Bollywood star Shah Rukh Khan plans to renovate Mannat, his 27,000-square-foot sea-facing mansion, over almost two years beginning May.The property, built in 1914, is a Grade 2-B heritage structure on Bandstand in Bandra, Mumbai. The actor has sought clearances from the Maharashtra Coastal Zone Management Authority (MCZMA) before beginning the renovation.What rules govern heritage properties in Mumbai, and what permissions does the actor need?What does the Grade 2-B heritage title of the property mean?A property, establishment, site, or space acquires heritage status if it has an architectural, cultural, and/ or historical significance.In the first listing of heritage sites in Greater Mumbai published in 1995, Khan’s property, which was originally called Villa Vienna, was marked as a Grade 3 heritage structure.In a review of the list in 2006, the Mumbai Heritage Conservation Committee (MHCC) of the Brihanmumbai Municipal Corporation (BMC) upgraded the property to a Grade 2-B structure.Story continues below this adThe reason, according to a review note on the report submitted to the MHCC in 2006, was the “architectural value as a seaside villa and associational value with Shah Rukh Khan”.Heritage properties are classified into three main categories – Grades 1, 2, and 3. Grade 2 has two sub-grades, 2A and 2B.Classification is based on both architectural parameters and historical importance.Also Read | Why have Karnataka and Maharashtra stopped bus services to each other’s state?Grade 1 structures are buildings or sites of national or historical importance which also have excellent architectural design. According to rules, these structures need to be carefully preserved.Story continues below this adGrade 2 structures include buildings and precincts of local and regional importance possessing special architectural and cultural merit. And Grade 3 buildings and sites are important for a townscape.Khan bought the property in 2001, and was not allowed to make any structural alterations. He, therefore, built a six-storey annexe behind the original villa and named it Mannat.And why does Khan need clearance from the MCZMA?The property is located at the southernmost tip of Bandra, on a peninsular strip of land called Land’s End, which extends into the Arabian Sea. At the very end of this strip, at its southernmost tip, stands the ruins of Bandra Fort.Considering how close this area is to the sea, property owners have to get clearance from MCZMA, which is the state’s nodal agency to regulate development clearances in the coastal zone.Story continues below this adThe planned redevelopment work in Khan’s property will add two additional floors to the annexe, which will increase the built-up area by 616.02 sq metres. Since the height of the property will increase, clearance from MCZMA is required.“Any kind of property construction or redevelopment work will require prior permission since the height of the property as well as the extension will have to remain within certain permissible limits,” an official said.Also, the renovation must be carried out in a “sustainable” way, the official said. “For example, debris can’t be dumped in the sea. For these reasons, prior MCZMA permission and declaration is required,” he said.