What factors affect ADU construction costs?

Several important variables can impact the total cost of an ADU construction project. Site preparation, grading, drainage requirements, and utility connections are often major considerations, especially for detached structures. Interior features such as kitchens, bathrooms, flooring, cabinetry, windows, and appliances also play a large role in determining the final budget. In West Hills, homeowners frequently prioritize modern layouts, energy-efficient systems, and private living spaces that complement the existing property. Permit fees, architectural planning, engineering requirements, and local zoning compliance can further affect project costs. Understanding these factors early in the planning process helps homeowners make informed decisions while reducing the likelihood of unexpected expenses during construction.