An architect's rendering of the interior of the glass-domed temporary House of Commons chamber. The $42-million project is to be completed by 2018. (NCC)

The federal government has approved plans to build a magnificent $42-million glass dome on Parliament Hill as a new home for the House of Commons — a temporary one.

The Commons will be moved to the fancy new digs while the existing chamber on Parliament Hill is being renovated, a process expected to take about seven years.

MPs and their parliamentary seats will then be moved back to the current chamber, and the soaring glass dome renovated at further expense to house three parliamentary committee rooms.

The federal Public Works Department claims the project will cost $42 million, but won't say what is included in that amount.

A number of experts familiar with the project have told CBC News that the temporary glass-domed Commons will almost certainly end up costing Canadian taxpayers well over $100 million.

And the Senate wants its own glass dome during renovations to the upper chamber. Officials say that project would likely cost taxpayers as much as the temporary quarters for the Commons.

'Everything they do around here costs 10 times as much as it should and takes 10 times as long … Guaranteed they will screw it up.' —NDP MP Pat Martin

New Democrat MP Pat Martin called the plan to move the Commons into the temporary home "the genesis of a boondoggle."

"Everything they do around here costs 10 times as much as it should and takes 10 times as long … Guaranteed they will screw it up."

The glass dome for the Commons is all part of an extreme makeover of the crumbling Parliament Buildings, a rapidly growing government money pit that is already years late and more than 1,000 per cent over the initial budget of $465 million.

While the government now admits the Hill restoration could cost up to $5 billion, Auditor General Sheila Fraser recently warned the final bill could be much larger.

A major part of those overall costs has been creating elaborate temporary offices for MPs and parliamentary services — facilities such as the Commons dome — while the Hill is under renovations.

A 'crystal palace'

An architect's rendering shows an aerial view of a glass dome atop a temporary home for the Commons approved Friday. The facility will be built in the courtyard of the West Block. (NCC)

The National Capital Commission met Friday to give final approval to the design of the glass dome that some federal officials have dubbed the "crystal palace."

The project was officially unveiled by commission architect Linda Dicaire, who said the spectacular dome is necessary to "provide parliament with a dignified chamber and quality facility worthy of Canada's most democratic institution."

An architect's rendering shows an aerial view of a glass dome atop a temporary home for the Commons approved Friday. The facility will be built in the courtyard of the West Block. (NCC)The dome will be built in what is now an open courtyard in the West Block of the Parliament Buildings.

The temporary Commons chamber will have exactly the same dimensions and layout as the existing one, complete with tiered seating for MPs and overhanging visitors' galleries.

The soaring glass ceiling is being designed to match the neo-Gothic architecture of the rest of the Parliament Buildings.

The building will include a cafeteria and an underground tunnel with its own skylights, connecting the temporary Commons chamber to a whole new visitors' centre.

Government officials say they expect the "crystal palace" to be ready to host desk-thumping MPs and parliamentary debates starting around 2018.