The Preserve Buildings 5, Oak Island NC is approximately 130,000 sq. ft luxury condominium building part of approximately 400,000 sq. ft complex that features 5 apartment buildings and a clubhouse with a pool. The Architect of Record is Darryl Barker of Wilmington, NC. The structure features a combination of reinforced concrete frames and shear walls supporting two-way post-tensioned (PT) flat plates. Using 8” and 10” thick PT slabs allowed the Owner to achieve 5 floors and minimum 9’-0 ceiling height at each level all fitting within the maximum permitted building height. Typical slab span is 28 ft with end spans being as long as 33ft. This building has three wings that range from 3 to 5 stories. Most of the balconies are cantilevered elements with typical 8ft clear span. All stabs were designed in house including punching shear checks and detailing. The seismic site class was initially determined as “F” by the project Geotechnical Engineer, therefore the site had to be remediated with vibro-compaction stone columns and earthquake drains. The building is supported on combination of strip and spread footings.