Alarms in Project Zomboid

Some buildings are flagged as alarmed when the world is generated. Nothing on the outside shows it. The first time the alarm is tripped a siren plays, a very large world sound is sent out, and zombies from the surrounding streets start walking to the building. The flag then clears, so each building's alarm fires once and does not re-arm.

A Build 42.20 guide that reads the game data says only buildings with more than two rooms can be alarmed (one source). Houses, shops and offices all qualify. How many are alarmed is set by House Alarms Frequency in the sandbox settings.

The older wiki page lists zombie triggering as off by default. Build 42 sources list it as on for Apocalypse.

Per the Build 42.20 data-based guide (one source), these actions trip an alarmed building:

• Smashing one of its windows.
• Opening one of its windows.
• Walking into a room of the building.

Opening a door does not trip it by itself, but stepping through does. An opening that was already broken can still set it off.

Alarms do not stop when the power goes out. On default settings an alarm can stay live for up to 30 days after the grid fails, and you cannot tell which ones are dead. Zombies walk to the building, not to you, and many stop short once the siren ends. They only switch to you if they see or hear you on the way.

In unmodded Build 42 you cannot check a building for an alarm and you cannot disarm one. Guides written for 42.20 agree there is no detector, no panel and no option to silence a siren, and Electrical skill does nothing for house alarms. The Burglar occupation hotwires cars without the skill check, but it has no vanilla alarm ability either. See traits and occupations.

The Electrical and Burglar requirements you may have read about come from Workshop mods. One popular alarm mod lets a Burglar, or a character with Electrical 3, look through a window to detect an alarm, and disarm it at Electrical 5 with a screwdriver or credit card and scissors.

Opinion Without mods, treat every closed building with more than two rooms as alarmed for the first month. Clear the street first, pick the window nearest your escape route, and keep your bag light enough to run.

A share of parked vehicles carry an alarm, set by Vehicle Alarms Frequency (Rare on Apocalypse, Never on Six Months Later). The older wiki text for the setting describes the alarm as going off when a door is opened, and Build 42 guides add that a failed hotwire attempt can set it off.

Once it starts, the horn and lights keep going. A player on the Steam forum reports that disconnecting the battery was the only thing that stopped it (one source). No source gives a tile radius or a fixed duration for car alarms in Build 42.

Opinion To lower the odds of tripping one:

• Look for the key first: on nearby zombies, on the ground, in the glove box and in the closest house.
• Clear the lot before you touch a car you have no key for.
• Do not break into cars beside a crowd or beside your base.

The vehicles guide covers keys and hotwiring, and mechanics covers removing parts.

Alarm clocks and digital watches have a settable alarm. Right-click the item to set the time and switch the alarm on or off. Some watches are found with the alarm already set and will beep on your wrist or in your bag until you turn it off, so check every digital watch you pick up. A ringing alarm clock has a Stop Alarm option. The alarm also wakes you. See sleep.

These figures have not been re-confirmed for 42.22. Opinion At these ranges a clock is a room-sized lure, not a street-sized one. Set it a few minutes ahead, drop it at one end of a building and enter from the other, or leave one outside a window to pull the zombies that are pressed against it. An unchecked watch in your bag can give you away while you sneak. See stealth.

Zombies walk to the last loud sound they heard and stop there unless they see a survivor. The Follow Sound Distance setting (100 by default) limits how far they keep walking.

• House alarm. Trip it on purpose, leave, and loot the far side of town while the streets drain toward the siren. It only works once per building.
• Car horn. A few honks, then drive off. Players report a reach of a few hundred tiles, with no exact figure.
• Emergency siren. Police cars, ambulances and fire trucks keep calling zombies while the battery lasts. Vehicle Sirens Attract Zombies is on by default.
• Gunshots. About 60 to 200 tiles depending on the gun. See firearms.
• Loud TV or radio. Short range. See radio.

Opinion Pull the horde away from where you want to be, not toward a spot between you and home. Never use a 600 tile alarm within a few blocks of your base, and agree on this with other players in multiplayer. The zombies page explains hearing settings.

Opinion You cannot shut a house siren off, so do not look for a switch. Every zombie in range is now walking to the building you are standing in.

1. Decide in two seconds: leave now, or grab the one item you came for if it is within arm's reach. Then leave.
2. Exit on the side away from the densest street. Walk or jog.
3. Break line of sight with a fence or tree line and get at least a block away. Zombies that have not seen you will pass you and head to the house.
4. Do not shoot. A gunshot adds a second sound at your position. See combat.
5. Wait it out. Come back hours later and thin the crowd from the edges.

For a car alarm the choice is simpler: if you have the key or it hotwired, drive away and deal with the battery somewhere quiet. If not, walk away from the car.