Notch has changed the way fire behaves. It appears that previously unreachable blocks are now in danger of being set on fire! In particular, those that have no direct contact with the fire block itself:


In this image, the firey block is surrounded by stone on all sides (other than the top), yet is still being ignited by the fire (note: not lava!) below the floor.

What are the new conditions that a block can be set on fire?

  • Hit it out..fire is now so slow. :P May 26, 2011 at 10:12
  • No point, fire only spreads 2 or 3 blocks now before going out, so my structures are safe, I'll just replace with stone where necessary.
    – fredley
    May 26, 2011 at 10:24
  • possible duplicate of Why is my floor on fire?
    – user3389
    May 26, 2011 at 13:21
  • 2
    @Mark not a duplicate, that is to do with fire caused by lava, not fire caused by other fire.
    – fredley
    May 26, 2011 at 14:32
  • 1
    It's always done that. He just made it spread slower. May 26, 2011 at 17:30

1 Answer 1


The rules of how far fire spreads did not change in 1.6, only how fast. The best guide on fire that I've seen is NZPhoenix's:


This thread is currently a basic introduction on the physics of fire in Minecraft. To understand how fire works and spreads, it is important to understand that fire itself is a block. When fire spreads, it doesn't actually spread to a flammable block. Instead, it spreads to an air block next to a flammable block. Only certain air blocks are in range of any given flame, and I call these Flammable Air Blocks(FABs).


Fire has an area of Flammable Air Blocks(FABs) to which it can spread. The pattern of FABs is 3x3x6. Fire can spread twice as far vertically as it can horizontally.

As stated later on:

Sadly, fire cannot simply be encased to make it safe, the way lava can be.

The only way to prevent fire from spreading to something is to have all air blocks adjacent it to be out of range of the fire. If you can't, then you have to put another block there. (Another flammable block will do, but you have to block all of it's air spaces too.)

Edit: As for why it suddenly spread now, when it's slower, when it didn't in any prior version, is because shortly after a fire is created, it's ability to spread disappears, even if the fire doesn't. Most people don't notice this because the fire goes out soon anyway, but contrary to rumor, Netherrack can spread fire too, just not for long, and by the time people put flammable stuff by it, its chance is over.

What most likely happened is that, with the newest update, this spreading timer was reset because of the changes that Notch made, and your blocks either weren't there when the fire was started or just didn't catch fire by chance.

  • This is very strange then, why has the fire reached these blocks now and not before? There are other instances of the same thing in other areas of my map.
    – fredley
    May 26, 2011 at 18:48
  • @redley: See my edit. May 29, 2011 at 12:19

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