Dividing large apartments into micro-studios and student rooms

Expansive, over hundred-square-meter apartments are very difficult to rent as a whole. Reworking their layout into several micro-studios or lockable student rooms is an engineering way to drastically increase profitability from every meter (so-called cashflow maximization). It requires capital for plumbing renovations, but the returns outclass the market. The best 'semi-finished products' for such investments are old tenement houses sold directly, where negotiation flexibility is usually the highest.