Minecraft wiki entry for Safe_home, associated text: A harsh rule in surviving in the Nether is never to build a netherrack house as netherrack is highly flammable and ghasts will probably tear apart your house before you can even admire your beautiful netherrack mansion. (Think: Breaking netherrack with fists is quicker than punching stone.) Another harsh rule to follow is not to leave ANY gaps near the bottom of your house, or else fire will be able to come in if ghasts attack the ground around your house. It's strange, but ghasts seem to not be able to see through glass.