To compare ADU quotes, check what each one covers before you compare totals. Mark site work, trench distance, panel upgrades, fees, allowances, and payment terms as priced, excluded, or missing, then get written prices for the gaps. In Temecula, an ADU over 500 square feet can owe school fees even if it's under 750.
TL;DR
- Most of the gap between two ADU quotes comes from site work and fees, and rarely from the building.
- ADUs of 750 square feet or less skip city impact fees, but school fees can apply above 500 square feet.
- Temecula Valley Unified charges $5.38 per square foot on ADUs over 500 square feet, as of June 16, 2026.
- Check six lines in every quote: soils and grading, trench distance, electrical panel, fees, allowances, and payment schedule.
- Mark each line as priced, excluded, or missing, and get written prices for the gaps before comparing totals.
- A down payment over $1,000 is a red flag unless the contractor has a CSLB-approved bond or joint control.
- Check every contractor's license on CSLB before you sign.
One liner: Compare what each ADU quote covers first, then compare the totals.
You asked two contractors to price an ADU for your lot, and the numbers came back far apart. Before you pick the lower one, it pays to know how to compare ADU quotes line by line. The checklist below is for homeowners in Temecula, Murrieta, Menifee, Wildomar, and Lake Elsinore who have two or more bids in hand. It covers the site costs and fees quotes leave out, the questions to ask each contractor, and the red flags to catch before you sign.
Why Two ADU Quotes for the Same Lot Rarely Match
In short: Most of the gap between two ADU quotes comes from site work and fees that one quote counts and the other leaves out.
When two bids for the same plan land far apart, the building is rarely the reason [1]. Our 749 square foot two bedroom plan runs roughly $290,000, covering construction, plans, engineering, typical utilities, and standard finishes [1]. Permit fees and a site plan come on top, and school fees can too [1]. Depending on your lot, so can:
- A soils report and grading
- Long utility trenching
- Retaining walls
- New utility connection fees
Picture two quotes for that plan. One lists the soils report, the trench run, and a panel upgrade as separate lines. The other shows one number and a note that site work is excluded. It looks lower until you price what it left out. Fees are the easiest place to miss this.
School Fees Start at 500 Square Feet, Not 750
In short: An ADU of 750 square feet or less skips city impact fees. School fees can still apply once it tops 500 square feet.
ADUs of 750 square feet or less skip city impact fees, but that rule doesn't reach school fees [2][3]. Under SB 543 (2025), the school fee exemption only covers a unit that "contains less than 500 square feet of interior livable space" [2]. In Temecula Valley Unified School District, ADUs over 500 square feet pay $5.38 per square foot as of June 16, 2026 [3].
| ADU size | City impact fees | TVUSD school fees |
|---|---|---|
| 500 sq ft or less | None | None |
| 501 to 750 sq ft | None | $5.38 per sq ft |
| Over 750 sq ft | Proportionate to the main house | $5.38 per sq ft |
Take two quotes for a 749 square foot unit, where one includes a school fee line of about $4,030. The other says no fees apply because the unit is under 750 square feet. It looks $4,030 cheaper until that fee comes due. At 499 square feet, the line drops to zero.
Even an exempt unit needs TVUSD's exemption application, so ask each contractor who files it [3]. Outside TVUSD, check the district that serves your address.
The ADU Bid Comparison Checklist
In short: Check six lines in each quote: site work, trench distance, the electrical panel, fees, allowances, and the payment schedule.
Work through these steps with both quotes open, and mark each line as priced, excluded, or missing. Start by confirming both include plans and engineering. For a new detached unit, also check for solar panels, which California's 2025 Energy Code requires unless an exception applies [10].
1. Check Whether Soils and Grading Are Priced
A sloped pad can bring a soils report, engineered foundation work, retaining walls, and a drainage plan [1]. Around Lake Elsinore and Crowne Hill, slope is the biggest swing in the budget [1]. Look for each item as a priced line or a named exclusion. If none appear, you're guessing.
2. Find the Trench Distance Each Quote Assumed
Every foot between the house and the unit is trench for water, sewer, and electrical [1]. A unit 150 feet out costs far more to plumb and wire than one 20 feet away [1]. Rock or decomposed granite raises the cost per foot [1]. Each quote should state its distance. On septic lots in Wildomar and Wine Country, see whether the quote covers the county's septic review [1].
