Materials Costs for Building an ADU: What You Need to Know

  1. Costs and legal requirements for building an ADU
  2. Construction costs
  3. Material costs


Building an Accessory Dwelling Unit (ADU) on your property involves various material costs to consider. This article outlines the types of materials needed, their costs, and offers tips on planning and budgeting for your ADU project. In addition to materials, it's essential to account for labor costs, permits, fees, inspections, equipment rental, and other miscellaneous expenses.

Types of Materials for ADU Construction

The materials required for an ADU depend on its size and design. Common materials include:

  • Lumber: Lumber is typically the most expensive material, with treated wood for foundations, pressure-treated lumber for framing and sheathing, and dimensional lumber for structural components.
  • Drywall, insulation, and siding: The costs for these materials vary depending on the type and quality chosen.
  • Windows and doors: These components make up a large portion of the total material cost.
  • Plumbing fixtures and electrical wiring: Often overlooked in budgets, these materials should be considered upfront.
  • Appliances: Refrigerators, washers, and dryers can be costly, depending on the chosen type.
  • Flooring materials: These should be included when estimating material costs.
  • Foundation: Everything sits on the foundation, and it has to be right. This should be included in estimation costs.

Labor Costs and Other Expenses

Labor costs vary greatly based on the project complexity and the contractor's skill level. More experienced ADU builders may charge higher fees. In addition to materials and labor costs, consider other expenses like permits, fees, inspections, tools, and equipment rental.

Budgeting and Planning

When planning your ADU project, research material and labor costs to ensure a clear understanding of the expenses involved. Compare prices from different suppliers and buy in bulk when possible to save money. If you plan to do some work yourself, make sure to have the proper tools and safety equipment.


Understanding material costs is crucial for planning and budgeting your ADU project. Keep in mind that materials are just one aspect of the overall cost. By comparing prices from different suppliers and considering all other expenses, you can stay within budget and ensure a successful ADU construction project.

Lisa Christin
Lisa Christin

Lisa is an accessory dwelling unit expert based in Long Beach, CA. She provides tips and ADU insider information to help homeowners get started on their accessory dwelling unit projects the right way from the start.