what i call grace period is the timer when building is already in decay state (so destroyable by an other player)

ex 240 h timer, when hit 0, enter in decay state, but with a grace period of 240h where you can still log and refresh if nobody has already decayed the building, and refresh it without having the building collapse by itself

actual state is 240h timer than enter in a 24h decay state, with automatic collapse if you log after the 24h.