Rule one: light level zero is the spawn trigger
Hostile mobs spawn only where block light is 0 — so every spawnable surface (opaque block, top face) must sit within a light source’s reach. Use our torch spacing calculator to grid any room, and remember height: a torch 3 blocks up reaches 3 fewer floor tiles.
Non-light methods that work everywhere
Where torches ruin the look, use spawn-blocking surfaces instead: bottom slabs, carpet, moss carpets, glass and top-half slabs never host spawns. Big flat roofs — the most forgotten spawn surface — are best covered in slabs. Water works too: mobs cannot spawn in water, which is why ocean-adjacent bases stay quiet.
The perimeter play
For a whole base, light the perimeter wall line and every cave mouth within ~60 blocks — caves are where night mobs actually come from. On servers, some players carpet-bomb the local caves with torches during a mining session; the mob cap is shared, so clearing caves genuinely reduces surface spawns at night.
What does NOT work
Fences do not stop spawning — mobs spawn on the ground inside fenced areas fine. Glass floors do not need torches (mobs cannot spawn on glass at all). And difficulty Peaceful removes hostile mobs entirely but also removes most farming loops — light and slabs are the tools that keep the game intact.
