(1) If the duration of a superficies is to be determined by a contract, the period shall not be less than:1. 30 years if the superficies is for owning buildings made of stone, lime, brick, or strong buildings similar to the above, or for owning trees;2. 15 years where the superficies is for owning buildings other than those mentioned in the preceding subparagraph;3. 5 years where the superficies is for owning structures other than buildings.
(2) If any period less than that mentioned in the preceding paragraph has been determined, it shall be extended to that period mentioned in the preceding paragraph.