West 17th Lofts Rehabilitation
Entuitive's Role
Prime Consultant
Location
721 Aspen Meadows Hill SW, Calgary, Canada
Client
West 17th Lofts Condominium Corporation
Size
45,120 ft², 44 luxury four-storey townhomes in seven blocks
Budget
$6.9 M
In 2014, Entuitive was retained by a previous client, the condominium corporation of West 17th Lofts in Calgary, Alberta, to conduct a full building envelope condition assessment of the entire townhouse complex.
After careful investigation, and worrisome findings that necessitated immediate attention, our team prepared a comprehensive design package for the replacement of all affected structural and building envelope components, including all cladding, windows, and doors.
Our vision was to repair the safety and performance of the building envelope of each home, thereby restoring the value of the properties as well. The project was a true test of structural knowledge and ingenuity, requiring a workable solution for the fully occupied townhouse community.
Because major structural supports were undersized, the building envelope was not sealed properly, allowing moisture ingress. The moisture caused the severe decay of internal beams, columns, and timber framing throughout the structure. Certain areas exhibited levels of organic growth that were hazardous to occupant health.
We used a high-level of slag in the concrete. This meant we had a high percentage of recycled content in the mix, greatly reducing embodied carbon emissions for cement manufacturing.
The project optimizes human comfort with radiant heating and cooling (with hot water coming from the District Energy building two blocks away) while minimizing the need to condition outdoor air thanks to a dedicated outdoor air system (DAS). The system supplies outdoor air to the space at a low level and low velocity, known as displacement ventilation, which efficiently removes unwanted heat and contaminants as the supplied air rises through the space.
The nodes of the 55-metre truss consist of five piles of 100-mm-thick plate. The largest node weighs the same as some battle tanks at 12 metric tonnes. The two diagonal web members, which support the largest compression forces of 33 and 38.5 meganewtons, comprise four piles of 100-mm solid plate. These were welded using partial joint penetration welding along the edges in the shop, requiring high pre-heating and careful post-heating to minimize potential weld-induced stress concentrations and indicators. The site welding required for connecting the truss web members to the largest node took approximately 150 man hours to complete over multiple days, with induction heaters running 24 hours a day.
The library’s entryway is designed to resemble a Chinook arch cloud formation. The three-storey, 18-metre-tall trusses feature architecturally exposed web members, with the largest members comprising four built-up piles of 4” thick plate. The largest truss spans 55 metres, is curved, and supports another truss spanning 30 metres.
The library sits over Calgary’s busiest light rail transit (LRT) line. This presented many unique structural challenges. The curved shape of the LRT line helped achieve the library’s distinctive shape by mirroring the curve along its longitudinal axis. Cost-effective structural solutions involving long-span floor framing and long-span, mega-trusses provided large, column-free spaces at the main entrance and oculus.
Each truss was too long, too tall, and too heavy to ship as one piece. As such, each piece was individually shipped and erected 10 metres above grade and temporarily braced back to the concrete cores that were advanced first. A temporary bracing system was used to stabilize each truss as additional floors were cast. Welded in shop along the long edges in partial joint penetration, the truss pieces required careful pre- and post-heating to minimize potential weld-induced stress and steel cracking. Two-end dialog b members support the largest compression forces of 33 and 38.5 meganewtons.
Meet the Team
A True Test of Building Envelope and Structural Ingenuity
Home
Team
Constructability
Challenge
Constructability
Building Envelope
The previous year, Entuitive had been retained by West 17th to consult on a roofing investigation and replacement project. During this project, the project principal, Brian Shedden, noticed that many garage door headers exhibited significant deflection. The firm was brought on the following year to investigate this issue, which revealed major structural and building envelope issues.
Challenge
Vision
The beams above each of the garage doors in the townhouse complex, as well as other major structural supports for each unit, were severely undersized, causing the structures to sag. This structural failure caused multiple failures in the building envelope.
Structural
Structural
As multiple undersized beams had to be replaced, the structural team worked closely with the contractor to ensure that the means and methods were the most economical and feasible, while ensuring that the replacements would not adversely impact the new building envelope components that would be installed overtop.
The extensive decay to the timber framing required much of it to be replaced in-situ, including corrections to poorly executed carpentry work found once the walls were fully revealed. Some of the decay was so severe that tools were not required to remove the affected components. (The team could remove them by hand.)
Building Envelope
The issues with the building envelope were extensive and significant. Poor installation methods coupled with the shifting structure resulted in open joints in almost all locations. As such, the building envelope repair had to start at the level of the timber studs, moving outwards step by step. This required our team to develop a significant number of details to deal with the differing conditions encountered. The team documented the existing conditions during demolition to showcase the rationale behind such extreme rehabilitation, both for the owners and the board of directors.
The design also incorporated proper drainage and airflow to ensure the underlying components could breathe. The material selections involved a significant undertaking to find matching materials and products, which were so successful the complex today does not look like it has undergone any significant rehabilitation work. This was a primary directive from the condo corporation.
Building Envelope Remediation
Randy Thesen
M.Eng., P.Eng.
Principal
Structural Remediation
Brian Shedden
BSS
Principal
Heather Elliot
P.Eng., LEED Green Associate
Associate
Nicholas Fuss
A.T., P.Tech. (Eng.)
Building Envelope Specialist
Nicholas Fuss
A.T., P.Tech. (Eng.)
Building Envelope Specialist
Jamie Wentjarv
Building Envelope Specialist
Robert Paquet
P.Eng.
Engineer
Post-Construction
At one point, there was so much scaffolding on the project that other contractors were complaining they were having difficulty finding any available in Calgary!
Interesting Fact
Throughout construction, additional issues with the structure were found. The most shocking being the bolts through the structural C-channel that had simply been glued on to the surface to mimic the appearance of proper fastening.
As multiple undersized beams had to be replaced, the structural team worked closely with the contractor to ensure that the means and methods were the most economical and feasible, while ensuring that the replacements would not adversely impact the new building envelope components that would be installed overtop.
The extensive decay to the timber framing required much of it to be replaced in-situ, including corrections to poorly executed carpentry work found once the walls were fully revealed. Some of the decay was so severe that tools were not required to remove the affected components. (The team could remove them by hand.)
Throughout construction, additional issues with the structure were found. The most shocking being the bolts through the structural C-channel that had simply been glued on to the surface to mimic the appearance of proper fastening.
The envelope components were upgraded with higher performing breathable membranes and self-adhered products around penetrations, while the windows were upgraded to more thermally efficient fibreglass frames.
The existing, poorly secured masonry, which could be pushed over by hand during demolition, was replaced with new masonry that met industry standard securement and reinforcement.
Once construction had begun, Entuitive attended the site daily, sometimes multiple times a day, to monitor progress and react to unanticipated site conditions and unforeseen issues. The extensive and severe nature of the deterioration required a high level of responsiveness to keep construction on schedule while maintaining a high degree of workmanship.
Following completion of the rehabilitation work, the townhouse complex still had a number of remaining issues related to the courtyard and other areas. The board retained Entuitive on an on-call basis to investigate any and all issues brought up by owners. Entuitive acts as prime consultant, hiring subconsultants and subcontractors on the condo corporation’s behalf to complete work as necessary.
Challenge
Home
Vision
Vision
Constructability
Team
