Slab

Slabs are half-height versions of their respective blocks.

Breaking
Stone-type slabs and smooth blocks require a pickaxe to mine. Wooden slabs can be mined with anything, but an axe is quickest.

Most slabs drop themselves when broken. The exception is petrified oak slabs, which drop normal oak slabs.

Double slabs drop 2 of their respective single slabs, even when mined with Silk Touch. $$, double slabs are completely unobtainable. $$, they can be obtained through inventory editing.

Stonecutting
Petrified Oak Slabs are the stone-type wooden slabs left from before Java Edition 1.3.1. They are now unobtainable in vanilla survival. However, they can be retained from worlds played in versions where they were legitimately obtainable.

Natural generation

 * Smooth stone slabs generate naturally in strongholds.
 * Sandstone slabs generate naturally in desert wells, and desert pyramids.
 * Spruce slabs generate naturally in igloo basements.
 * Oak, birch, spruce, smooth stone and cobblestone slabs generate naturally in woodland mansions.
 * Dark oak, cobblestone and mossy cobblestone slabs generate in pillager outpost.
 * Oak, birch, spruce, jungle, acacia, and dark oak slabs can generate in shipwrecks.
 * Blackstone and Quartz slabs generate in bastion remnants.
 * Purpur slabs generate naturally in end cities.
 * Villages
 * Smooth stone, oak and cobblestone slabs generate naturally in plains villages.
 * Smooth sandstone and sandstone slabs generate naturally in desert villages.
 * Smooth stone and acacia slabs generate naturally in savanna villages.
 * Smooth stone and spruce slabs generate naturally in taiga and snowy taiga villages.
 * Ruined Portal
 * Stone, stone brick, and mossy stone brick slabs generate in ruined portals in the overworld.
 * Blackstone, polished blackstone, and polished blackstone brick slabs generate in ruined portals in the nether.
 * Nether brick slabs generate in ruined portals in the nether.

Placement
Slabs can occupy either the top half or the bottom half of a block, or both:
 * Placing a slab on top of a block or on the side of a block in the lower half of the side surface creates a bottom slab
 * Placing a slab on the underside of a block or on the top half of the side surface creates a top slab
 * Placing a top and bottom slab of the same type in the same block creates a double slab block
 * It's impossible to place two different kinds of slabs in the same block.

Slabs cannot be oriented vertically.

Behavior


A top slab or bottom slab is transparent to light $$. A double slab is opaque.

A bottom placed on top of a hopper is transparent to items; the items fall through the bottom slab into the hopper. Without a hopper attached below, a bottom slab behaves as a solid surface.

Falling block entities (like sand, gravel, and concrete powder) turn into their dropped form if they land on a bottom slab, as when they fall on a torch.

Mobs see a slab as a full block when pathfinding. They can spawn on top slabs and double slabs, but not on bottom slabs. This can be used to prevent mob spawning in certain areas, such as mob farms.

Generally, the top face of top slabs, the bottom face of bottom slabs, and all faces of double slabs are handled as solid blocks. Due to this, blocks that require a solid surface for placement can be placed on these faces.

Double slabs are handled as a single block instead of two different slabs; as such, breaking one destroys the whole block and drop two slabs, as opposed to breaking only one slab within the block. "Double slabs" that are not aligned to the grid (i.e. a bottom slab on top of a top slab) are handled as separate blocks and are broken individually.

Redstone dust placed on a top slab receives signals from redstone dust one block lower and adjacent, but cannot transmit signals down to that block.

$$, mobs standing on bottom slabs with air or another bottom slab below fail to pathfind correctly. They often end up spinning around in a small circle when they try to move.

Due to the way blast rays propagate from an explosion, bottom slabs provide extremely effective absorption to explosions directly on top of them.

Sneaking reduces the player's hitbox height to 1.65 blocks $$, and so does not allow the player to walk over a bottom slab with one block of air above it, which is 1.5 blocks of space. $$, however, a crouching player's hitbox is exactly 1.5 blocks, allowing the player to fit through such a gap. A player cannot walk from a block of soul sand directly up to a bottom slab without jumping – this applies not just to soul sand, but to any block $7/8$ of a block high or shorter, because the maximum step height of the player is 0.6 of a block. The player can walk off a bottom slab while sneaking, because the sneaking prevents falling only when the distance is higher than one half block.

If a single slab is placed in a water source block, the empty half of that slab's block is waterlogged. If a slab is placed in flowing water, a pocket of air is created in the unfilled half of the block. If the player's head is in this pocket, the player can breathe and see as clearly as from an air block. If a single slab is placed in between two water sources or waterlogged blocks, the slab becomes waterlogged. This also happens when a water bucket or a bucket containing a fish is used on a single slab. Double slabs cannot be waterlogged.

A minecart on powered rails is not repelled by a slab, although it is repelled by a slab with a minecart on top.

Fuel
Wooden slabs can be used as a fuel in furnaces, smelting 0.75 items per slab in, and smelting 1.5 items per slab $$.

Note Blocks
Wooden slabs can be placed under note blocks to produce "bass" sound.

Stone slabs can be placed under note blocks to produce "bass drum" sound.

ID




Block data
$$, slabs use the following data values:


 * Double stone slab


 * Double stone slab 2


 * Double stone slab 3


 * Double stone slab 4


 * Stone slab


 * Stone slab 2


 * Stone slab 3


 * Stone slab 4


 * Double wood slab


 * Wood slab


 * Crimson, warped, blackstone, polished blackstone and polished blackstone brick slab

Trivia

 * Any light directed through a slab does not affect any block's light values north of the source.
 * Whereas 1×1 dents in a flat floor using slabs are darkened as one would expect, 1×1 dents created using 2×1 or 2×2 stairs darken less, due to having fewer surrounding solid blocks.
 * When water or lava are on top of an upside-down slab, the water dripping particles appear in midair below the slab instead of from the slab itself, this was fixed $$ 1.13-pre7, but will not be fixed $$.
 * When a TNT placed on a slab explodes, its blast radius is greatly reduced. ( In some cases, only the slab is destroyed. )
 * As with the previous trivia, End Crystals and Creeper explosions will also be weakened if the explosion happens on the slab.
 * Slabs are the most efficient way to produce renewable charcoal fuel $$. 3 wood blocks &rarr; 12 planks &rarr; 24 slabs for smelting 36 wood blocks into charcoal, which in turn can smelt 288 items. $$, the most efficient way to produce charcoal is to use planks as fuel to smelt wood blocks without crafting the planks into slabs.
 * $$, for each slab, the Journal states: "Useful for creating shallow steps and flooring but wait there's more! Slabs are also a great way to hide redstone wires."