What Attracts Zombies to Bases in Project Zomboid (Build 42.19)
Build 42.19 · World sounds, line of sight, scheduled events, and population migration — not a permanent “base heat map.”
Quick answer
A claimed base does not generate a permanent attraction score. Zombies respond to world sound events (gunfire, construction, generators, vehicles, alarms, helicopter), line of sight through open or undressed windows and outdoor movement, and population systems (redistribute / migration) that can refill empty cells over time. Local UI clicks, text chat, and light-switch audio alone are not the same as a world sound with a large radius.
1. Hearing — what actually counts as world noise
Zombies investigate sounds that enter the game’s world-sound system. Firearms have a tile-based noise radius, further scaled by the sandbox Firearm Noise Multiplier (default 1.0). Carpentry and other build actions create short-range world noise on the order of about 15–20 tiles (hammer work is quieter or louder depending on your character’s hammer sound modifier).
| Source (examples) | Approx. noise scale | Base implication |
|---|---|---|
|
JS-2000 / Double Barrel / sawn-off shotguns
|
About 200 tiles | Very large pull. Default firearm multiplier 1.0 — do not clear hordes at the front door. |
| Hunting / assault-style rifles (examples: Hunting Rifle ~170, M16-class ~150) | About 150–170 tiles | Still multi-block noise. Plan fall-back routes before shooting near home. |
| Common pistols / revolvers (examples: M9-class ~100, some short revolvers ~60) | About 60–120 tiles | Quieter than shotguns, not silent. Still enough to wake a quiet neighborhood. |
Building / hammering
|
About 15–20 tiles | Loud enough to pull street roamers. Clear or lure before fortifying in public view. |
Running generator
|
Continuous mechanical noise | Steady attractor after power shutoff. Place for coverage, not for stealth, and plan walls or distance from high-traffic roads. See the generator spawn guide. |
| Vehicles (engine, horn, alarms) | Engine-driven / event-based world noise | Do not idle or blare the horn next to a “quiet” safehouse. Disable car alarms before using a stolen car as base storage. |
| House / building alarms | Long, looping alarm noise | Breaking into alarmed buildings, or zombies breaking windows/doors when Zombie House Alarm Triggering is on, can dump a crowd on the block. Also check sandbox House Alarms Frequency. |
| Shout key / whisper (crouch + shout) | Deliberate player noise; whisper is much smaller | Crouch-shout whispers and attracts from a much smaller radius. Useful for controlled pulls, disastrous as accidental spam near home. |
Sandbox Hearing sets zombie hearing radius (Pinpoint / Normal / Poor / random mixes). Follow Sound Distance (default 100) is how far a zombie will keep walking toward the last sound it heard. Raising hearing or follow distance makes every base-side noise more dangerous; lowering them softens pulls without making you invisible.
What is not automatically “zombie chat”
-
Multiplayer text chat is channel-dependent.
Global
/alldoes not attract zombies; local channels such as/sayand/yellbehave differently. Do not treat “any teammate talking” as a guaranteed world sound. - Local UI audio ≠ world sound. Toggling a light plays a click for you; it does not create a large zombie world-sound event. Older rumors about a “light switch radius” do not apply as a current rule of thumb.
- Vanilla has no suppressor / silencer item. Low-noise shooting in vanilla means melee, careful pulls, or simply not firing. Workshop suppressors are mod content only — see the suppressor mod overview for Build 41/42 Workshop status, not as a vanilla recipe.
- Closed doors and windows do not magically erase every interior sound. They help with sight and pathing. Treat large firearm radii as neighborhood events regardless of curtains.
2. Vision — light, windows, and “being seen”
Lights mainly matter because they let you and zombies see through openings and outdoors at night — not because a lamp radiates a special attract-zombie aura. Sandbox Sight (Eagle / Normal / Poor) and Memory control how far zombies spot you and how long they remember a target after seeing or hearing you.
- Dress every street-facing window with curtains or sheets, and board or metal-sheet when you need impact resistance. Details: window boarding, sheets.
- Keep exterior doors closed when you are not moving loot. Open doors are free pathing and free sight lines.
- Indoor lights after dark make you readable through bare windows from the street. Curtains first, then lights — not the reverse.
- Outdoor activity at night is a sight problem even with a silent base interior. Fog and darkness change practical vision distance; see fog and zombie vision.
3. World events that dump zombies on “quiet” bases
Even careful survivors get company from systems that are not “your base was too loud yesterday.”
| Event / system | Sandbox option | What to do near a base |
|---|---|---|
| Helicopter / air activity | Helicopter Never / Once / Sometimes / Often (Apocalypse default is not Never) | If outdoors and visible, the chopper can track you and drag zombies with engine noise. Hide indoors out of sight, or leave the base area if already locked on. Full plan: helicopter event guide. |
| House alarms | House Alarms Frequency; Zombie House Alarm Triggering (true in Apocalypse) | Scout for alarm-capable buildings before smashing windows next to home. Zombies breaking in can re-trigger noise in the same neighborhood. |
| Car alarms / engines | Vehicle state (not a single “base” slider) | Park away from the main sleeping floor; disarm alarms; avoid horn spam as a “fun” signal. |
| Sirens, bombs, guns off-site | Same hearing / follow-sound rules | Distant fights still feed Follow Sound Distance. A quiet base can inherit a stream of walkers from someone else’s gunfight two blocks over. |
4. Population migration and “why did they show up later?”
Clearing the street once does not permanently empty a cell. Sandbox Redistribute Hours (default 12) is how many hours pass before zombies migrate into empty parts of the same cell; set to 0 to disable that migration. Combined with respawn-related options (separate from attraction), a silent base can still see gradual return traffic along roads and yards.
That is why fortification and clear sight-lines matter even when you play quietly: migration and events refill pressure that pure stealth does not cancel. For wall and safehouse workflow, use the wall building guide and safehouse guide.
Base defense checklist (map noise and sight to actions)
- Never fight with firearms on the doorstep unless the alternative is death. Pull to a prepared kill zone away from sleeping quarters.
- Barricade and dress windows on every street face before wiring generators or running night lights.
- Place generators for power coverage and accept their noise, or keep them off when you need a low profile. Do not put the only exit next to the generator.
- Build and haul during cleared windows — hammering is a short-range world sound, not free stealth carpentry.
- Disable vehicle and house alarms in your compound; treat alarm-heavy loot runs as temporary neighborhood black flags.
- On helicopter days, prioritize not being outdoors and visible over finishing a build project.
- Tune sandbox intentionally if you want a quieter career run: Hearing, Sight, Follow Sound Distance, Redistribute Hours, Helicopter, House Alarms Frequency, Firearm Noise Multiplier.
- In multiplayer, agree on shout key discipline and chat channels; do not assume voice-chat plugins or text spam equal vanilla world noise without testing your stack.
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