The addition to the Chateau will be a condo development.

1.)  "The architect said he feels this is an opportunity to do something amazing, adding this design creates a sense of separation from the current building and allows the expansion to have its own street identity." (From: "Chateau Laurier hosts public meeting on proposed addition" by Michelle Nash Baker, Guelph Mercury Tribune.com, November 16, 2016.)

2.)  Art Phillips, director of development at Larco Investments said the expansion will add 180 apartments to the hotel, which will be designed larger than the hotel's current rooms in an effort to appeal to guests considering longer stays. (From: "Chateau Laurier hosts public meeting on proposed addition" by Michelle Nash Baker, Guelph Mercury Tribune.com, November 16, 2016.)

3.) "The proposed addition will be read more as an independent building". (Cultural Heritage Impact Statement-Addendum-City of Ottawa-ERA Architects-Page 14 of 81.)

4.)  "The owner acknowledges and agrees that should the lands be severed in the future it shall ensure that the owner of the freehold units shall enter into a Joint Use Maintenance and Liability Agreement." (Google: 1 report to built heritage subcommittee 700 sussex - 1 report to Built Heritage SubCommittee, May 23, 2019 - Page 39 of 81.)

5.)  Waste Collection - Separate collection areas will be required for the commercial (hotel) and residential units. (From: "Chateau Laurier Expansion, 1 Rideau Street Ottawa Ontario"- Page 13 of 94 - City of Ottawa Planner, Development Review, Planning and Growth Management.)

6.)  "The distance between the original building and the new addition has also been increased, jumping from 5.9 metres (20 feet) to 18.35 metres (60 feet.)" According to the press release, the increase will allow for the two to be distinctly separate. (From: "Developer unveils another attempt at Chateau Laurier addition"- CBC News, February 18, 2018.)
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 The condo project will alter Major's Hill Park and probably result in the loss of trees between the Chateau property and Major's Hill Park. Information pertaining to the removal of trees has already been included in official 1 Rideau Street documents.
Major's Hill Park
Stormwater and sewer lines will link the new condo to a manhole in Major's Hill Park and deep service tunnels will have to be constructed.
I would not be surprised if the 12-acre park is sold in the future, and that is why local governments do not care about the public views of the hotel from the park:

Committees- Senate of Canada - Proceedings of the Standing Senate Committee on Environment and Natural Resources - Issue 5 - Evidence - February 17, 1998.
  The owners of the Chateau Laurier Hotel wanted the Daly Building land sold to a developer and not preserved as a park.

Two proposals for the Daly Building lot were designated "mixed use" and one proposal was for a hotel. The third project called for a building approximately half the size of the old Daly Building.
Mr. Beaudry: ...One project has components of either condominiums or hotel suites,plus retail stores.
Mr. Emard-Chabot - ...The last time I was here I talked about traffic and the fact that,if we conceive of a park or an open space, the idea of this as a park or a resting space must be put aside. I have here traffic counts taken from 1996 to 1997. In the 12-hour period from 7 a:m to 7 p:m the numbers are consistently from 25,000 to 35,000 vehicles per day.
...
The Chairman:  Do you know the position, with respect to this park (the Daly Building land), of the Byward Business Improvement Area, which I see represents 350 businesses in the area?

Mr. Emard-Chabot: They would be against it...

The Chairman:  I take it that the Chateau Laurier is against it as well.

Mr. Emard-Chabot:  I received a letter last week indicating that they are not in favour of a park.
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No one would dare build residential units beside the Fairmont Le Chateau Frontenac Hotel in Quebec City or change the terrace beside the hotel. The Chateau Laurier terraces will be banned to the public for special occasions.
Le Chateau Frontenac is protected by the United Nations Agency UNESCO.
It is a sad day for Canada when an international agency has to be called in to protect our history because federal and local governments are unaccountable, lacking in vision and do not care about future generations. I am talking about you-
 Parks Canada
The Department of Heritage
National Capital Commission -" We cannot intervene because the hotel is private property."
The Historic Sites and Monuments Board.
The City of Ottawa, especially the Planning Board.
The Mulroney government that sold the Chateau Laurier to the real estate arm of the CPR in 1988.

The City of Toronto refused to let Larco and architect Peter Clewes build high rise towers on a Classified Federal Heritage Building on 1 Front Street West called The Dominion Public Building. The Building is part of the Union Station Heritage Conservation District which includes Union Station, the John Street Roundhouse and the Fairmont Royal York Hotel.

Dominion Public Building, One Front Street West Toronto, Ontario.

It is time to designate Confederation Square in Ottawa a UNESCO World Heritage Site and a Province of Ontario Heritage Conservation District.