> For the complete documentation index, see [llms.txt](https://toncraft.gitbook.io/ton-craft-en/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://toncraft.gitbook.io/ton-craft-en/game-mechanics/durability.md).

# Durability

Building durability. Nails are required to restore it.

Each building has a durability rating that decreases by a set amount for each hour of operation.\
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If a building's durability is too low to operate for at least one hour, it becomes unusable until repaired, which requires a specific number of nails.\
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Promo buildings, however, cannot be repaired; once their durability reaches 0, they disappear.