I am building a bridge through the Nether, out of Nether Brick. The only issue, is that the bridge enters the bounds of a Nether Fort, meaning that Blazes, and Wither Skeletons can spawn on it.

I know that they cannot spawn on right-side up stairs, and half slabs, if placed on the ground (half a block below the normal block height). This is due to the block not considered as being a "full" block.

However, if I place stairs upside down, will this still be the case?

  • I recommend the series "will it spawn" (sometimes included in "mythbusting") by Xisuma. Sep 17, 2017 at 9:47

1 Answer 1


Mobs can spawn on top of upside down stairs. The top of the block is solid/full so it is counted.

Here is the wiki on the subject:

the block directly below it must have a solid top surface (opaque, upside down slabs / stairs and others)

The wiki also states that for a blaze specifically:

the light level must be 11 or darker

  • Yes. I mentioned it because I have forgotten it a couple of times and had blaze surprise me.
    – IronAnvil
    Sep 17, 2017 at 3:29

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