How does land demolition work in ArcheAge?

I wanted to know precisely how land demolition works in ArcheAge (EU/NA version, published by Trion), in particular for the unfinished construction yard.

When someone puts on land a house design, you have to pay taxes for deposit and bring there constrution materials. If you don't do anything, after how much time the land return free? I read the sign on the contruction yard itself that tells "protected until...", what does it mean? That the land will return free at expiration of that time, or maybe after that another week starts for the final countdown?

Thanks for any replay/information.