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Part 3: What Should an ADU Really Cost in My Area?

June 18, 2025
This beautiful home addition of approx. 650 square feet was a way to bring this family's child closer to home as they go through school. Complete with a bedroom, en suite bathroom, small kitchen, and

This is the third article in Pinnacle Design and Build's 10-part guide for homeowners planning ADUs

and full remodels. In this article, we break down the most common questions we hear: How much

does an ADU really cost? What drives the price up (or down)? And how can you plan ahead to stay

on budget?

1. National vs. Local Averages

The national average for a new ADU is between $150,000-$250,000, but in Los Angeles and most

of Southern California, ADU costs typically range from $90,000 for a garage conversion to

$300,000+ for a new, detached unit. At Pinnacle Design and Build, we help our clients navigate

these ranges by understanding their lot, goals, and local permitting costs.

2. What Factors Affect ADU Cost?

Site conditions, utilities, soil grading, access to plumbing and electrical, the type of ADU (garage

conversion vs. detached), finishes, permits, and design complexity all play a huge role in your final

ADU cost.

3. Garage Conversions: Most Affordable ADUs

Garage ADUs tend to fall in the $90,000-$170,000 range. This includes basic finishes, permits, and

essential upgrades. Costs increase if foundation repair, utility trenching, or structural reinforcement

is needed.

4. Detached ADUs: Higher Cost, Greater Flexibility

Detached ADUs offer privacy and rental potential, but come with a higher price tag. Budget

$200,000-$300,000+ depending on size, access, finishes, and city fees. Pinnacle Design and Build

provides clients with detailed estimates so there are no surprises later.

5. How to Get an Accurate ADU Estimate

The best way to understand your ADU cost is to get a site-specific estimate. Factors like

topography, existing structures, and local zoning rules can dramatically shift pricing. We recommend

working with a design-build firm (like Pinnacle Design and Build!) to walk the site and develop a real

budget.

6. Financing Your ADU

ADU financing options include home equity lines of credit (HELOCs), renovation loans, and private

lenders. Some cities also offer grants or permit fee waivers. We help homeowners explore every

path to make their ADU cost manageable.


Want a personalized ADU cost estimate? Contact Pinnacle Design and Build today for a free

consultation. We'll walk your property, explore your goals, and give you an honest, detailed

estimate - no sales pressure, just answers.

Contact Us Today