5 Questions Before Hiring an ADU Contractor

Building an Accessory Dwelling Unit (ADU) is no longer just a trend; it is a major real estate investment and a lifestyle shift. Whether you are creating a rental property, building a home office, or preparing for family to move in, the contractor you choose will dictate whether the process is a smooth transition or a stressful nightmare.

Before you sign a contract or hand over a deposit, you need to conduct a serious interview. Here are the five critical questions you must ask your potential ADU contractor.

1. "How well do you know the 2026 California ADU legislation (like SB 543)?"

California state law is highly favorable to ADU development, but the rules just shifted significantly in 2026. A contractor who is operating on outdated knowledge can cost you thousands of dollars or months of delays.

What to listen for:

They should know that local agencies now have a strict 15-business-day timeline to determine if your application is complete, and a 60-day maximum to approve or deny.
They should understand the "interior livable space" definitions.
They should proactively mention that keeping an ADU at or below 750 square feet makes it exempt from state development impact fees—a massive cost-saving strategy.

2. "How do you handle extensive site preparation and existing structures?"

In Southern California, very few of us have perfectly flat, empty backyards ready for a foundation. Creating the footprint for an ADU often involves significant pre-construction logistics.

What to listen for: You want a contractor who isn't intimidated by complex lot clearing. For example, if your plan involves navigating the permits to demolish an in-ground swimming pool to make room for the new unit, your builder needs to explain exactly how they coordinate that demolition, manage the soil compaction, and schedule the inspections before the ADU foundation is even poured. Ask them to walk you through a timeline that includes this heavy site prep.

3. "What is your approach to Universal Design and multi-generational living?"

If the goal of the ADU is to house aging parents or create a long-term, multi-generational living arrangement, standard builder-grade finishes won't cut it. The space needs to be functional for someone with mobility limitations without feeling clinical.

What to listen for: A forward-thinking contractor should be enthusiastic about "aging-in-place" concepts. They should suggest:

Zero-step entries and wider doorways (36 inches minimum) for wheelchair or walker accessibility.
Curbless showers with reinforced blocking behind the walls for future grab bars.
Smart home integration: Ask about their experience incorporating foundational tech that allows for voice-activated lighting, climate control, or emergency response systems to give older adults more independence.

4. "Are utility upgrades included in this bid, specifically the electrical panel?"

This is the number one "hidden cost" that surprises homeowners. A luxury ADU with a full kitchen, its own HVAC system, and modern appliances draws a lot of power.

What to listen for: A trustworthy contractor will evaluate your existing main electrical panel during the site visit. In 2026, most homes require a heavy-up or a dedicated subpanel (which can run anywhere from $15,000 to $40,000 depending on the property). Ensure they specify whether trenching, independent metering, and panel upgrades are baked into the contract price or if those will be billed as change orders later. Independent metering is crucial if you ever plan to rent the unit out or sell it separately.

5. "What is your payment schedule, and do you provide unconditional lien releases?"

Never hire a contractor who asks for 50% of the project cost upfront. In California, state law dictates that a contractor cannot ask for a down payment of more than 10% of the total project cost or $1,000, whichever is less.