Photo by Steve Adams | Banker & Tradesman staff

Tucked between the former Hancock Tower and 100 Clarendon parking garage, the future home of the $400 million Raffles Boston Back Bay Hotel & Residences has literally kept a low profile since site work began in mid-2019.

That’s starting to change, as a rapid phase of vertical construction will clear the way for projected completion in the third quarter of 2022.

“People hear about a groundbreaking and then they don’t see anything for an extended period of time,” developer Jordan Warshaw noted during a recent phone call. “Maybe 30 to 40 percent of the construction schedule is before a piece of steel comes above the ground.”

I haven’t spent too much time in Boston during the pandemic, but I had little trouble finding a parking space on a Sunday afternoon to check out the progress on the 33-story tower which will contain 147 hotel rooms, 146 condos and six restaurants and bars. At one-third of an acre, the Raffles site is about the size of my own suburban property which contains one ranch house, zero restaurants and just one home bar.

Even taking into account Back Bay’s multilayered development history, the Raffles’ designs and construction techniques are unusually complex. Part of the tower will rise above the University Club of Boston building at 426 Stuart St. In a first for Boston, the lobby and check-in area will be located on an upper floor around the building’s midpoint, reflecting the limitations of the slender building base.

Developers Trinity Stuart LLC bought the property – which previously housed the eight-story former Boston Common Hotel and Conference Center – with plans for renovations before opting for a teardown. Trinity Stuart LLC, a partnership of Warshaw’s Noannet Group and Saunders Hotel Group, bought air rights from the University Club and offered another perk to its members in the form of a direct entrance leading into a 10,000-square-foot expansion occupying an entire floor in the Raffles tower.

After painstakingly demolishing the 8-story Boston Common Hotel and Conference Center and separating its walls from the connecting University Club, construction crews began installing dozens of caissons to a depth of 150 feet. Tilt meters and vibration monitors confirmed that the demolition work didn’t have any adverse effects on nearby buildings.

Mark Dowdall, site supervisor for construction manager Suffolk, said crews discovered the remnants of at least three building foundations from previous structures. Dewatering pumps continuously drained the site, which has a water table that’s 14 feet below grade.

Image courtesy of TAT

The Architectural Team of Chelsea designed a 20-foot steel truss that will hang above the 4-story University Club building to support the Raffles’ cantilevered section, with some help from a second truss on the 17th floor. The trusses and a grid of plate girders help distribute the weight of the building resting on the caissons, said Alexander Donovan, a senior project manager at The Architectural Team, in a recent interview.

The Raffles project is the latest in Boston to use cantilevered design to maximize development opportunities.

Built in the mid-1970s, the 16-story Fiduciary Trust building at 175 Federal St. flares out from a narrow base in a design that avoided below-grade construction conflicts with the MBTA Red Line and old Dewey Square tunnels.

More recently, projects have used cantilevers to maximize development opportunities on challenging parcels. Samuels & Assoc.’s parcel 12 air rights project uses a partial cantilever of the citizenM hotel building located at the western end of Newbury Street. Hines’ $870 million office-residential tower at South Station is essentially being built on stilts above the busy commuter rail platforms.

And Boston University’s new Center for Computing and Data Sciences on Commonwealth Avenue uses multiple cantilevers to allow construction of multiple balconies and green roofs, tapping into the recent craze for outdoor amenities while achieving a distinctive “stack of books” profile.

Editor’s note: This post has been updated to clarify the nature of the University Club’s dedicated space in the Raffles tower.

Checking in With the Raffles Boston

by Steve Adams time to read: 3 min