ADU Builder in Riverside, CA

Backyard cottages, garage conversions, attached suites — code-compliant, integrated with your home, built so the rental income (or family it houses) starts the day we hand you the keys.

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What is an ADU?

An Accessory Dwelling Unit (ADU) is the most flexible square footage you can add to your property. Rental income, multigenerational living, a home office that's actually separate from the house, a guest suite that doesn't take over your spare bedroom — same building, different use cases. California's permitting reforms have made ADUs faster to get approved than ever, but the design, the build, and the integration with your existing home still need an experienced builder. That's where we come in.

Why Riverside homeowners build their ADU with us

ADUs sit at the intersection of three things most contractors don't handle well: tight site constraints (you're building in your own backyard), California-specific permit rules that change frequently, and the need to match the new structure to the existing home so it doesn't tank your curb appeal or your resale value. We've built ADUs across Riverside, Rancho Cucamonga, and the Inland Empire for 18 years. We know the cities' permit workflows, we work with pre-approved plans where they make sense (faster permits, lower design costs), and we build the new unit to the same standards as the main house — same roof pitch, same materials, same trim, same finish quality.

customed modern patio

What you get when we build your ADU

A unit that fits your lot — and your goals. Detached cottage (400–1,200 sq ft), attached suite (sharing one wall with your house), garage conversion (with all the structural and code upgrades that requires), or over-garage suite with a private entry.
Permits handled end to end. Plans, submittals, plan-check responses, inspections, certificate of occupancy.
Pricing in writing. Most ADUs in our area land between $150,000 and $300,000+, scoped to size, design, site conditions, and finishes. We'll narrow that range for your specific project before contract.
A schedule that respects your timeline. Most ADUs finish in 6–9 months from permit to keys.
Built to match your home. Roof pitch, siding, trim, windows, paint — all coordinated so the ADU looks like it was part of the original design.

How We Work

At JJ. Builders, our Riverside design and build process for ADUs is refined to be seamless and enjoyable. Here's how we work:

01

Discovery Call (15 minutes)

What you want the ADU for, what your property is like, what your timeline is. Free, no pressure.

02

Lot Feasibility & Design Path

We visit your property. Setbacks, utility access, slope, existing structures, and lot coverage rules all reviewed. We'll tell you what size ADU your lot can support, whether a pre-approved plan makes sense, and whether the unit should be detached, attached, or a garage conversion.

03

Design & Permits

Plans, structural engineering, energy compliance, and submission to the city. Pre-approved plans typically permit in 4–8 weeks; custom designs typically permit in 8–16 weeks depending on city.

04

Build

Foundation, framing, mechanical/electrical/plumbing, finishes. Most ADUs take 6–9 months from groundbreak. You get weekly site walkthroughs, daily updates through Houzz Pro, and one point of contact.

05

Handover & Warranty

Final inspections, certificate of occupancy, professional cleanup, and a written workmanship warranty (2 years standard, 5 years luxury tier).

What your ADU can do for you

For rental income. A well-designed long-term ADU in Riverside or Rancho Cucamonga can generate $1,800–$3,000+/month in rent depending on size, finishes, and location. Many homeowners refinance the project costs against that rental income.

For family. Aging parents, adult kids, multigenerational living. A private entry, full kitchen, and separate utilities mean it’s actually independent living — not just a finished basement with a door.

For work and life. A detached office that’s actually separate from the house. A creative studio. A guest suite that doesn’t take over your spare bedroom. Same square footage, depending on how you want to use it.

Designed to add value, not subtract from it. A well-integrated ADU adds resale value because the next buyer sees the same flexibility you did. A bolted-on ADU that doesn’t match the house subtracts value — and that’s a contractor problem, not a property problem.

Thinking about an ADU? Let's see if your lot qualifies.

The first question is always: what can you actually build on your property? Setbacks, lot coverage, utility access, and city rules all factor in. We'll talk through your goals, look at your property, and tell you whether an ADU makes sense — and if so, what type, what size, and what it'll roughly cost.

Schedule Your Discovery Call