DPR builds its tallest structure to date—the 28-story cast-in-place concrete Allegro Tower in San Diego

Amid the more than 100 development projects currently being planned or under construction as part of downtown San Diego’s redevelopment program emerges DPR’s latest enterprise, the 28-story cast-in-place-concrete Allegro Tower that includes 201 units, 4,000 sq. ft. of retail space, and four levels of subterranean parking.

Building the company’s tallest structure to date, the team took what they affectionately called the “freight-train approach” with DPR and subcontractors working in tandem like a well-oiled machine, pouring a floor a week of this notable mixed-use project. The “train’s” progress was tracked through the stacking chart, a building elevation broken down by level that provided a detailed account of where team members were each week to ensure that the project stayed on its aggressive 21-month course.

“We took it floor by floor— walking the job each day to make sure everyone was doing what they were suppose to be doing and further enhancing quality control,” said Brian Thomason, superintendent for DPR. “With this type of project, if you miss one small detail, chances are you missed it 201 times, so it was important to get it done right the first time.”

From the start, the more than 263,000-sq.-ft. high-rise posed many unique challenges.

Located on a 30,000-sq.-ft. lot in San Diego’s “Little Italy” area, the site offered limited access with the new tower being built right up to the property line, just four inches away from an existing 22-story office building. During excavation of the four-level underground parking, DPR had to underpin the foundation of the adjacent building and coordinate with an owner-enlisted service, which monitored any internal and external movement of the occupied structure. During excavation, the team also uncovered more than 7,500 tons of contaminated soil that was shipped to two different facilities for treatment. A total of 300 truckloads of soil was transported, treated and disposed of properly. At the other end of the building, the roof is crowned with a distinctive 30-ft.-high freestanding “sail” clad with metal panels. The sail was prefabricated on the ground and flown up to the top of the building with the tower crane.

The building also features a wide mix of exterior finishes, including stucco, acrylic, glass fiber reinforced concrete panels, full-height windows, metal panels, granite and exposed concrete that all have various waterproofing requirements. “The variety of exterior finishes called for more than 19 different subcontractors and an extensive amount of coordination,” said Project Manager John Cole. “The best part of the project was when everyone was working together like an efficient factory line, and the ‘freight train’ was racing to the top.”