The historic Kalas Mahal, which was ravaged in a fire in January 2012, is inching closer to its restoration.

The Public Works Department (PWD) is all set to start work to renovate the building in Chepauk by July-end.

Officials of the PWD said once the State government’s nod for the project is obtained in a few days, the department would call for national bids for the restoration and reconstruction of the structure.

The structure, built in 1768, is classified as a grade-I heritage building in the Justice E. Padmanaban committee report. The work to restore the heritage structure would be taken up under the supervision of the conservation architect Ravi Gundu Rao who prepared the detailed drawings.

These drawings were scrutinised by the committee comprising PWD officials, Chennai Metropolitan Development Authority’s chief planner and dean of the School of Architecture and Planning.

Ranee Vedamuthu, dean, School of Architecture and Planning, Anna University, who was one of the committee members, said the plan is to restore the original structure using the same technique, and similar materials, as far as possible. “Nearly 80 per cent is likely to be restored as it was, while 20 per cent additions may be made to make the building functional,” she said.

Estimates for the Rs. 14.5-crore project was drawn based on the drawings provided by Mr. Gundu Rao. He said a project of this scale would even merit a global tender. “It is quite a serious and complicated project as a considerable portion of the original building had been damaged or had collapsed,” he said.

However, with limited available records and documentation, he said, to ascertain what the original structure looked like in its prime involved a lot of research. “Robert Chisholm worked on Kalas Mahal, and usually all great architects of the time have a distinct style. We also took Maharaja Sayajirao University in Vadodara, a structure he worked on, as a reference,” the architect said over the phone from Mysore.

He added that the restoration would be a time-consuming process. “It is not a mechanised project and everything is handmade. For instance, the construction of a brick masonry column can take up to two months. When two layers of Madras terrace have to be laid, the second layer can be laid only after the first one dries. Similarly, lime mortar can take up to two months to harden,” he said, adding that removing the reinforced cement concrete (RCC) roofing which was introduced about 20 years back would be a challenge. “The original columns were not designed to take the load of the RCC roof,” he said.

An official said they wanted to complete the work within two years. However, the department is yet to decide on the use of the restored structure. The 18 century structure of Indo-Saracenic style earlier housed the social welfare department, inspectorate of factories and directorate of industries and commerce.

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