually locked. These prevent; an alarm reacts. Fitting an alarm to a house with an unlocked side gate is the wrong order.
Decide who is supposed to respond.You, a neighbour, a keyholder, or a monitoring centre. That single answer decides bells-only, app-notified or monitored, and it is the question most sales conversations skip.
Understand bells-only honestly.A siren and a flashing box. It shortens the time an intruder is willing to spend and it warns anyone in the house. It does not summon anybody, and neighbours very often ignore alarms because false alarms have trained them to.
Understand app-notified systems.Most modern DIY systems push a notification and a camera clip to your phone. Excellent for knowing, and for cancelling a false alarm quickly. Useless if you cannot get anyone to the house.
Understand professional monitoring.A monitoring centre receives the signal and follows an agreed procedure — usually calling you and your keyholders. A police response requires the system to be installed and maintained to the relevant standard and registered under the police policy, which a DIY system will not meet.
Plan the detection layout, not just the panel.Contacts on the doors you actually use, a movement detector covering the hall and stairs because everything passes through there, and detection on any vulnerable ground-floor room. Blanket coverage of every room is rarely worth it.
Set it up so it gets used.Part-set for nights so bedrooms are free while downstairs is armed, pet-tolerant detectors if you have a cat or dog, and entry times long enough for the slowest person in the house. An alarm that is annoying to set stops being set.
Compare the whole cost over five years.Kit, installation, monitoring fee, annual maintenance and the contract length. A cheap install with a long expensive contract frequently costs more than a better system bought outright.
Ask what happens when power or broadband fails.Battery backup in the panel and detectors, and a mobile signalling path if the broadband drops. A system that goes silent in a power cut is a system with an obvious blind spot.
Tell your insurer, and read the condition.A discount is common but the policy may then require the alarm to be set whenever the house is empty, and maintained. That condition is binding once accepted.

Tips

Registering with the police for a monitored system requires a professionally installed and maintained alarm to the current standard. If police response is the goal, say so at the quoting stage.
Repeated false alarms lose you both neighbour goodwill and, on monitored systems, police response. Setup quality matters more than sensor count.
Put a detector where an intruder must pass rather than where the valuables are. The hall and stairs cover almost every route through a house.

Common mistakes

Buying monitoring with nobody able to attend — The monitoring centre's job is to escalate to keyholders. With no local keyholder the response chain stops at a phone call to someone hundreds of miles away.
Signing a long contract for a cheap installation — The equipment is often the small part. A five-year contract at a monthly fee can cost several times an outright purchase, and cancelling early is usually expensive.

If it doesn't work

Household stopped setting the alarm

Cause: Entry time too short, pets triggering it, or an awkward keypad position — Fix: Lengthen entry and exit times, fit pet-tolerant detectors, move the keypad to the door people actually use, and set up part-setting for nights.

Alarm sounds when nobody is in and neighbours ignore it

Cause: History of false alarms — Fix: Fix the false alarm cause first, then tell the neighbours it has been fixed. Credibility is the working part of a bells-only system.

System stops signalling during a power cut

Cause: No battery backup or no mobile signalling path — Fix: Confirm the panel battery is healthy — they last a few years — and add a mobile signalling module if the system depends on broadband alone.

Alternatives

Standalone door and shed alarms: Battery units on the shed, garage and back door for a few pounds each. No monitoring, no contract, and noise exactly where nobody wants it.
A camera plus a keyholding neighbour: For many households the practical alternative: you get a clip, and someone nearby can look. Cheaper than monitoring and often more responsive.
A visible bell box with no system: Widely done and mildly useful, but a dummy box that is obviously dead or unbranded can advertise the opposite. See the guide on dummy alarms before deciding.

Questions people ask

Does an alarm actually deter anyone?

A visible, credible system deters opportunists, who are most burglars. It is one layer among several, and it works best combined with the things that make a house look occupied and hard to approach unseen.

Will the police attend my alarm?

Only for systems installed and maintained to the current standard by a company registered under the police alarm policy, with a unique reference number. A self-installed system does not qualify, and repeated false alarms can withdraw response from one that does.

Are DIY wireless systems any good?

Modern ones are capable and cheap, and for a self-monitoring household they are often the sensible choice. They will not give you police response, and battery management across a dozen devices becomes a real chore.