Slab

Slabs are blocks that allow the player to change elevation without jumping. They are not as compact as stairs, requiring twice the horizontal space for an equivalent change in elevation. Unlike stairs, slabs do not stop the player's sprinting, which makes vertical elevation equally quick and horizontal speed twice as fast as stairs while sprinting on slabs. Upside-down slabs occupy the top half of their block space rather than the bottom half. To place a slab upside-down, right-click on the bottom of a "ceiling" block, which can be removed after the slab has been placed.

All six types of slab have the same data values; like wood and colored wool, they are differentiated by their damage values: stone slabs have a damage value of 0, sandstone slabs are 1, wooden slabs are 2, cobblestone slabs are 3, bricks are 4, and stone bricks are 5. Damage value 6 is occupied by another, identical stone slab, but with a slightly different double slab form.

As of snapshot 12w17a, single and double wooden slabs will burn down, but previously placed wooden slabs are unaffected.

Occurrence
Stone slabs can be found naturally in NPC Villages lining the roof of a blacksmith shop and inside some of the buildings where they form counters. They are also found in Strongholds where they are used in some of the stairs, ledges and torch pillars. Sandstone slabs can be found naturally in randomly generated desert wells.

Crafting
Slabs can be made from three wooden planks or three stone, cobblestone, sandstone, brick, or stone brick blocks, producing six slabs per crafting operation. There also is a stone slab which only uses the top texture of the normal stone slab, but it can't be crafted. The damage value is 6.

Behavior
Like other partial blocks, slabs are treated as a whole block with other blocks, such as dirt, stone, and glass, and liquids. Two slabs of the same type (e.g. two stone slabs) can be placed one on top of the other to make a single full-size block, but different slab types cannot be mixed in this way.

Sandstone, wooden, and cobblestone double-slabs look exactly the same as their full block counter-parts, but take a longer time to break and drop two slabs.

As of 12w17a, wooden slabs have to be collected with an axe and they are affected by fire.

An unusual property of slabs is that they are non-solid to redstone. This allows one to hide the redstone wiring in a slab covered channel, while still being able to connect to the wire on the side of the slabs.



Mobs cannot spawn on top of single slabs, but they can spawn on double slabs.

Due to the way blast rays propagate from an explosion, slabs provide extremely effective absorption to explosions taking place directly on top of them. Specifically, this is because explosive entities will be lower in elevation when they explode on top of slabs than they would otherwise be on an ordinary block. Although the few slab(s) directly under the explosion will absorb the full force of the blast (with a resistance of 30) as usual, the propagation of damage to the sides will be greatly reduced. If source of the explosion is elevated for any reason at the time of the blast, this protective quirk is lost.

History


Stone slabs were introduced to the game on October 24, 2009, in Classic Survival Test 0.27, whereas sandstone, wooden, and cobblestone slabs were added in the Beta 1.3 update on February 22, 2011 and stone brick and brick slabs were added in the Beta 1.8 update on September 15, 2011.

In Classic and Survival Test, stone slabs could be obtained by mining a coal block because of the lack of inventory and crafting.

Stone slab blocks were called stair blocks before the current stairs were added; after this, they were known as steps (the two forms being single steps and double steps) before all items got official names upon the Beta release.

Before the additional slabs were added, a double Stone Slab would only yield one slab when broken. Since the Beta 1.3 update, all double slabs yield 2 of their respective single slabs when broken. Destroying double slabs with TNT, however, still only yields single slabs (when the slabs aren't simply destroyed by the explosion).

Before Beta 1.3 came out, stone slabs were made with cobblestone instead of stone, but that update introduced cobblestone slabs to the game and changed the recipes for Pressure Plates and stone slabs so that there wouldn't be any conflicting recipes.

Since the Beta 1.8 sprinting feature, stairs stops the player's sprinting unlike slabs.

As of the 1.2 Preview, all types of Slabs can be placed upside down and under blocks; these occupy the top half of their block space rather than the bottom half.

Before Minecraft 1.2, slabs had a 2:1 input/output ratio, i.e. 3 cobblestone would get you only 3 slabs out of the current 6. This is likely due to the fact that the slab types are differentiated by their damage values instead of by different data values, similar to wood, coal or charcoal, and coloured wool.

In weekly snapshot 12w17a, new slabs were added for the four different types of Wooden Planks, replacing the old wooden oak/"stone" slab. The new slabs were vulnerable to fire, but could now be collected faster with an axe instead of a pickaxe. The old wooden slabs did not burn and could only be collected with a pickaxe because they were the same block and shared the same data value as other slabs, except with a different texture. This caused wooden slabs to break faster with a pickaxe rather than an axe. Wooden slabs were also are not affected by fire and had a stronger blast resistance than wooden planks, which made them a useful building material. These properties could be used in SMP to help prevent griefing, and the fact that wooden slabs didn't burn also made it useful for creating houses in The Nether; but since the update, they can no longer be safely used. The original wooden oak/"stone" slab can still be obtained through inventory editing or the /give command.

Dirt slab


Before Stone Slabs were added to 0.26, Notch ran a test of Dirt Slabs. They were never added to the actual game and were only mentioned once. They replaced all dirt blocks and did not grow Grass on top. The words "Half-sized blocks (all dirt tiles, so it gets kinda slow)" were the only words Notch ever said about them.

Bugs

 * Sandstone slabs do not break as fast as normal sandstone blocks do.
 * Sprinting on slabs always makes gray particles, even if one is sprinting on wooden, sandstone or brick slabs.
 * Upside-down slabs are dark when there is a block above it. A normal block beside will emit some light, but the upside-down slab itself will emit no light.
 * Mining a wooden double slab with a pickaxe enchanted with Silk Touch will make it drop only one slab.
 * Due to lighting glitches with the slabs, wheat will be automatically harvested when surrounded by slabs of any kind.
 * Even though the slab is occupying the top half of the block (upside-down) you cannot place things like torches or beds on top.
 * Wooden slabs are treated as stone slabs, as they need to be harvested with a pickaxe.(Fixed in snapshot 12w17a)
 * In creative, when you use pick block on any type of upside-down slab, you get a similar looking slab that places itself upside down no matter how you place it. This slab doesn't stack with its regular form.
 * In Pocket Edition, A wooden slab will appear as a stone slab while in the players hand.