3. Confirm Someone Checked Your Electrical Panel
Older homes on 100 or 125 amp service usually need a panel upgrade to carry a second dwelling [1]. It's a known, quotable cost once someone looks. A quote that never mentions your panel either assumed it's fine or didn't check.
4. Line Up Permit, School, and Connection Fees
Write down which fees each quote includes, excludes, or skips. School fees follow the 500 square foot line covered above [3]. A garage conversion inside existing space can't be charged a new utility connection fee [2]. A new detached unit can, if the fee is proportionate to its size or plumbing fixtures [2].
5. Turn Allowances Into Real Numbers
An allowance is a placeholder amount for items you haven't picked yet, like flooring or fixtures. A low allowance makes a quote look cheaper, and you cover the difference once you choose. Compare allowance amounts, or ask for fixed prices on your finishes, plus the brand and model on big items like windows and fixtures. Our prices include standard finishes and show premium upgrades as their own line [1].
6. Match Payments to Finished Work
On an ADU contract in California, payments after the down payment can't exceed the value of work done or materials delivered [4]. A payment schedule has to show each payment amount and the work it covers [5]. Contractors with a CSLB-approved performance and payment bond or joint control are exempt from both rules [7]. Line up each quote's schedule by phase. If a payment comes due before its phase of work is done, ask why.
Lay Two ADU Builder Quotes Side by Side
In short: Compare totals only after both quotes price the same lines.
First, make sure both quotes are the same kind of number, since a range from a first visit won't line up against a fixed written scope. Mark each line in each quote as priced (a dollar amount), excluded (named but not priced), or missing (never mentioned). Here's an example for the same 749 square foot unit.
| Checklist line | Quote A | Quote B |
|---|---|---|
| Plans and engineering | Included | Missing |
| Solar (new detached unit) | Priced | Missing |
| Soils and grading | Priced | Excluded |
| Trench distance | Priced, distance stated | Excluded |
| Electrical panel | Upgrade priced | Missing |
| Permit fees | Excluded | Excluded |
| School fees | About $4,030 [3] | Listed as not applicable |
| Connection fees | Priced | Missing |
| Allowances | Fixed prices | Allowance amounts |
| Payment schedule | Tied to phases | Not listed |
Quote B isn't the lower bid until its blanks are filled, so ask that contractor for a written price on every excluded or missing line. Add those in, then compare totals.
Five Questions to Ask an ADU Contractor About a Quote
In short: Ask how each contractor built their number, and get the answers in writing.
The checklist shows what's on the page, and these questions show what each contractor assumed to get there.
- Did you walk the lot before writing this number? Site costs depend on your lot, so a clear answer names what they measured, like trench distance and slope [1].
- What interior livable space did you use for school fees? The exemption uses interior livable space, so two size figures can fall on opposite sides of 500 square feet [2].
- Are permit fees in this price? If not, get that number before comparing totals.
- What happens to the price if the soils report finds a problem? A good answer covers how extra work gets priced and approved first.
- What did you assume for allowances? One set below the finishes you want turns into a bill later.
Get each answer in writing and add it to your table.
ADU Contractor Red Flags to Catch Before You Sign
In short: A license that doesn't check out, an oversized deposit, a lump sum bid, or a same-day deadline should stop your signature.
- The license doesn't check out. Run each contractor's license number through CSLB's Check a License tool, and confirm the status is active and the business name matches the quote [6].
- The down payment tops $1,000. You may see 10% at signing called fair. California caps a down payment at $1,000 or 10% of the contract, whichever is less, and CSLB names ADU construction in that rule [4][7]. On any contract over $10,000, that cap works out to $1,000. The exception is a contractor with a CSLB-approved bond or joint control covering the full job, so ask to see it [7].
- The bid is one lump sum. A single number gives you nothing to run through the checklist, so ask for line items before you compare.
- The price only holds if you sign today. A same-day deadline leaves no time to compare quotes or check a license, so ask for the expiration date in writing.
ADU Quote FAQs
In short: Quick answers on fees, payments, licenses, solar, and what to check in each ADU quote.
How do I compare two ADU quotes?
