CREJ

November 2021 — Multifamily Properties Quarterly — Page 31 www.crej.com Construction Precaster’s role begins early for parking projects C olorado’s current real estate market conditions and increasing housing mar- ket needs are pushing the demand for multifamily hous- ing to quickly meet the needs of the population influx. Uses of precast concrete products in multifamily projects are help- ing meet the stringent time, labor and cost goals through the use of podium and wrap-style parking structures. These cost-effective, low- maintenance and durable projects are proving to be easily integrated into neighboring architecture and offer great strength, resiliency and durability. Another important aspect for multifamily projects is the need for reduced long-term maintenance, which can be accomplished by engaging a precaster in the preplan- ning for drainage, snow storage/ removal and traffic coatings. This preplanning offers long-term time, labor and cost savings for the owner. Creating the best parking structure for the site, users and budget that meets all project needs requires a careful balance of all construction elements and a logical design plan from start to finish. Delegated design is a unique situa- tion in the construction industry that requires the collaboration of a struc- tural engineer of record and a pre- caster to provide the engineering and design of a structure with precast components. The engineer of record delegates the design of the primary precast concrete structural system to the precaster. “Delegated design for precast con- crete structures identifies the design responsibili- ties of the EOR and the precaster,” said Jason Lien, execu- tive vice president, EnCon United. He stressed that close collaboration among the entire design team is the most important component for suc- cessful projects. In these projects, precast concrete will interface with other building systems, so it becomes necessary to clearly define designs and demands for these elements. Precast scope and design responsibility will differ on each multifamily project depend- ing on materials used, suppliers and manufacturers, creating a dire need for clear design, schedules and proj- ect expectations. Early involvement with a precast specialty engineer allows for a collaborative delegated design role in the design and drawing process with the engineer who will be responsible for the precast com- ponents of the project. The specialty precast engineer should be brought on from the onset of the project to assist in developing drawings and load paths for the precast concrete system to the building plans and foundations. Using early panelization from the precast engineer, identifica- tion of lateral elements, sizes of pan- els and openings required will assist the engineer of record in understand- ing how to design the foundation system for the loads required and set head room expectations. Each use of precast concrete will determine the amount of planning and the intensity of involvement with the precast engineer. It’s impor- tant to note that the size of the proj- ect and the uses of precast concrete will determine the impact on the overall structure. The specialty engi- neer will communicate the needed support and limitations of the pre- cast system to the team and will be able to design and explain how the components will impact the remain- ing building systems existing outside of precast scope. From the initial conception of design until the park- ing structure opens, a host of choices must be made that will affect the final design and cost of the project. Precast concrete is a high-perfor- mance product and system that can be used to meet the needs of this growing multifamily market seg- ment due to on-site manufacturing and speed of installation. Precast concrete consists of specialized concrete mixes that are cast into project-specific panels at an off-site plant. The concrete is placed into a mold or form and cured before being removed from the form. Precast components are then transported to the project site for installation. This prefabrication process allows all pieces to be cast in a controlled environment and erected on site, cre- ating one of the quickest and most- efficient building systems available. Durability is the intrinsic value that allows precast, prestressed concrete parking structures to outlive compet- ing materials. The difference is the level of quality in standard concrete mixes. With projects requiring 5,000 pounds per square inch concrete for the 28-day strength, precasters typi- cally need 3,500 psi concrete in eight to 10 hours to be able to turn over the casting beds daily. This 3,500 psi release strength in eight to 10 hours results in mixes with a substantially higher 28-day strength than the 5,000 psi required. The combination of low water-to-cement ratio and heat-cured concrete equals a high- strength, low-permeability, durable parking structure. All of this allows owners and build- ers the ability to effectively meet housing schedule demands while minimizing site and project delays, and reducing overall costs. Precast product advantages can include long- life span, continuous insulation, fire resistance, vibration control, corro- sion resistance, acoustical control, speed of construction, greater quality control and finish consistency with in-plant production. Plant production reduces on-site labor and lowers the job-site safety risk. With construction material costs currently in an unpre- dictable state, precast costs remain less volatile within the market due to local outsourcing of standard material such as cement, rebar and aggregates. This also reduces the risk of supply chain problems that can result from lack of delivery capability from vendors across the country. s koconnell@enconunited.com Kevin O’Connell Director of preconstruction, EnCon United