ARCHITECT Quadrangle Architects Limited
LOCATION Toronto, Ontario
How do you add a whole new building to the top of an existing, functioning building in the heart of downtown Toronto? With a great deal of design savvy and a huge amount of planning. Set for completion in 2009, 130 Bloor will feature impressive residential suites, as well as high-end retail and office space. Quadrangle Architects was selected to undertake the project, including the distinct challenge of adding onto the top of an existing building while at the same time renovating the operational floors below. The result of these structural gymnastics is 14 new luxury condominiums, nine floors of office space and one floor of prime retail space.
The crown jewel in the development is the existing 1960s penthouse apartment spread across the 13th and 14th floors. Unique to Toronto, all the rooms open onto a two-storey central atrium and feature high ceilings, perfectly matched travertine on floors and walls, and wood panelling from oak logs brought from England and milled specifically for the apartment. In total, the penthouse is 11,000 square feet plus 4,500 square feet of terrace.
Stacked on top of the penthouse is an asymmetrical tower of seven new storeys, faced in Indiana limestone, containing full-floor luxury suites. The two floors below the penthouse, which were previously used for office space, were cut back to hold four new half-floor residential suites. The existing private penthouse entrance, used by the former owner, connects exclusively to all the residences and a private parking area underground.
The design for the renovation of and addition to 130 Bloor Street West required the undertaking of significant structural work to update and reinforce the existing building, surgically carving up floors 11 and 12 and then, without substantially disturbing the two-storey heritage-listed penthouse above it, adding seven floors of high-end residences. All of this work had to be done while ensuring the office and retail tenants below could maintain their ongoing operations. Quadrangle worked on the existing building for a year before adding floors, including the reinforcement of the building’s footings by drilling micro-piles into them.
The building had to be considerably strengthened before the new floors could be added. The first step was an upgrade of the building’s first 12 floors, including modernizing the mechanical and electrical systems. Then, demolition experts snipped away about a third of the top two levels of the existing building–floors 11 and 12–to allow for the conversion of the old office space into two terraced, residential floors. The interior construction and new structural bracing were creatively concealed in the faade.
The existing building had to be strengthened so it could handle the weight of both the crane and the Indiana limestone slabs, tinted glass and the addition of 1,400 tons of steel. Steel plate was welded to the reinforced beams to give the structure added strength, and the outside walls were also braced. The roof of the penthouse had a transfer truss installed so that what is essentially a separate building could be built over top. Four layered polyurethane isolation pads, bracing the building from swaying too much both vertically and horizontally, were installed to mitigate subway and traffic noise and vibration from travelling through the steel structure to the residential units.
Special care was taken to ensure that any noise from the offices below would not disturb the tenants of the new condominiums above. An extra space was built between the existing building and the new development and included an acoustic ceiling to further reduce noise impact. In addition to that, vibration isolation material was applied to oversized cast-iron horizontal plumbing lines to reduce the noise of running water.
Quadrangle made some significant changes to major elements of the existing building, including changing the original centre-loaded public corridor to a side-loading one to allow for full-floor condominiums.
Another major change Quadrangle made was relocating the mechanical space, which included equipment such as boilers and cooling towers, from floors 11 and 12 to floors 3 and 4.
Construction on the addition of the new floors began in May 2008 and started with the concealed interior construction, the foundation work and the structural bracing of floors 11 and 12. A huge design challenge for Quadrangle was working on the next part of the project, floors 13 and 14, as these floors were occupied by the heritage-listed penthouse. While the majority of the penthouse was hidden safely from construction by being enclosed in protective wood sheathing, access was still required and came via the non-heritage area at the back, which had originally been used as servants’ quarters. A transfer truss was built above the penthouse to transfer the load of the new tower down the selected support points. This transfer truss is essentially level 15 of the building.
A challenge encountered on the 15th floor was the redesign of some of the cross-bracing to ensure that there would be no overlapping of the cross-bracing and the windows being installed. The solution was to install the new levels two floors at a time. This work was undertaken at night so that existing exits could be temporarily blocked off and new ones installed.
Quadrangle met several other challenges with innovative design, including the method by which the cross-bracing steel was brought into the building through temporarily popping out windows, the late addition of a new floor at the 17th floor level and the installation of new, dedicated elevators on floors 11 to 21 to service the residential floors exclusively.
This project offers important approaches in the practice and process of complex, high-density projects. Great inventiveness in logistical planning and technical sophistication is apparent, as are effective resolutions for the isolation of flanking sound. The new condominium units are impressive; they have achieved a very elegant design resolution creating houses in the sky rather than anonymous modules. Constructing new extensions on top of existing buildings will become an interesting trend, and creative solutions such as these offer important lessons.