As one of San Diego County’s leading Accessory Dwelling Unit Builders, West Coast Building and Design has built all sorts of beautiful homes and ADU Accessory Dwelling Units in San Diego. West Coast Building and Design offers a comprehensive list of custom home additions and extension services in San Diego. Our San Diego ADU builders can tackle all projects, from big to small, and provide advice on affordable home additions. Get peace of mind knowing that you will have trusted and high-quality professionals submitting estimates for your ADU, Home Additions or Custom Home.