Minecraft – Why doesn’t the technique stop spiders from spawning

minecraft-java-edition

I just starte playing minecraft a few days ago and there is one thing really annoying me.

Before I start I know this must have been answered somewhere already, there are thousands of articles written. But I see the game has had some changes and some tricks do not work anymore, that why I choose to ask this myself.

—

One method I know that kept the spiders away is just simply putting torches on the roof, but I thought it was ugly.

When looking up mod-spawning techniques I thought I could use an inverted technique to keep them away.

I heard that mobs don't spawn on half-blocks or glas, well I thought that would make a great roof. My home is made of wood so I choose a wooden half blocks. I did it like this:

x = wooden half-steps    
O  = glass

x x x x x x x x x x x
x x x x x x x x x x x
x x O O O O O O O x x
x x O O O O O O O x x
x x O O O O O O O x x
x x O O O O O O O x x
x x O O O O O O O x x
x x O O O O O O O x x
x x x x x x x x x x x
x x x x x x x x x x x

The half steps and the glass make for a nice roof. Well lit and it looks good from outside.

Well that night I heard the sound again, I went upstairs, and there was a spider staring at me from the roof.

—

NOTE: I do not think they spawn and climb on the roof, because when I
had the torches on the roof everything was fine. The sides my home are
well lit.

Best Answer

Well, indeed mobs don't spawn on glass or slabs (half-blocks). The way you describe it, that spider couldn't have spawned on the roof. There is not much more to say without actually seeing the house and its surroundings. Is it possible that the spider tracked you from outside and climbed on the roof (unlike other mobs, spiders can track you through walls)? Is it possible that the spider spawned on a nearby cliff or tree and fell on the roof?

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