The agency has an anticipated $36.1-million budget to retain "a firm of architects" and a multi-disciplinary team of sub-contractors to address the situation.
First, though it will focus on rehabilitating the 80-year-old roof, which will cost around $21.5 million.
From snow and ice buildups and melts over the years, the roof is past the end of its working life, Public Works stated in tender documents on Merx, a procurement site commonly used by the federal government.
Problems being experienced include :water infiltration, loose or missing fasteners, perfororations, failed soldering, missing copper elements, loose flashing, rust deposits, failed caulking and loose caps," Public Works added.
Windows and doors are also in dire condition, the agency stated. "Due to their current poor condition, approximately 240 existing wood windows have been part of an emergency repair project starting fall 2009."
The agency will open the bids in a single-phase process because it anticipates a limited number of submissions, it stated.
The work must "respect the heritage character of the Confederation Building and use a minimal intervention approach to conserve and maintain the integrity of the structure, the historic fabric and character-defining elements," Public Works stated.
Additionally, the work must disrupt employees in the building as little as possible, as "Parliament Hill must be fully operational at all times."
The Confederation Building was built between 1927 and 1932. The 16-storey tower's exterior is little changed from that time, although the interior underwent rehabilitation in 1972.
The fixes Public Works seeks now will extend the building's lifespan until 2026. At that time, the building is slated to be rehabilitated "as a major Crown project."
The tender includes a site visit on Dec. 15. Bids are due Jan. 10, with full approval of the project expected in 2012.
No completion date was published for the expected roof repairs.