What to Expect During the ADU Construction Process
Adding an accessory dwelling unit (ADU) to your property is a major investment that enhances both functionality and value. Whether you’re building for family, rental income, or personal space, understanding the construction process helps you prepare for each stage. At MF ADU, we guide homeowners through every phase to ensure their project runs smoothly, efficiently, and on schedule.
Step 1: Site Preparation
Every successful ADU project begins with proper site preparation. This includes surveying your lot, clearing space, and ensuring access for construction. We handle grading, foundation planning, and utility connections before any building begins. For prefabricated ADUs, this step happens while your unit is being built off-site—saving time and reducing disruption.
Step 2: Foundation and Utility Installation
Once the site is ready, we install the foundation. Depending on your design, this could be a concrete slab or pier system. Our team also connects essential utilities such as plumbing, electrical, and water lines to ensure everything is ready for installation once the ADU arrives.
Step 3: Off-Site Fabrication (for Prefab ADUs)
While site preparation takes place, the prefabricated ADU is built in a controlled factory environment. Each component—from the frame to insulation and finishes—is constructed with precision and inspected for quality. This step eliminates delays caused by weather and ensures a consistent, high-quality build.
Step 4: Delivery and On-Site Assembly
When the ADU is complete, it’s transported to your property. Our team assembles the unit quickly, aligning each component with the foundation and connecting all systems. This phase usually takes just a few days, compared to several weeks for traditional construction.
Step 5: Finishing Touches and Inspections
After assembly, we add final details such as flooring, paint, fixtures, and landscaping. The ADU then undergoes a series of inspections to confirm it meets California’s safety and energy standards. Once approved, your new space is move-in ready.
Did you know?
Did you know? Prefabricated ADUs typically require 40–60% less on-site construction time than traditional builds—reducing noise, disruption, and neighborhood impact.
Building with Confidence
Understanding what to expect during the ADU construction process helps you plan ahead and stay confident throughout the journey. At MF ADU, we manage every stage—from design to final inspection—so you can enjoy a seamless experience and a high-quality finished home.
See our prefabricated ADU models to learn how we make construction simple and stress-free.
Frequently Asked Questions
How long does the ADU construction process take?
Timelines vary, but most projects are completed within a few months from permits to installation.
Will construction disrupt my daily life?
Not much. Prefabricated ADUs minimize on-site noise and activity compared to traditional construction.
Do I need to be home during construction?
No. Our team coordinates all site work and inspections, keeping you updated throughout the process.
What happens if there are delays?
Prefab construction reduces most delays, but we communicate any schedule changes in advance.
How do final inspections work?
Once construction is complete, city inspectors verify the ADU meets local and state building requirements.