The Cost Breakdown of Building an ADU: What to Expect
Building an accessory dwelling unit (ADU) is an exciting investment, but knowing where your money goes is key to making informed decisions. ADU costs vary based on size, design, site conditions, and construction method. At MF ADU, we believe transparency matters, so homeowners can plan confidently and align their project with their financial goals.
Design and Planning Costs
The first costs typically come from design and planning. This includes architectural drawings, engineering, and site evaluation. These steps ensure your ADU meets local requirements and fits your property correctly.
Good planning helps prevent costly changes later in the project.
Permitting and City Fees
Permits and city fees are required before construction can begin. These costs vary by city and may include building permits, plan checks, and inspection fees.
While these expenses are unavoidable, having accurate plans and experienced guidance can help prevent delays and resubmissions that add extra cost.
Construction and Installation
Construction is the largest portion of an ADU budget. This includes labor, materials, structural components, and installation.
Prefabricated ADUs often reduce construction costs because:
Most work is completed in a controlled factory environment
Material waste is minimized
Labor time on-site is reduced
These efficiencies help keep overall costs more predictable.
Utility Connections and Site Work
Utility connections can significantly impact total cost depending on your property. This may include water, sewer, electrical, or gas upgrades, along with grading and foundation work.
Early site evaluation helps identify these requirements and avoid unexpected expenses.
Interior Finishes and Final Details
Finishes such as flooring, cabinetry, fixtures, appliances, and lighting complete your ADU. Custom upgrades can increase costs, while standard finishes help keep budgets in check.
Choosing durable, low-maintenance finishes can also reduce long-term operating expenses.
Did you know?
Did you know? Prefabricated ADUs often have fewer cost overruns because pricing is established early and less affected by on-site delays or material shortages.
Plan with Confidence Using MF ADU
Knowing the cost breakdown allows you to plan realistically and prioritize what matters most. At MF ADU, we help homeowners understand each cost component and choose solutions that balance quality, efficiency, and value.
For a clearer idea of pricing ranges and options, explore our ADU pricing information.
Frequently Asked Questions
What is the biggest cost in building an ADU?
Construction and installation typically account for the largest portion of the total cost.
Do prefabricated ADUs cost less than traditional builds?
Often yes. Prefab ADUs reduce labor time and material waste, helping control costs.
Are permits included in the total ADU cost?
Permits and city fees are usually separate and vary by location.
Can I control costs by choosing simpler designs?
Yes. Smaller layouts and standard finishes help keep costs manageable.
Does MF ADU provide cost estimates upfront?
Yes. We provide clear pricing guidance early so homeowners can plan with confidence.