The two most common types of parking garage structural systems are precast concrete and post-tensioned concrete.
Precast concrete utilizes pre-tensioned reinforcing strands embedded in the concrete to support the loads applied. Precast concrete is fabricated off-site and transported to the site for erection by a movable crane.
Some of the benefits of precast parking facilities include a faster schedule; however, check with local precasters to confirm lead-times. Precast concrete offers a factory-controlled environment to ensure higher quality product. Limitations to precast can occur depending on site conditions due to the necessity of the crane to erect the precast pieces.
Post-tensioned concrete utilizes reinforcing strands which are tensioned after placement of concrete. Post-tensioned concrete is formed and poured at the project site often with the assistance of a stationary tower crane.
Benefits of a post-tensioned structural system include higher durability, flatter ceilings to improve weight distribution, and less occurrence of concrete cracking. However, drawbacks include a longer schedule, a more labor-intensive environment, and a more detailed on-site testing & inspection program for quality assurance.
Depending on the location of the site, complexity of the project, and skill set of the local craftsmen, the cost benefit of one system over another will vary.
Occasionally, owners pursue the idea of steel construction for parking facilities. Steel construction is one of the fastest ways to construct a building. However, parking structures are unique buildings in that they are exposed to various elements such as rain and snow which can result in steel corrosion. Proper durability measures must be considered when evaluating steel construction as a structural system for a parking structure.