Welcome to 853 Oak St, a newly completed 2026 contemporary residence in the heart of Costa Mesa, offering a rare opportunity to own a thoughtfully designed and highly upgraded property complete with a attached ADU. The main residence showcases four bedrooms and five bathrooms, with each bedroom featuring its own en suite, providing the ultimate level of privacy and comfort. As you step inside, you are immediately greeted by soaring 20 foot ceilings and expansive windows that flood the home with natural light. The open concept layout creates a seamless flow between the living, dining, and kitchen spaces, ideal for both everyday living and entertaining. White oak vinyl flooring runs throughout the home. The chefs kitchen is equipped with state of the art appliances, custom cabinetry, and quartz countertops, along with a butlers pantry and a secondary prep kitchen, perfect for hosting gatherings or larger scale entertaining. The main level also features a private downstairs bedroom with custom built ins and its own en suite, as well as a stylish powder bath for guests. Upstairs, a striking floating staircase leads to a versatile loft filled with natural light, offering the perfect space for a home office or additional living area. The primary suite is a true retreat, highlighted by 10 foot ceilings, custom cabinetry, and a spa inspired bathroom with dual vanities and an oversized walk in shower with three showerheads. Two additional bedrooms, each with en suite baths and custom closets, along with a conveniently located laundry room, complete the second level. Adding exceptional value to the property is the brand new attached ADU, thoughtfully designed with its own private living space. The ADU features two bedrooms and two and a half bathrooms, with all bedrooms located upstairs, as well as an in unit laundry area. The kitchen is finished with quartz countertops and state of the art appliances, offering a modern and functional living environment ideal for extended family, guests, or rental income. The backyard is designed for low maintenance living, featuring a clean patio space and artificial grass, creating an ideal setting for outdoor enjoyment. A spacious three car garage provides ample parking and storage. This is a rare opportunity to own brand new construction with a versatile ADU, modern design, and exceptional functionality, all in one of Costa Mesas most desirable locations.