One example of a problem that may occur after purchasing real estate, as opposed to what was explained at the time of the contract, is when you are explained that "the first floor used to be a garage, but now it can be used as a room.”
There are many properties where the first floor of the garage was used as a store or a normal residence at the time of construction, but there are also many properties that are suspected to be illegally built, exceeding the floor area ratio required by law.
If you purchase an illegally constructed property, you may receive strict instructions from the government that has jurisdiction over the location of the property, or you may have to reconstruct the building in order to make it legal.