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Wiki isn't always a reliable source of information. What Antonio described doesn't fit the definition of off-plan in both versions of that wiki article.

Долевое строительство is when people who want to buy an apartment invest in the construction of the building they want that apartment in. This way they don't buy a specific apartment but just have...

недостроенный дом is what you're looking for.

Don't use достроенный дом without proper context, which I can't think of off the top of my head. Just say:

дом (был) построен or дом построили.
...