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

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.