In the most common case, before you purchase a property in Crete, you should look for a company that offers a two year construction guarantee on a new-built house.
If buying off plan, make sure the company meets the building delivery date given, thus obligating them in signing an agreement (set up by the solicitor representing you) stating the date agreed - or facing penalty.
Penalty is whatever you agree with the construction company for every month they are late in completing the construction of your property in Crete.