Frost Tower is the first downtown skyscraper to be built in San Antonio Texas in nearly 30 years. The 23 story, 460,000 square foot, building broke ground in March of 2017 and opened its doors on July 1, 2019.
The goal was to create an authentic space in the urban core of the city while adding a modern touch to the downtown San Antonio skyline. The architect designed an octagon shaped footprint with each floor stepping in six inches as you go up the tower and, at each corner of the octagon shape, each floor steps out four inches thereby giving the structure a twisting geometric form.
The design team brought the same modern look to the interior of the building by combining glass, stone, stainless steel and strategically placed lighting in the main lobby. Camarata Masonry Systems, Ltd. (CMS) was responsible for the interior stone work on the walls, floors and the security desk.
The architect’s first choice for the lobby floor and monumental stairs was honed Black Lacy phyllite from Norway, but after installing a 400 square foot mock up, it was determined that the Black Lacy material would be too soft for the lobby floor. CMS was able to offer several alternate stones and the design team settled on Via Lactea honed granite from Brazil. Even though the material is quarried in Brazil, we were able to have the Via Lactea fabricated in China. With the change in material and fabrication location, we were able to reduce the cost by more than $500,000. The architect was also very particular about the amount of veining, the size of the veining and the direction of the veining in the Via Lactea flooring. Of the 2,250 pieces (14,000 square feet) over 200 pieces were culled at the factory in China and another 110 were culled on the jobsite to ensure the floor was within the architect’s specifications.
The monumental stairs were designed to give the appearance that the three-inch thick granite treads and landing were floating between the glass handrails. To accomplish this, each piece of stone had to be routed out one inch on the bottom side to hide the steel support while maintaining the three-inch thickness along the exposed edges.
The vein cut unfilled honed Roman travertine on the walls in the elevator lobbies provides a pleasing contrast to the granite floors. The walls were designed with open 1/8” horizontal joints while one-inch stainless steel channel was placed in all vertical joints. The open joints did not allow the wall panels to be stacked; therefore, each piece had to be independently loaded back to the structure. Another challenge with the travertine walls was the extremely large piece sizes. Some of the panels were seven feet tall and fourteen inches wide. Due to this excessive length, some of the stone pieces were not completely flat upon arrival which created additional installation obstacles.
The biggest challenge as the stone contractor was construction of the polished Fior di Pesco marble security desk. The design is octagon shaped like the building and each side is a parallelogram with a “fold” in the center. At each point of the outside of the octagon, five pieces of stone came together from five different directions. With 1/32” epoxy joints, each stone had to be cut and fit with zero tolerance. The architect added a degree of difficulty by hand selecting consecutive slabs from a single block in Italy and marking where each piece would be cut from. Each side of the octagon was to be end matched and identical to all other sides. With limited material selected there was only one opportunity to get each cut right.
The end result of the overall building design and stellar interior finishes provide an inspiring beginning for an old city with new plans for growth and revitalization.