Most lists of questions to ask a contractor have the same problem: they tell you what to ask and then leave you alone with the answer. You ask about the payment schedule, you hear something confident, and you still have no idea whether what you heard was normal, generous, or illegal.
This one is built the other way around. Each question comes with the California law, the state permit deadline, or the City of San Diego submittal requirement that lets you grade the answer on the spot. An ADU is a complete residence — kitchen, bathroom, sleeping area, its own utilities — and it is permitted like one. The rules governing it are public, specific, and checkable in an afternoon.
The ten questions, in short
| # | Ask this | A good answer sounds like |
|---|---|---|
| 1 | What is your CSLB license number and classification? | A number given without hesitation, plus “B, General Building” |
| 2 | Is this contract written as home improvement or new construction? | A direct answer, and a willingness to put it in the contract |
| 3 | What deposit are you asking for? | A figure at or below the legal cap, not a percentage of the whole job |
| 4 | How are progress payments tied to work? | Payments follow completed work, itemized by stage |
| 5 | Who prepares the full City submittal package? | The specific forms and calculations named without prompting |
| 6 | When does the City’s 60-day clock start? | On the completeness determination, not on submittal |
| 7 | Am I in the Coastal Overlay Zone, and what does that add? | A checked answer about your parcel, not a general one |
| 8 | Who handles plan-check corrections? | The contractor, at no additional charge, as a defined step |
| 9 | Which line items are allowances, and what are they set at? | Named allowances with real dollar figures |
| 10 | Who is accountable from feasibility to final inspection? | One named person, for the whole project |
The rest of this page is why each of those answers is the right one.
Start by checking the license yourself
Before the first meeting, not after. This takes about two minutes and it removes an entire category of risk that no amount of conversation can.
The Contractors State License Board publishes a free license lookup at cslb.ca.gov. Search by license number or business name and you will see the license status, the classifications held, the issue and expiration dates, the bond amount, and whether workers’ compensation coverage is on file. All of it, for any contractor in California, without asking anyone’s permission.
Ours is California General Building Contractor License #1074166. Look it up before you call us. We would rather you did.
What classification actually matters for an ADU
A detached ADU is a new dwelling, not a bathroom refresh, and the classification that covers it is Class B — General Building Contractor. The CSLB defines that classification as a contractor whose work involves structures requiring the use of at least two unrelated building trades or crafts.
There is a detail in that rule worth knowing, because it explains what a “B” license is for. A general building contractor may not count framing or carpentry toward the two unrelated trades needed to take a prime contract on a project involving other trades. In other words, the classification exists specifically to cover work that coordinates multiple trades that are not carpentry — foundation, framing, electrical, plumbing, mechanical, roofing, finishes — which is exactly what an ADU is.
A specialty license is a legitimate license. It is simply not the one written for running a whole dwelling from foundation to final inspection.
Ask: what is your license number, and what classification does it carry?
The money questions California has already answered
This is the section that changes how the conversation goes, because several of the answers are not a matter of company policy. They are set by statute.
California’s home improvement contract rules reach beyond the four walls of the house. The definition in Business and Professions Code section 7151 covers repairing, remodeling, altering, converting, modernizing or adding to residential property, and it explicitly extends to improvements of structures or land adjacent to a dwelling house — driveways, patios, garages, and the like. Where a contract falls under those rules, the following apply:
| Rule | The requirement |
|---|---|
| Written contract | Required for any home improvement project over $500 |
| Down payment cap | No more than $1,000 or 10% of the contract price, whichever is less, excluding finance charges |
| Progress payments | Payments cannot exceed the value of the work performed, apart from the down payment |
| Change orders | All changes must be executed as written change orders, signed before the work proceeds |
| Identification | The contract must carry the contractor’s license number and business address |
Read the down payment line again, because it surprises almost everyone. On a $300,000 ADU, the cap under those rules is not $30,000. It is $1,000 — because $1,000 is the lesser of the two figures. The 10% half of the rule only governs jobs under $10,000.
There is one narrow exception, and it is rare. A contractor holding a blanket performance and payment bond on file with CSLB may request the full contract amount up front. Only about two dozen companies in the state have been approved to use one, and a contractor who has that bond will be able to say so plainly and show you.
These are the statutory rules as published by the Contractors State License Board. They are not legal advice, and the treatment of a given contract depends on how that contract is written.
The question almost nobody thinks to ask
Here is the honest complication, and we would rather name it than pretend the rule is simpler than it is.
A detached ADU sits in a genuinely gray area. It is a new dwelling unit, but it is also a structure built on land adjacent to an existing dwelling house, which is language the home improvement statute uses directly. Different contractors paper these projects differently, and the deposit you are asked for will follow from that choice rather than from anything about your lot.
So ask it directly: is this agreement written as a home improvement contract or as new residential construction, and which payment rules apply to my deposit?
You are not trying to catch anyone out. You are establishing that the person across the table knows which rules govern the document they are asking you to sign. A contractor who has thought about this will answer in a sentence. One who has not will change the subject to something else, and that is information too.
The permit questions, and the clock most homeowners never hear about
State law puts real deadlines on ADU permits, and knowing them tells you a great deal about who you are talking to.
