A portion of the peripheral wall outside the Eastern Quadrangle of the Victoria Memorial Hall, which has tilted and been on props since July last year, is yet to be repaired.

The cause of the tilt — about half an inch — is yet to be ascertained, officials said.

The monument is undergoing a major restoration. While the refurbished and redesigned northern galleries will be inaugurated by Prime Minister Narendra Modi on Saturday, long iron props will continue to support a part of the outer eastern wall.

Raghavendra Singh, CEO, department of museums and cultural spaces, under the culture ministry, was at the Memorial on Friday to announce that the renovated Metcalfe Hall, Currency Building and the Belvedere Estate in Alipore would be dedicated to the people of the country as cultural spaces. The Prime Minister is set to inaugurate the newly renovated spaces on Saturday, along with the refurbished Victoria galleries.

As for the tilt in the wall, Memorial curator Jayanta Sengupta said: “Some marble blocks have to be removed and pits dug to ascertain why the wall has tilted. It is a peripheral wall and has no connection with the actual monument.”

Structural engineer Himadri Guha, who has been consulted for repairs, has sent his report to a technical committee of the Victoria Memorial Hall.

The committee is chaired by National Council of Science Museums director A.D. Choudhury and includes Sanghamitra Basu, a professor of architecture at IIT Kharagpur, and Rajesh Deoliya of Central Building Research Institute.

“The wall has shifted about half an inch. As a result of the tilt, marble claddings are coming loose,” said Guha.

The committee has advised Guha to dig test pits and channels in the wall to find out the reasons for the tilt. The tilt was first noticed in July. It was decided that the pits would be dug after the monsoon was over.

“The wall has tilted because moisture is trapped between the foundation wall and the marble wall. The gap in between is filled with rubbish, where the moisture is trapped. The trapped moisture is building pressure, resulting in the tilt. The moisture needs to be drained out,” said Guha.

When asked if the wall needed to be dismantled and constructed again, Guha said he saw no reason to do that. “The monument is quite a sophisticated construction. Its architect William Emerson was way beyond his time.... A little problem here and there is normal.”

Asked how the moisture will be drained, the engineer said: “There are internal chimneys or vertical manholes in the wall to drain out water. One has to see why these manholes are not draining the moisture out. That is why we have to dig pits in the plinth and see what is happening. We also need to find out what the method of construction was. If there are any steel joists holding the wall up, we need to see whether the joists need to be replaced. And if there are no joists, we need to find ways to drain out the water through those vertical manholes.”