Toronto's downtown is so packed that we're putting buildings on top of buildings, and one upcoming project aims to add a staggering 37 new levels on top of an existing 16-storey Mad Men-era heritage office building at 200 University Avenue.

The proposal from GWL Realty Advisors was first revealed in 2022, and has evolved through appeals and closed-door negotiations in the years since.

GWL's proposal to add new residential levels designed by KPMB Architects atop the early 1960s office building designed by legendary Canadian architect John C. Parkin ran into resistance from City planners, and was appealed to the Ontario Land Tribunal (OLT).

Developer wants to plop 33 new levels on top of a Toronto office tower https://t.co/1C4uzof17b #Toronto #TorontoRealEstate #RealEstate

— blogTO (@blogTO) June 16, 2022

Most recently, the developer and City have formulated a settlement agreement that would retain elements of the existing office tower that had previously been proposed for demolition, resulting in the forthcoming approval of a reworked plan.

The current settlement offer, expected to be approved by the City, is actually even taller than the previous scheme. The existing floors and 37 new levels add up to form a 53-storey tower rising to a height of 188.5 metres.

The plan would see the existing office tower retained entirely, though its office uses would be converted to residential, including affordable housing. Its exterior cladding would be stripped away and replaced with a new curtainwall glazing system designed to match the existing materials while adding the required ventilation openings for residential conversion.

The mechanical penthouse's lantern feature is planned to be restored with new backlit translucent white glazing as originally designed.

New levels would be suspended five metres above the existing tower's set-back lantern feature and a dizzying 17 metres above the main tower's roof.

So, how do you engineer an existing building to support a new tower roughly double its height?

Planning documents explain that the tower's existing perimeter columns will be altered to increase their bearing capacity, extended upwards, and re-clad in aluminum shrouds to match the current design.

The new tower's design incorporates a truss system, eliminating the need for the existing columns to be extended above the heritage building. However, the tower addition's new elevator and stairwell core will require the demolition of interior heritage attributes like the main lobby.

Some lobby elements like travertine wall panelling and granite flooring will be salvaged and reinstated within the new complex's residential lobby.