Visible displacement in the stone cladding was occurring in this post modern granite-clad building. A detailed building enclosure investigation completed by Crosier Kilgour & Partners confirmed that moisture penetration, from both condensation and wind-driven rain, penetration were inducing frost-jacking in the panels. The displacement had fractured the stone kerfs, used to restrain the stone against lateral movement. The problem was significantly aggravated by the absence of any sheathing behind the stone cladding.
The remediation program consisted of removal of every stone panel on the building; the granite itself was generally in good condition, thus, a decision was made to accommodate re-installation of the granite cladding in order to preserve the appearance of this architecturally significant building. The program therefore consisted of identification and labeling of every stone panel on the exterior, followed by careful removal and storage of the stone panels. The asbestos over the steel framing was removed, followed by installation of a steel stud framework to accommodate new exterior sheathing.
Galvanized structural steel sections were installed to support the granite stone cladding panels; as the stone thickness was less than 60 mm, every stone panel had to be individually supported. A continuous spray-applied air/vapour retarder membrane was installed followed by spray-in-place polyurethane insulation. The stone cladding was then reinstalled incorporating a pressure-equalized rain screen.
The work was completed under our design and specifications which permitted continuous use of the building. Air monitoring was utilized in order to validate that no communication was occurring between the exterior construction and the interior work environment. The project commenced in 2011 and was completed in 2013 at a construction cost of approximately 12 million dollars.