By David Baxter in Ottawa

The major restoration of Parliament's Centre Block is nearly ready to enter the rebuilding phase after six years of demolition, primary excavation and abatement.

The renovation is estimated to cost between $4.5 billion and $5 billion. Siavash Mohajer, senior construction director with Public Service and Procurement Canada, said that despite inflation the budget estimate remains on track, but rising costs have applied pressure to the project.

The overhaul removed tonnes of asbestos and is bringing the building up to modern day standards and safety codes including for technical capabilities. It's also adding a brand new visitor centre which will serve as the main public entrance to parliament with access to all three buildings on the hill.

The new visitor centre will include an expanded security screening area, which planners say will allow greater visitor access. Currently, the annual tour group capacity is around 350,000 people, but the expanded screening area is expected to double that amount. 

The renovation began in 2018 and is expected to be complete in either 2030 or 2031. The building isn't expected to reopen until 2032, allowing for facility testing to ensure operations are smooth.

The conceptual design for the appearance of the new visitor centre is expected to be finalized in fall 2025.

With the new visitor centre being built underneath the existing structure and around the foundation of Peace Tower, workers are currently installing hundreds of steel supports to hold up the building while the renovations are completed.

More precise excavation has begun to carve out rock and earth for this visitor centre, but it is expected to be a slow process. Dynamite was used to blast away rock during the primary excavation, but that is no longer possible at this point.

Seismic shock absorbers are also being installed to match modern building codes. This work would earthquake proof Centre Block for an up to 6.5 magnitude tremor. 

On top of engineering complexities, the renovation is a massive heritage undertaking. All heritage items that can be removed from Centre Block have been for storage and restoration work if needed. 

This means areas like the House of Commons and senate chambers have been stripped to their bare bones so restoration work can take place. 

"When it does return, all of the heritage elements will come back and it will look mostly the same," Louise Cowley, director of long term vision and plan with the Senate said.

It was deemed that the stained glass windows in the senate chamber held no heritage value, so Cowley said a juried competition will be launched in the future to find Canadian artists to design new ones. 

The revised Senate chamber will also be set up so proceedings can be publicly broadcast. 

Making the buildings fully accessible for mobility devices like wheelchairs does mean public seating in the galleries be reduced. Before the renovation began the House of Commons could accommodate around 580 people, and project director Darrell de Grandmont estimates there will be 100 fewer seats once it reopens. 

Seating for MPs in the House of Commons will also need to change in the future. Under heritage rules, the chamber cannot be made bigger but the amount of MPs will increase by the time it reopens. 

De Grandmont says some considerations include doing away with assigned seating for parliamentarians or getting rid of desks in favour of benches, as is seen in British parliament. 

Some heritage elements are being redone entirely, such as stone carvings on the exterior of the building that are too weather-worn to be restored. 

Sculptor Danny Barber showed off a stone bison carving that will be placed on the west side of the building to replace a damaged original. 

Barber worked on the carving over the summer using hand tools and said he takes great pride in bringing out the fine details from the original, such as the curls in the animal's mane and sheaves of wheat flanking the beast.

"It's easy to kind of get overwhelmed, so you have to break it down into the small pieces so you really have to pull back from the overall design," he said.

"I'm very proud to be working on this project, it isn't the sort of thing you get on our workbenches very often."

Through the deconstruction process, the project team uncovered some previously hidden design elements, like intricately stencilled patterns painted on the walls of the speaker's dining room. 

The decision was made to incorporate these stencils into the renovation, among other changes to capture the original building character. 

"There are areas that had been carpeted over floor, and that floor was the original floor back in the day. It's been really this uncovering of a lot of the history of the building overtime, it's been actually remarkable," de Grandmont said. 

Once work is complete the new Centre Block is expected to be a fully accessible parliament with a new IT backbone built in behind the familiar heritage facade.

Mohajer said that the end goal is to have it be a modern building with new additions that can last for the next 100 years. 

(C) The Canadian Press