Minecraft: Can Mobs Spawn on Slabs? It’s Complicated

Spawn-proofing is an important aspect of Minecraft for everyone playing in Survival mode. Due to that, certain spawn mechanics need to be studied in order to place the most relevant blocks at the most relevant locations in order to stop the mobs from spawning. In one of our previous guides, we’ve covered the mechanics of mobs spawning on transparent blocks, and today, we’re going to cover slabs. Let’s see if mobs can spawn on slabs in Minecraft.

What are slabs in Minecraft?

Slabs are half-height versions of certain blocks in Minecraft. Most blocks used in building in Minecraft have their “slab” versions. When placed on the floor, you can clearly see the difference in height between, for example, a stone block and a stone slab.

There are three types of slabs, top, bottom, and double slabs. Slabs that occupy the bottom part of a block are called bottom slabs, and the slabs that occupy the top part of the block are called top slabs. It’s all very logical.
Two slabs of the same type can be stacked on top of each other to form a double slab that looks like a full block. It behaves as a full block only visually, as other mechanics are much different.

It’s important to differentiate between those three types of slabs since they behave quite differently when it comes to spawning mobs. It’s something that we will cover in more detail in the rest of this guide.

Can mobs spawn on slabs?

Mobs can spawn on slabs, but only two types. Top slabs and double slabs. As we said, it’s complicated. When it comes to placing top slabs, as you can see in the image below, the height difference between a slab and a normal block does not exist at all. Combine this with appropriate light levels, and mobs will start spawning in no time.

The same goes for double slabs as well. Mobs can spawn on double slabs. Since they are the exact height of a normal block, all conditions regarding block height are met, and the mobs will spawn. There is no clear visual difference, and when it comes to height, there is no difference when it comes to full blocks and normal blocks, as you can see in the image below.

The only exception to this slab rule are the bottom slabs. Mobs cannot spawn on bottom slabs in Minecraft. This is due to bottom slabs being obviously very different from full blocks when it comes to height. You can see this in the image below. Even when all other conditions are met, like light conditions, mobs will not spawn due to the missing height of a block.

Can mobs spawn on partial blocks?

No, mobs cannot spawn on partial blocks as well. It’s again due to the height of the block. For example, dirt paths and farmland act like bottom slabs when it comes to height, as they occupy only a fraction of the height that a normal block would occupy.

The same goes for the snow layer as well. Mobs cannot spawn on snow layers due to them adding an extra height that doesn’t match a full block in height and thus disable spawning.

Can mobs spawn on a carpet in Minecraft?

Mobs cannot spawn on carpets in Minecraft, due to carpets having a height difference compared to full blocks as well. Carpets don’t count as full blocks like other blocks that we’ve mentioned in today’s post. Since block height is one of the major prerequisites for hostile mobs spawning, one good way to spawn-proof your shelter is to place carpets all over the floors. As you can see from the image below, carpets are only a fraction of a full block when it comes to height.

And that’s about it. As you can see, the height of a block plays a major role in the conditions that usually spawn mobs in Minecraft. That’s why most “half-blocks” and partial blocks like bottom slabs, carpets, farmland, and snow layers cannot spawn mobs.

However, if the difference between half blocks and full blocks does not exist, and this is the case with top slabs, the mobs will spawn if all other conditions are met.

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