The Humayun’s Tomb boasts of a grand double dome of a scale never before seen in India. A double dome is one composed of two shells, with a gap between the two layers to give the building an imposing exterior height and keeping the internal proportions acoustic-friendly. The inner dome is barely accessible; the inner face of the outer dome had suffered almost complete loss of the protective plasterwork. Repair works were undertaken inside the double dome of the tomb for the first time since it was built.
The condition assessment revealed that the outer dome was leaking and the plaster on its inner surface had been completely lost. Conservation works required careful removal of cement from the joints of the marble dome and then filing the joints with lime mortar.
Scaffolding were fixed around the marble dome to ensure high standards of health and safety. Carefully raking of the joints in stonework was carried out using fine tools by skilled craftsmen. This process included removing white cement and accumulations of dirt. The marbles joints were cleaned with water spray to remove dust and other deposits in preparation of pointing works Cavities were identified and grouting with lime slurry and traditional additives was carried out to fill the joints and consolidation of the inner masonry layers. Masonry joints were re-pointed with lime mortar mixed with marble dust. These joints were cured with water for two weeks for appropriate setting of the pointing works.
With the marble stone joints secured from rainwater penetration by lime mortar pointing, the inner face of the outer dome was re-plastered with a protective layer of lime mortar. Scaffolding had to be erected on the lower part of the dome and the inner surface was accessible only through a small opening of 0.8 x 0.6 metre in the neck of the dome.