5 Mistakes to Avoid With ADU Builders

5 Mistakes to Avoid With ADU Builders

Most ADU projects that go over budget don’t blow up during framing. They blow up because the homeowner signed a contract without a fixed price, and the builder treated every soil condition and inspection revision as a change order. In Los Angeles, where an accessory dwelling unit (a second home on your existing lot, often called a granny flat or backyard home) can run from $180,000 to over $400,000 depending on size and site conditions, those surprises add up fast. Here are the five mistakes we tell every homeowner to avoid before they sign anything.

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Mistake 1: Signing a Cost-Plus Contract Instead of a Fixed-Price Contract

A cost-plus contract means you pay the builder’s actual costs plus a markup, usually 10% to 20%. If lumber spikes, you pay more. If the crew hits rock when digging the foundation, you pay more. If the project takes longer than expected, you pay for more labor weeks. The builder has almost no incentive to control costs because every extra dollar they spend earns them a percentage.

A fixed-price contract locks the total before work starts. The builder absorbs the risk of material fluctuations and site surprises because they priced those contingencies up front. In our experience across Los Angeles neighborhoods like North Hollywood, Van Nuys, and the San Fernando Valley, the difference between these two contract types is often $40,000 to $80,000 on a detached ADU.

What to ask:

• Is this price fixed, or will it adjust as actual costs come in?
• What site conditions are excluded from the price?
• If you find something unexpected during excavation, who pays for that?

At Lodgewick ADU Builders home, every project starts with a written price before any work begins. Not an estimate, not a range. A price. If it’s not fixed, walk.

Mistake 2: Letting the Builder Pull Permits Under Your Name as Owner-Builder

There is a corner of the Los Angeles ADU industry that suggests a homeowner act as “owner-builder” to save money on permitting. What they don’t tell you is that as owner-builder, the legal responsibility for code compliance, worker injuries, and construction defects lands directly on you. If a worker gets hurt on your property and the builder’s insurance doesn’t cover the claim because they’re not the permit holder, you’re financially exposed.

A licensed ADU contractor pulls permits under their own contractor license. That means their bond, their insurance, and their license are on the line if something goes wrong. The Los Angeles Department of Building and Safety (LADBS) tracks permit histories, and inspectors look at who signed the permit application. That signature matters when a plan check comes back with three rounds of corrections.

Ask your builder directly: “Will you pull the permit under your contractor license, and can I see your license number before we sign?” If they hesitate, that’s your answer.

Mistake 3: Signing Without a Written Construction Schedule with Milestone Dates

Every month I hear from an LA homeowner whose ADU is “almost done” for the fourth time. The drywall has been staged in the driveway for six weeks. The inspector was supposed to come last Tuesday. These projects don’t drag because of bad luck. They drag because there was never a written schedule with consequences attached.

A real construction schedule includes milestone dates: demolition complete, foundation poured, framing passed inspection, rough electrical/plumbing signed off, drywall closed, final inspection scheduled. Each milestone has a projected date. A good builder communicates about schedule shifts in writing, with a revised date attached.

In Los Angeles, a typical garage conversion takes 4 to 6 months from permit issuance to final. A detached new-build ADU runs 7 to 11 months. If a builder tells you they can finish a ground-up ADU in 90 days, ask them to show you the schedule and the last three projects that hit that timeline. We pulled one out of a garage over in Eagle Rock last spring where the previous contractor had been “finishing up” for nine months. There was no schedule. There was no leverage. Just a hole in the roof.

Mistake 4: Choosing an ADU Builder Based on Renderings Rather Than Permitted, Finaled Projects

Renderings are beautiful. They’re also cheap to produce, and some ADU companies in Los Angeles invest more in their 3D marketing images than in their actual construction crews. A rendering shows you what a perfect project could look like. It does not show you whether the builder’s work passed LADBS inspection, whether the finaled project matches the permitted plans, or whether the homeowner got a certificate of occupancy.

Before you hire anyone, ask for a portfolio of permitted, finaled projects. “Finaled” means the city has closed out the permit file and issued the final sign-off. A project that was built without a final is a liability, not a reference. Then ask to speak with two or three past clients. Ask them: Did the price change? Did the builder show up when they said they would? Would you hire them again?

If a builder shows you only renderings and “concept work,” keep looking. If they hesitate to connect you with past clients, keep looking faster.

Mistake 5: Failing to Confirm in Writing What the Warranty Covers

Every ADU builder says they stand behind their work. Very few put it in writing with specifics. A verbal warranty is worth exactly the paper it’s not printed on. What you need is a written guarantee that states:

• What’s covered: structural framing, roofing, drywall, windows, doors, electrical, plumbing, HVAC, finish work
• For how long: one year is common, but some issues like roof leaks or foundation settling may need longer coverage
• Response time: if you file a warranty claim, how quickly does the builder show up to assess it
• What’s excluded: normal wear and tear, homeowner-caused damage, third-party appliances

At Lodgewick ADU Builders, our 365-Day Done Right Promise covers all of this in writing, delivered before work begins. If the work isn’t right within that year, we come back and make it right. Free return visit. That’s the whole point of The Kingswell Way: say the price before the work, show up in the window you’re given, leave the job site cleaner than you found it, put the guarantee in writing, come back if it fails.

In Los Angeles, where a permitted ADU adds real rental income and resale value, the builder’s warranty should be a written contract term, not a handshake. If it’s not in writing, assume it doesn’t exist.

When to Call a Pro

If you’re reading this and realizing you can’t answer all five of these questions about your current builder, that’s not a sign you’re being difficult. It’s a sign you’re paying attention. ADU construction involves structural engineering, LADBS plan checks, foundation work, electrical service runs, and a dozen other disciplines where a mistake costs five figures to fix. You don’t need to become an expert. You need a builder who has already done it right, repeatedly, with paperwork to prove it.

If you’re in Los Angeles and want help thinking through any of this, call us at (254) 602-5618. We’ll walk through your lot, your budget, and your timeline. No pressure, no change orders at the door, just straight answers.

Related: ADU Builders in Los Angeles | Garage Conversion Contractor in Los Angeles | Home Addition Contractor in Los Angeles

The Bottom Line

Five mistakes, all of them preventable, all of them expensive when left unchecked:

1. Cost-plus contracts shift every dollar of risk to you. Fixed price or walk.
2. Owner-builder permits put your finances on the hook for someone else’s work.
3. No written schedule means no leverage when the project crawls past month 10.
4. Renderings prove nothing. Permitted, finaled projects with LADBS sign-off prove everything.
5. A verbal warranty isn’t a warranty. Demand it in writing, with coverage and response time spelled out.

Building an ADU is one of the smartest investments an Los Angeles homeowner can make. It’s also one of the easiest ways to lose serious money if you hire the wrong builder. Ask the hard questions up front. Get everything in writing. If the builder balks at any of it, that’s information, and you should use it.

If you’re in Los Angeles and need help, Lodgewick ADU Builders offers free estimates. Call (254) 602-5618 and we’ll have a conversation about what makes sense for your lot, your budget, and your timeline.

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