Under California’s ADU statutes, as summarized in the state HCD ADU Handbook, a permitting agency must determine whether your application is complete and give you written notice of that determination no later than 15 business days after receiving it. If it is incomplete, the agency has to provide a list of the incomplete items and explain how to fix them. Once the agency has a completed application, and there is an existing single-family or multifamily dwelling on the lot, it must approve or deny within 60 days. If an application is found incomplete or is denied, the agency must offer an appeal process and issue a final written determination no later than 60 business days after receiving the appeal.
Now notice where the leverage is. The 60-day clock runs from completeness, not from submittal. A package that goes in thin gets bounced inside 15 business days and the 60 days never starts. A contractor who submits a complete package the first time is not being meticulous for its own sake — they are starting the statutory clock weeks earlier than the alternative.
Ask: when does the 60-day clock start on my project, and what have you done to make sure it starts on the first submittal?
What a complete City of San Diego package actually contains
If you are in the City of San Diego, this is checkable. The City’s Information Bulletin 400 covers ADUs and JADUs, and it is unambiguous on the first point: a building permit is required for all ADU and JADU creation, with no exemptions. The minimum submittal for each unit includes:
- ✓A site plan and vicinity map
- ✓Floor plans, roof plans, elevations and sections
- ✓Structural plans, structural calculations and truss details
- ✓Title 24 energy calculations
- ✓Form DS-3032, the General Application
- ✓Form DS-16, the Water Meter Data Card
- ✓Form DS-560, the Storm Water Applicability Checklist
You do not need to understand every item. You need to hear your contractor name most of them without looking anything up, and tell you who prepares each one — because structural calculations and Title 24 energy calculations are produced by licensed professionals, and someone has to be paying for and coordinating that work. If the answer is vague about who produces what, you have found the gap where projects stall.
There is also a route worth asking about: applications using the City’s preapproved plans are subject to a 30-day review. Whether that path suits your lot is a real design conversation with real tradeoffs, but it should be a conversation, not an omission.
If you are anywhere near the coast
For properties in the Coastal Overlay Zone, a Coastal Development Permit is required for an ADU or JADU that is not entirely within an existing structure, that increases habitable area, or that converts non-habitable space. In non-appealable coastal areas, an administrative CDP may be issued as a building permit where specific findings are satisfied, which streamlines things considerably.
This is a parcel-level question, not a city-level one. La Jolla, Del Mar, Encinitas, Carlsbad and Oceanside all carry coastal overlay in parts, and two neighbors on the same street can sit differently. Ask whether your specific parcel is in the overlay, and expect the answer to have been looked up rather than estimated. Our ADU builders in La Jolla and ADU builders in Carlsbad pages go further into what the coastal path looks like in each.
Who fixes it when plan check comes back
Permit review usually returns corrections before it approves anything. That is normal, not a failure. What is not normal is for those corrections to become your problem.
Ask: when plan check returns corrections, who responds to them, how quickly, and is that work included in what I am paying you?
The answer you want names a person and treats it as a scheduled step in the project rather than an unexpected event. The answer to be careful with is any version of “we will deal with it if it happens,” because it will happen.
The scope questions that decide your final number
A low preliminary figure is not a low cost. It is usually a figure that has not caught up to the project yet, and there are three specific places that gap hides.
Allowances. An allowance is a placeholder, not a price. Cabinets, countertops, tile, fixtures and appliances are often carried as allowances, and if your actual selections run above them, the difference is yours. Ask which line items are allowances and what dollar figure each one is set at. A proposal that carries an unnamed “finish allowance” with no number in it cannot be compared against anything.
Exclusions. Ask for the exclusions list in writing, as its own section. Utilities are where this bites hardest on ADU projects — a new dwelling needs its own service, and whether the main panel has capacity is a site-specific question. A sewer or water lateral, a panel upgrade, or a trench across a finished driveway can be in scope or out of it, and the two versions of the proposal look nearly identical until you read that section.
Site conditions. Grade, soil, drainage and existing structures all affect what the unit costs to build where you want it. A feasibility review before contract catches most of this. Nothing catches all of it, so the question is not whether surprises are possible but whether the agreement defines, in advance, how they get priced and approved. Written change orders signed before work proceeds is the standard the statute already sets. Ask to see how that works in practice.
For a broader picture of where the money actually goes, our guide to what an ADU costs in San Diego breaks it down by scope, and the San Diego ADU permit process walks the approval path end to end.
One question about accountability
Ask who owns the project from feasibility through final inspection — and then ask the same question again about design, about permitting, and about construction.
If the name changes depending on which phase you ask about, the coordination between those phases is yours. That is a workable arrangement if you know it going in and have the time for it. It is a difficult one to discover in month four.
This is the structural difference between a design-build team and a set of separate vendors, and it is worth being plain about our own position: as ADU builders in San Diego, Eco Home Builders runs design, feasibility, selections, permitting and construction as one accountable team, and project information, schedules, photos and decisions are documented in Buildertrend so there is one place to look rather than a thread of texts. We are not going to claim that removes every variable from a construction project. It does mean one team owns the answer when something needs resolving.
Frequently asked questions
Before you sign
Three things are worth doing in the order listed. Look up the license at cslb.ca.gov. Ask which payment rules the contract is written under, and get the deposit figure in writing. Read the exclusions section before you read the price.
A proposal you can actually compare is worth more than one that is simply lower.
