[whynotmaybe]

No idea about Lisbon but it was common in Brussels to let an old building "rot" to the point where the owner could destroy it and rebuild a new one. This way, they could build a bigger/better building and sell apartment at higher price than just fix the original building.

Demolition permit are hard to obtain but if your building is too decrepit, the city will force you to destroy it.

[pjmlp]

It used to be common, but then many cities got fed up of it, and now many municipalities have local laws to take ownership for the city if the owners behave this way.

[alvah]

-can't get permission to build due to massive amounts of red and green tape

-the only economically sensible option is to let the building fall into disrepair bad enough that the government lets you demolish

-governments close this "loophole" by seizing your property

and the problem is "the owners behave this way"? FMD.

[vkou]

It's entirely possible that there's non-loophole ways to solve this problem, but when a lot of money is at stake, why would landlords (or anyone else) make effort to be compliant with the spirit of the law, when they can cut corners, and abuse the letter of the law?

[pjmlp]

Well, the owners still have a couple of strikes before the city hall decides to fully take action.