How to Compare ADU Quotes, Line by Line

The worksheet

The 13-line ADU bid comparison sheet

Fill one column per builder. Write the figure or the words the bid actually uses. If the bid is silent on a line, write "not stated" — and ask.

When the sheet is full, the real comparison is usually obvious. The "cheap" bid is often the one with three blank lines.

Lines 1–2

First, make sure everyone priced the same building

The most common reason two bids differ is that they describe different projects. One builder priced a 600 sq ft one-bedroom; another heard "ADU" and priced a studio. One assumed a slab; another assumed a raised floor on a slope.

What to do. Write the project down once, in a paragraph, and send the same paragraph to every builder: the ADU type (detached, attached, garage conversion, junior ADU, basement conversion), the size, the number of storeys, bedrooms and bathrooms, the finish level, and what you know about the lot. If you have drawings, every builder bids the same set.

This is what the brief from our lot checker is for: one written description of your lot and project that every builder can price against, so the bids come back comparable.

The test. Read line 1 across the row. If the three descriptions would not produce the same building, stop — you are not ready to compare prices yet.

Lines 3–7

Then split the money into the same buckets

A single lump sum cannot be compared with anything. Ask for the price in separate parts, and put each part on its own line.

Line 3 — Construction price

The building itself: foundation, framing, roof, exterior, insulation, plumbing, electrical, kitchen, bathroom, finishes. Ask whether it is a fixed price or an estimate, and what would change it.

Line 4 — Design, engineering and permit drawings

Architectural plans, structural engineering, energy calculations, surveys, and any report your lot needs. Some builders include all of it. Some assume you arrive with stamped drawings. Neither is wrong — but one bid includes tens of hours of professional work and the other does not.

Line 5 — Site work and utilities

Grading, drainage, retaining walls, trenching, and the water, sewer, gas and electrical runs to the unit — including a panel upgrade if the house needs one. On a flat lot with services nearby this line is modest. On a slope, on septic, or with a long run from the street, it can decide the project. A bid that says "site work by owner" or "utilities excluded" has left out the least predictable cost on the sheet.

Line 6 — Fees

Plan check, building permit, impact fees, school fees, utility connection charges. Ask one question: are fees inside your number, or do I pay them directly on top? Either answer is fine. Not knowing is not.

Line 7 — Allowances and exclusions

An allowance is a placeholder — "$X for cabinets" — that becomes a change order when the real thing costs more. An exclusion is something the builder is telling you they are not doing. Read both lists side by side. Ask each builder to price the items the others included.

The test. Add lines 3 to 6 for each bid, then read line 7. Only now do you have totals worth comparing.

Lines 8–9

Schedule and payments: the terms that protect you mid-project

Line 8 — Schedule

Ask for two dates and one condition: the start date, the date of final inspection, and what the start depends on (permit issued, drawings approved, a deposit). A builder who gives a duration but no start date has told you nothing about when you will have a finished unit.

Ask, too, how many ADUs the builder has finished in your town and for the permit numbers. Permit records are public; you can check how long those projects took.

Line 9 — Payment schedule

Payments should follow finished work — foundation complete, framing complete, rough inspections passed — not calendar dates. California law caps the down payment on a home-improvement contract. The Contractors State License Board publishes the current cap, and its guidance on progress payments, at cslb.ca.gov; check it before you are asked for a deposit.

The test. If you stopped the project after any payment, would the work in place be worth roughly what you had paid? If a schedule fails that test, ask for it to be re-staged.

Lines 10–13

Licence, insurance, warranty and the fine print about your lot

Line 10 — The licence

Every bid should carry a CSLB licence number. Look it up yourself at cslb.ca.gov. Check that the licence is active, that the name matches the contract, that the classification covers the work, and whether any complaints or disciplinary actions are disclosed. It takes five minutes and it is the cheapest due diligence on the sheet. Our fuller walk-through: how to vet an ADU builder.

Line 11 — Insurance

Two policies: general liability, and workers' compensation. The CSLB record shows whether workers' compensation is on file or whether the contractor has declared no employees — which matters if a crew turns up. Ask for a certificate of insurance naming you.

Line 12 — Warranty

What is covered, for how long, and who you call. A written warranty on workmanship is separate from the manufacturers' warranties on the products.

Line 13 — Conditions the lot must clear

Most bids are conditional: "subject to soils report," "assumes existing sewer lateral is adequate," "assumes no design review." These are not small print. Each one is a point where the price can move after you have signed. List them, and ask what each would cost if it went the wrong way.

Our lot checker flags the common ones for your address — slope, septic, fire zone, coastal zone, design review, and in San Francisco the tenant and rent-control questions — so you can raise them before the bid, not after.

Reading the result

Seven signs a bid is not ready to sign

1. A single lump sum with no breakdown.
2. Line 5 blank — site work and utilities "to be determined."
3. Fees unmentioned.
4. Allowances for most of the finishes, so the real price is unknown.
5. A deposit request before a written contract, or a large first payment before any work.
6. A promised permit date. Nobody controls the permit office.
7. Pressure to sign today. A real price holds long enough for you to check a licence.

And three signs of a good one: it answers every line without being asked twice; it tells you what it excludes; and the builder is willing to see the other bids' scope and price the difference.

Before you ask for quotes

What makes a builder take your request seriously

A builder can only price what you can describe. Owners who arrive with the six items below get bids that can be compared; owners who do not get guesses. Have these in hand:

• The address and jurisdiction — city, or unincorporated county.
• What you want to build, in one paragraph (line 1 of the sheet).
• What it is for — family, rental, or resale value — because it changes the design.
• Your budget range and how it is funded. A builder cannot design to a number you will not say.
• Your timing. "Ready to start design now" and "sometime in the next two years" are different conversations.
• What you already know about the lot — slope, septic, fire zone, tenants.

The lot checker asks exactly these questions and puts the answers on one page with this 13-line sheet attached.

Where we stand, plainly. ADU Build Works plans to introduce owners to at most three licensed builders per territory. As of November 2026 no builder is signed to our roster, so we cannot get you quotes today. The sheet above is free to use with any builder you find yourself.

Questions, answered

Comparing ADU bids: quick answers

Keep going

Related guides

Check your lot

Get the brief that every builder can price

Type your address and tap twice. You get a plain-language verdict on screen, then a one-page brief with this comparison sheet attached — print it or save it. We ask for contact details only if you choose to save your brief. No builders are signed to our roster yet, so no quotes are available today and no builder will contact you.