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Published June 19, 2009
Canadian Funding Corp revealed that field investigations of the building envelope system consisted of visual review, suite surveys, field-testing and destructive test openings. Supplementary investigations included sampling the thickness of the lamina at 21 locations: 48 per cent of the samples failed to meet the minimum standard thickness of 1.6 mm. Fire safety guidelines called for a minimum applied base coat thickness of 2.0 mm, but 67 per cent of the samples did not meet this. Substantial areas of the EIFS cladding failed to meet the manufacturer’s requirements for fire-rating tests and, therefore, fell short of Building Code requirements.

In keeping with Canadian Funding Corporation's overview, it was determined that the original face-sealed window wall system, was subject to extensive water ingress problems, as a result of the face-sealed detailing at the slab band. As the system did not provide any provisions for drainage to the exterior, any water that penetrated the exterior seals was able to flow down to the floor slab and either enter the interior at the floor level or drain over the slab band behind the slab band cover and migrate into the steel stud framing at the underside of the slab.This resulted in damage to the interior finishes and leaks at the head of the window wall.

It was also determined that some of the window types and the large glazing units of the window wall system were non-compliant with Building Codes and good design practices.The glazing in these systems was not the required thickness and posed a danger from human impact and wind loading.

Canadian Funding Corp: Remedial plan and design considerations

Initially, a targeted repair strategy was recommended. EIFS replacement would be done in critical areas—such as the high-risk wall areas at the north, east and southeast elevations—and restoration work would be undertaken in the less affected areas. However, as a result of the supplementary investigation, which indicated that the lamina was too thin, it was decided that a selective repair strategy was not the best alternative.

Instead, the consultant and owner agreed to replace all windows and the window wall system for the following reasons:

    * improved thermal performance and condensation resistance
    * existing extrusions would require modifications to house new sealed glazing units
    * waterproofing the existing window wall system could not be easily carried out
    * only an incremental cost increase for new windows compared to the cost of modifying existing frames, and installing additional waterproofing and new sealed units.

Furthermore, replacing all windows was seen as contributing to improved performance throughout, along with improvements in uniformity, cost-effective unit pricing and speed of work. Lastly, a full window upgrade would provide a tight air barrier, complementing the improved airtightness of the building envelope.
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