ADU Construction Bid Teardown: Line by Line, With the Red Flags
A detached, ground-up 600 sq ft one-bedroom ADU in Los Angeles. The quote was $295,000 — about $492 per sq ft. Here's the breakdown.
Representative, anonymized example built from common 2026 Southern California bid patterns — not a specific client's project. Ranges reflect current market pricing.
At ~$492/sq ft this runs about 20% over the ~$400/sq ft norm for a standard SoCal ADU. Worse, the two lines most likely to blow up later — utility connections and contingency — are 'included' or missing entirely.
The bid, line by line
| Line item | Quoted | Fair | Flag |
|---|---|---|---|
Plans, structural engineering & permits Design + structural + city fees for a standard ADU. High end — ask what's design fee vs. city pass-through. | $28,000 | $15,000–$22,000 | Check it |
Site work & foundation Reasonable for a slab on a typical lot. Confirm no major grading or soils issues are excluded. | $42,000 | $30,000–$40,000 | Check it |
Framing & exterior shell In range for framing, roof, windows, and siding on a 600 sq ft unit. | $68,000 | $55,000–$70,000 | Fair |
Plumbing (rough + finish) Slightly high. Ask how much is the connection to the main vs. in-unit plumbing. | $26,000 | $18,000–$24,000 | Check it |
Electrical + panel A panel or service upgrade is often needed — confirm whether it's included here or will be a change order. | $24,000 | $16,000–$22,000 | Check it |
HVAC (mini-split) A single mini-split for 600 sq ft is typically $8,000–$12,000 installed. | $14,000 | $8,000–$12,000 | Check it |
Kitchen + bath finishes Should be allowance-based so you control finish levels. Ask for the allowance amounts. | $33,000 | $22,000–$30,000 | Check it |
Utility connections (sewer/water tie-in) Utility connections are the #1 ADU cost surprise and vary wildly by lot. 'Included' with no scope is a major risk — get the assumed trench distance and method in writing. | "included" | $8,000–$20,000+ | Red flag |
General conditions / overhead & profit Ground-up construction with no stated O&P means it's hidden in the line items — impossible to compare against other bids. | not listed | 15–20% | Red flag |
Contingency Building from the ground up without a contingency line is unrealistic and guarantees change orders. | none | ~10% on ground-up | Red flag |
The red flags, summarized
- $492/sq ft — about 20% over the ~$400/sq ft norm for a standard ADU.
- Utility connections 'included' with no scope — the single biggest hidden ADU cost.
- No general-conditions or overhead-and-profit line.
- No contingency on a ground-up build.
- Finishes quoted as fixed lines rather than allowances.
What to do before you sign
- Get the utility-connection assumptions (distance, method) in writing as a line item.
- Require explicit overhead & profit and contingency lines.
- Compare the $/sq ft against the county ADU cost page before you sign.
- Make all finishes allowance-based so you control the level.
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