Behind the Project: Sierra Place
Sierra Place is an office-to-affordable-housing building renewal project in Calgary, Canada. Recently we sat down with Principal Ian Washbrook and Senior Building Envelope Specialist Andrew Van Bakel to learn more about this exciting project.
Entuitive is providing structural engineering and building envelope consulting services on the project and also consulted on a student-led sustainable performance analysis of the 10-storey, 100,000ft2 building.
Thanks for sitting down with us today, Ian and Andrew. Tell us a bit about this project.
Ian: Thanks for having us. This first-of-its kind project in Calgary, Project Thrive, involves converting a vacant commercial building downtown to affordable housing. M3 Development Management Ltd., the project manager, brought us onboard to complete initial structural and building envelope assessments of the late 1950s building.
The nice thing about Sierra Place is how structurally sound it is. A commercial building tends to have more floor vibration, which is not ideal for residential living, making commercial buildings less well suited to conversion projects. Fortunately, Sierra Place was built using structural steel with rolled sections and does not have open web steel joists meaning the floor is less prone to vibration than some older buildings where the whole floor would shake if you jumped on it. The building also had a decent concrete on steel deck from a fire rating perspective and a floor plate just the right size to make Sierra Place a good building for conversion purposes from a structural perspective.
Andrew: On the building envelope assessment side, we completed two feasibility studies to seek how we were going to convert this building before getting into the design stages.
Sierra Place is interesting since it was built in two parts. On the south and east elevations, there was an old curtain wall system probably from the 1970s without any thermal breaks while in the west and north elevations, it had primarily brick masonry. With a tight budget, we had to collectively decide with the team on what can stay or be upgraded to meet new energy standards and better perform in general. It inevitably was decided that the south and east elevations were going to be demolished, removing the old curtain wall systems along with building new stud framed walls with full exterior insulation, punched windows, and metal panel cladding installed on thermal clips. On the west and north elevations, the cladding is staying and we’re doing repairs as needed so it doesn’t become a safety hazard.
It’s been fascinating since you’re dealing with these old buildings with terracotta blocks on the inside for fireproofing and overall unconventional systems that we don’t use anymore. Ultimately, we’re questioning how we can tie in new systems to these old systems to make them watertight and maintain continuous thermal and vapour planes throughout.
With budget constraints being a challenge, were any other areas of the project impacted and what were some of the other challenges you faced?
Ian: When you convert a building from one occupancy type to another, it basically triggers a code review which could have costly outcomes. If a seismic retrofit is needed, it could cost the project owner thousands or millions of dollars. We did an assessment from the seismic perspective using the National Building Code — Alberta Edition where we were able to show the city that the building performs high not only from a floor loading or residential loads perspective but from a current wind and seismic load perspective. Senior Engineer Justin Fried and I did a study where we built a finite element analysis model of Sierra Place based on existing drawings using the commentary L of the National Building Code to show that the project didn’t require a seismic retrofit. This was a huge win for the owner since they didn’t have to spend additional money that could have forced them to sacrifice in other areas, like the envelope and the finishes.
What we learned from this experience for future conversion projects is how important planning and scheduling is, such as determining the feasibility as soon as possible so that the owners can know early on if they would still like to pursue the building.
Andrew: The project’s schedule was hectic with a quick turnaround between envelope, structural, mechanical, and electrical. We were sending 200-page reports in the span of weeks alongside meeting all the city’s requirements, energy code, and getting the financing. It was important for our teams to be in constant communication and come up with quick solutions to minimize costs as well since our work across multi services affected each other greatly.
What has been your favourite part of the project so far?
Andrew: Personally, a lot of my past experience has been working on envelope restoration projects for existing condo buildings. I was excited to try something new with this conversion project of a high rise building downtown. We were essentially a prime consultant on this one, so we were in charge of managing the mechanical and electrical subtrades as well. It was great to work with so many different groups and see us all work together as a team to meet all deadlines while optimizing building performance versus cost. Seeing it all come together has been rewarding.
Ian: I agree. The exciting part of the project was how many essential roles we had within the development. We were prime on the condition assessment as well as arguably offering four services: structural, building envelope, restoration, and overall project management. I learned a lot from the project management side in terms of soft skills that we will continue to grow upon for future projects.
Any final thoughts on the project?
Ian: It was wonderful to see the media recognition and the positive comments and feedback from the community. Calgary has seen constant vacancy rates increase over the year and we’re now hitting over 30% with downtown office vacancies. We hope more conversion projects will come about and we can find more unique solutions to decrease the vacancy rates in downtown Calgary.
Andrew: We would also like to thank the following teams for their strong collaboration and efforts: M3 Development Management Ltd., PCL Construction, Gibbs Gage Architects, Reinbold Engineering Group, and Nemetz (S/A) & Associates Ltd.. A special mention goes out to PCL, M3, and the city officials who were willing to have multiple preemptive meetings before the final reports came out, seeing one of the smoothest review processes with the city.
Thanks for sitting down with us today. We learned a lot and we’re excited to watch the progress at Sierra Place!