GOC376715-CS - Green Roof Envelope System Assessment and Repairs

The Greenstone Building, officially the Greenstone Government of Canada Building, is located on Franklin Avenue in downtown Yellowknife, Northwest Territories. The building is 4 stories, faced in stone with a combination of steel and cast in-place concrete. The roof of the building is a standard 2-ply modified bitumen system over a minimum of 200mm (8’’) of rigid insulation.  In some areas, overlaid onto this system, is a proprietary green roof system. Precast concrete pavers on pedestals further overlap the green roof system in one corner to create a rooftop patio. Other features include “sun tunnel” skylights, a solar hot water pre-heating array and a greywater collection system. Since it was built in 2005, the roof has been experiencing leakage in the East and West wing of the building.

An assessment must be conducted to determine if the green roof should be repaired or replaced. A thermal imaging report has been conducted and results are TBD at this time. The green roof sections are in fair to poor condition and the membrane is due for replacement soon. The patio paver/pedestal assembly is in good condition, although drainage problems with the green roof system beneath are fostering the growth of moss between the pavers. These drainage problems may be causing the reported roof leaks.

The intent of this project is to engage an architect consultant to perform architectural services related to the roof systems. The Consultant will conduct a study on the roof and determine whether or not the roof should be repaired or replaced. The consultant will review the available roof documents and existing drawings, conduct a detailed site inspection, develop an Investment Analysis Report (IAR), perform design development, tender preparation and perform contract administration for the implementation portion of the project.  The IAR should include options for replacing roof like for like (including the living roof areas), removal of existing green roof and installing a conventional flat roof or similar with increased insulation, and an option to convert all roof areas to patio decking with green spaces.