Custom ADU Builder

Name: Custom ADU Builder — ADU Builder Tour
Uploaded: 2026-07-16T16:53:11.831Z
Description: Custom ADU Builder is a CSLB-verified contractor listed in Orange County with classification B.

Serving Anaheim, Huntington Beach, Costa Mesa, Fullerton & more · Based in Fullerton, CA

5.02 verified reviews

Pricing on request — unlock Custom ADU Builder's ADU pricing for your project

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About Custom ADU Builder

Custom ADU Builder is a CSLB-verified contractor listed in Orange County with classification B.

3+ years building ADUs · CSLB 1101360 · B - General Building Contractor

Custom ADU Builder ADU pricing

Pricing varies by unit type, size, finishes, and site conditions. Unlock Custom ADU Builder's project pricing for your lot — free, no obligation.

Unit type	Typical size	Pricing
Studio / JADU	≤ 500 sq ft	Pricing locked — unlock to view
1-bedroom detached ADU	600–750 sq ft	Pricing locked — unlock to view
2-bedroom detached ADU	750–1,000 sq ft	Pricing locked — unlock to view
Garage conversion	400–600 sq ft	Pricing locked — unlock to view
Attached ADU	400–800 sq ft	Pricing locked — unlock to view

Pricing is unlocked per project

Share a few details and we'll send Custom ADU Builder's pricing for your build.

Services Custom ADU Builder offers

Detached ADUs
Attached ADUs
Garage Conversions
Junior ADUs (JADU)
Permitting

What Custom ADU Builder handles

Design & permitting

In-house design and full permit handling.

Architectural design & 3D renderings
Structural & Title 24 energy plans
City plan-check submittal & corrections

Construction

Turnkey ground-up and conversion builds.

Foundation & framing
Detached, attached & garage-conversion ADUs
Electrical, plumbing & HVAC

Financing

Guidance and lender introductions.

Renovation / construction-loan guidance
HELOC & cash-out refinance referrals
ADU-specific (after-build-value) lenders

Project types

ADU formats this builder takes on.

Detached ADU
Attached ADU
Garage / ADU conversion

Warranty & support

What's covered after move-in.

Workmanship warranty
Manufacturer materials warranties
Dedicated project manager

Reviews of Custom ADU Builder

5.02 reviews

Distribution

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Verified

February 2026

I had an excellent experience working with Custom ADU Builder. From start to finish the project was smooth and professional. Dennis was incredibly responsive - always quick to reply to messages and consistently answered my phone calls which made communication easy and stress free. I appreciated how dedicated the team was . A special thank you to Sicola who worked diligently to follow up with Southern California Edison. The extra effort made a huge difference and showed their commitment to going above and beyond for their clients. I highly recommend this company to anyone looking to build an ADU.

Cecilia Lacuesta0 found this helpful

Verified

February 2025

Start to finish, Dennis and his team, were excellent! Custom ADU Builders recently completed my 860 sqft ADU in Los Angeles. The team does excellent work, is professional, and easy to work with. And at a fair price. I would not hesitate to use them again on future projects.

Courtney Chanel0 found this helpful

Frequently asked questions about Custom ADU Builder

What does Custom ADU Builder offer?

Custom ADU Builder is a full-service ADU builder serving Fullerton, CA, handling design, permitting, and turnkey construction for detached ADUs, attached ADUs, garage conversions, and junior ADUs (JADUs). Custom ADU Builder holds a 5.0-star rating across 2 verified homeowner reviews.

Is Custom ADU Builder licensed and insured?

Yes. Custom ADU Builder holds an active CSLB license (1101360), classified B - General Building Contractor, and is bonded and insured.

How much does Custom ADU Builder charge to build an ADU?

Custom ADU Builder prices every ADU per project — your cost depends on size, finishes, and site conditions. Garage conversions are the most affordable path; detached units cost more. Pricing is unlocked per project: request a quote to get Custom ADU Builder's exact, no-obligation estimate for your lot.

What areas does Custom ADU Builder serve?

Custom ADU Builder builds ADUs in Anaheim, Huntington Beach, Costa Mesa, Fullerton, Newport Beach, Rancho Cucamonga, and surrounding areas.

How long does Custom ADU Builder take to build an ADU?

Most ADU projects run 6–12 months end to end — roughly 1–2 months for design and permitting (California caps plan check at 60 days for compliant units) and 4–8 months of construction. Custom ADU Builder confirms a timeline for your specific project during the feasibility consultation.

How do I get a quote from Custom ADU Builder?

Tap any "Get a Quote" button on this page to share a few details about your property and project. We'll confirm your service area, match you directly with Custom ADU Builder, and set up your free feasibility consultation — no obligation.

Where Custom ADU Builder works

Fullerton, CAService-area map

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City Building & Safety
Planning Department
Permit Center