Compare what each quote covers before you compare totals. Mark every line as priced, excluded, or missing.
Do ADUs under 750 square feet pay school fees in Temecula?
They can. The 750 square foot rule covers city impact fees, while the school fee exemption only covers ADUs with less than 500 square feet of interior livable space.
How much are school fees on a 749 square foot ADU in Temecula?
About $4,030 at Temecula Valley Unified's rate of $5.38 per square foot, effective June 16, 2026.
Does an ADU that owes no school fees still need district paperwork?
Yes. Temecula Valley Unified requires an exemption application even when the fee is $0.
Do garage conversion ADUs pay utility connection fees?
A garage conversion inside existing space can't be required to add a new utility connection or pay a related connection fee.
Do ADUs over 750 square feet pay city impact fees?
They can. Impact fees on an ADU over 750 square feet are charged in proportion to the size of the main house.
How much can an ADU contractor take as a down payment in California?
$1,000 or 10% of the contract price, whichever is less. Contractors with a CSLB-approved bond or joint control covering the full job are exempt.
Can an ADU contractor charge ahead of the work?
Only if they have a CSLB-approved bond or joint control covering the full job. Otherwise, payments after the down payment can't exceed the value of work done or materials delivered.
How do I check an ADU contractor's license?
Search the license number on CSLB's Check a License tool.
What is an allowance in an ADU quote?
An allowance is a placeholder amount for items you haven't picked yet, like flooring or fixtures.
Why does trench distance change an ADU quote?
Every foot between the house and the unit is trench for water, sewer, and electrical.
Will my ADU need an electrical panel upgrade?
Older homes on 100 or 125 amp service usually need one to carry a second dwelling.
Why does a soils report matter when comparing ADU quotes?
On a sloped lot, a soils report can come with engineered foundation work, retaining walls, and a drainage plan.
What should I ask an ADU contractor about their quote?
Ask whether they walked the lot, what size they used for school fees, whether permit fees are included, how extra work gets priced, and what they assumed for allowances.
Should I pick the lowest ADU quote?
Not until both quotes cover the same lines. A lower total that leaves out site work or fees can end up higher once those lines are priced.
Should I compare timelines between ADU quotes?
Yes. Ask each contractor for a schedule by phase, from design and permits through construction and final inspection.
Does a new detached ADU need solar panels in California?
Generally yes. A newly constructed detached ADU needs newly installed solar under the 2025 Energy Code unless an exception applies.
Get an ADU Quote Built From Your Temecula Lot
In short: Ask for a quote that passes every line of the checklist, starting with a site visit.
Hold every quote to this checklist, ours included. Spencer walks your lot before writing a number, checking your panel, slope, and drainage [8]. Our proposals list site work, permits, materials, and labor as separate lines, so they fit your side-by-side table [8]. Check our license, B-842038, on CSLB like any other [6][8]. For a free site visit on your ADU project, call (951) 551-6165 [8][9].
Sources
In short: Each numbered citation in the article matches an entry below.
- Woollard Construction, what an ADU costs in Temecula, 2026. Accessed September 10, 2026.
- California Legislature, SB 543 (McNerney), Chapter 520, Statutes of 2025, Government Code 66311.5, approved October 10, 2025.
- Temecula Valley Unified School District, Developer Fees, rates effective June 16, 2026. Accessed September 10, 2026.
- Contractors State License Board, Home Improvement Payment Reminder, 2026. Accessed September 10, 2026.
- Contractors State License Board, Industry Bulletin 22-14, Progress Payment Restrictions, November 22, 2022.
- Contractors State License Board, Check a Contractor License, 2026. Accessed September 10, 2026.
- California Business and Professions Code, Section 7159.5, 2025 code. Accessed September 10, 2026.
- Woollard Construction, 2026. Accessed September 10, 2026.
- Woollard Construction, ADU design and build services, 2026. Accessed September 10, 2026.
- California Energy Commission, 2025 Energy Code Support Center: General Information on ADUs, 2026. Accessed September 10, 2026.
Spencer Woollard
Spencer Woollard has 30+ years of experience in custom construction in Southern California. With over 350 completed projects including ADUs and bathroom remodels, Spencer is a trusted local contractor in Temecula, CA.
