Delta Terra Campus is a high-end gym in San Antonio, Texas. This project had some complexities, and also showed how much creative design work is possible with ICFs. The building is 2,170 square feet with a 640 square foot mezzanine. 93 square feet of Amvic ICFs were used for the elevated interior curved walls at the roof transition for a total of 2,888 square feet of Amvic blocks used. ICF installation took only 12 days out of a total project construction period of 32 weeks. The builders estimate that they saved four weeks of work time by building with ICFs with a savings of $30,000 with ICF to achieve the curves.

This project highlights the true design flexibility made possible by using ICFs. Since concrete can be poured into a curve, it allowed for the direct anchoring of the arched Quonset roof to the ICF wall. The top-of-wall conditions utilize custom details with bent steel anchor plates for anchoring the roof panels to the ICF wall. This design approach very cost-effectively achieves a roofing system without requiring any roof structure or support. “To offset the reaction loads of this particular roof design, the rear lower ICF walls were reinforced with a concrete beam bearing on top of the ICF formwork that includes embeds and additional anchor plates at the lower ICF wall,” explains Laura Catalan, director of marketing for Amvic. “Furthermore, this final design was daring enough to include multiple reinforced cantilevered concrete walls for the creation of four corner windows on this very same façade.”

Challenging Site
The final design showcases a middle entrance with a roof “step-up” formed by two curved and elevated ICF end walls formed and poured 21 feet above ground. This site was challenging because it was a very small 0.39-acre commercial site with an existing building at the rear of the site that took up nearly half the property. The existing businesses also needed to remain operational and accessible during construction. ICFs enabled construction to proceed quickly and in stages. The rear ICF wall was constructed within 5 feet of the property line and was also required to be a fire wall. ICFs helped the project secure code approvals along with additional exemptions from the city due to the 4-hour fire rating this envelope system provides along with the noncombustible characteristics of the Quonset metal roof.

Curved Complexities
While the qualities of concrete allowed for the curved walls, it also took precision and coordination by the ICF installer to ensure the correct radius was established before the concrete pour took place. Due to the Quonset roof panels being pre-manufactured and shipped to the job site in pieces, it was essential to ensure the curve of the ICF walls matched the outline of the roof panels. The architects, Architectura SA in San Antonio, have a lot of experience working with ICFs, so they were able to help ensure these challenges were met. The architects paved the way for the local utility company to issue rebates for ICF construction.

The ICF blocks were pre-assembled on the ground with each piece measured, precut, and marked before being placed in its final location. The ICF end walls of the middle entry roof step-up proved to be an even more arduous task as it required the coordination of the upper roof curve plus precise measurements to the underside of the end walls that also needed to align to the underside of the lower roof outline. “To fulfill this critical objective, the ICF installers created a custom curved formwork capable of holding these end walls in place 21 feet above the foundation,” Catalan says. “In addition, this required an elaborate series of bracing and support to ensure these end walls successfully held in place during the concrete pour.”

Amvic was the preferred ICF brand for this installation given the 6-inch spacing of the stirrup ties, which plays an important role in the cantilevered concrete walls at the building’s front corners.

Advancing Design
The curves of this building were inspired by the aviation industry. The curved lines combined with a Quonset roof application resulted in a sleek exterior design. The roof step-up at the middle entry alludes to the fuselage of a typical aircraft. Four sets of bold corner windows suggest a cockpit. The building’s owner runs an aviation business and the building itself is located less than a mile away from the San Antonio airport. The building is unique and stands out, yet also echoes other local placemarkers. 

This is one of the first projects designed by the architects that integrates a complete commercial Variable Refrigeration Flow (VRF) A/C cooling system combined with an ICF envelope that successfully enables precise multi-zone system controls. Advanced cooling is a necessity in a hot weather state like Texas. 

This project is also significant because it proves that ICFs must be limited to square designs or only straight walls. It also shows that three non-traditional construction materials can work together effectively to create beautiful, sustainable buildings and advance the construction industry as a whole. “Moving forward, this project no doubt has the potential to become the catalyst in triggering a new major change to the local construction industry in South Texas by creating awareness of new and better ways to build our future built environment,” says Catalan.

This project was built in conjunction with our 2021 ICF Light Commercial award winner Delta Terra Square, which was built for the same owner on an adjacent lot. Both of these projects were built and designed by the same team and were managed concurrently while ensuring continuous business operation for two other buildings on these properties. While these two buildings have similarities in the construction systems utilized, the end result are two completely different and daring designs that emphasize different architectural features with the use of ICF.