When First Canadian Place was built in 1975, it was covered in blinding white Carrera marble. Over the years, the city's poor air quality has taken its toll. Rather than white, the building now appears to be a mottled grey colour. Even worse, some of the marble slabs have begun to loosen. In 2007, a slab from the building fell on the building's mezzanine level. Luckily nobody was hurt but clearly something needed to be done.

Brookfield Properties, the current owner of the tower, has decided to replace the marble cladding. Starting from the top and working down, each one of the marble slabs on the faces of the building will be replaced with textured spandrel glass - essentially opaque panes of glass that will feature a triangular pattern to create visual depth.

An example of the possible choices and the condition of the existing marble are shown above. The recessed corners of the building, however, will be replaced with bronze sections to give the building a more vertical emphasis. A video of the before and after and a complete description of the process can be found here.

The good news is that after months of prep work, the actual recladding has begun. You might have noticed that the two-storeys worth of scaffolding has been moved to the top of the building. It's connected to the elevator which moves construction workers and materials to the top floor. The scaffolding will move down the building every two weeks, after the completion of two floors. To complete all of the building's 72 stories will take until the end of next year.

There are some people who are disappointed by the particular choice of recladding material. The AON Center in Chicago was built around the same time as First Canadian Place, and was similarly clad in Carrera marble. When pieces of that cladding started to fall off, that building was reclad in granite, rather than fritted glass. Why isn't FCP being reclad in a similar material? As the city`s tallest office tower and a major landmark, it should be visually impressive, and the concern is that the fritted glass will not be as striking.

And what is being done with all of the marble slabs? Brookfield Properties has not given full details, but you can inquire about snagging a slab or two. As part of the LEED certification process, the renovation gets points for repurposing the leftover marble. Environmentally sustainable projects, art installations and charities will likely be favored. If you have an appropriate project, it may be a great way to reuse a piece of Toronto`s history.

All images by Matthew Harris except for rendering of reclad FCP from Brookfield Properties.