The federal government is planning to spend $2 million to beef up security at the historic home occupied by Prime Minister Justin Trudeau and his family.

The Royal Canadian Mounted Police will spend  $1.6 million to upgrade security at Rideau Cottage. The National Capital Commission (NCC), which is responsible for Canada's official residences, will contribute $390,000 to the upgrades.

The spending is outlined in a small item buried in the 101-page supplementary estimates document tabled in Parliament Tuesday and still awaiting parliamentary approval. 

Trudeau has opted to live in Rideau Cottage on the grounds of Rideau Hall instead of the prime minister's traditional residence at 24 Sussex Drive, which is in need of major repairs.

Asked why security at Rideau Cottage is only being upgraded now — more than a year after the Trudeau family moved in — RCMP spokesperson Brigitte Mineault said the force assesses security risks on an ongoing basis.

"This measure is simply part of the RCMP's continuous review of measures and best practices and is aimed at providing the prime minister and his family with the same level of security they would receive at 24 Sussex Drive," she said.

The problem, said Mineault, is that Rideau Cottage wasn't designed to house a prime minister. In recent years, it usually housed the secretary general to Canada's governor general.

"Since Rideau Cottage was not purposely built for the prime minister of Canada, security enhancements were deemed necessary to ensure a level of security necessary for the prime minister and his family."

Trudeau and his family outside of Rideau Cottage, Halloween 2015

However, Mineault would not say how exactly the government is going to spend the $2 million, saying only that the upgrades won't be there forever.

"The physical features of these security enhancements are recoverable and removable: in other words, they are not permanent," she said. "They will be built with the utmost respect for the natural, heritage and symbolic character of the Rideau Hall grounds."

The 22-room Rideau Cottage, built in 1867, is a recognized historic site located on the sprawling 88-acre grounds of Rideau Hall. In 2013, the National Capital Commission carried out $400,000 worth of renovations to the foundation, roof, ceiling, as well as mechanical and electrical systems to make the building energy efficient.

Auditor General report 20080506 TOPIX

Trudeau grew up at 24 Sussex Drive, the traditional residence of Canada's prime minister, but has chosen instead to install his family at Rideau Cottage while the National Capital Commission prepares a major renovation of 24 Sussex. (Tom Hanson/Canadian Press)

Meanwhile, 24 Sussex Drive sits largely unoccupied across the street from Rideau Hall – used mainly by staff and the RCMP assigned to guard it. The Trudeau family has reportedly occasionally used the indoor swimming pool installed while Pierre Trudeau was in office.

In August, documents obtained by Radio-Canada revealed that upkeep to 24 Sussex cost taxpayers $180,000 over a five-month period.

In 2008, an auditor's report revealed that 24 Sussex needed major repairs. However, that did not deter former prime minister Stephen Harper and his family from continuing to live there until he lost the 2015 federal election.

Inside renos at Rideau Cottage, Justin Trudeau's new residence0:34

An architect and developer's report, obtained by iPolitics in November 2016, estimated renovations and repairs to 24 Sussex could cost almost $38 million.

Wednesday, NCC officials were tight-lipped when asked about plans for the residence.

"The National Capital Commission continues to work with its federal partners, including the RCMP, to develop a plan for the future of 24 Sussex Drive to ensure the government is able to make a prudent and informed decision," wrote Nicholas Galletti, director of strategic media for the NCC, in an e-mailed response.

"This includes issues related to security, functionality, environmental sustainability, universal accessibility and heritage preservation."

Asked when that plan would be ready, Galletti would only say "further information will be available in due course."

Elizabeth Thompson can be reached at elizabeth.thompson@cbc.ca