Text PJ directly. Photo of the bid, PDF, or the key numbers. ADU quotes are complex — we'll respond with specific, plain-language feedback, usually within the hour during business hours.
Text 773-544-1231Yes. Quote review is always free at SideGuy. We don't take referral fees from ADU builders and we don't sell design or build services. Our only interest is giving you honest guidance before you sign a six-figure contract.
A detached ADU in San Diego typically runs $275–$425 per square foot all-in (including permits, design, and site work). A 500 sq ft unit: $140,000–$215,000. A 1,200 sq ft unit: $330,000–$510,000. Garage conversions run $80,000–$150,000 depending on existing structure. Manufactured/prefab ADUs can be less but have their own site-work cost considerations.
From initial planning to certificate of occupancy, expect 12–18 months for a detached ADU. Permitting alone typically takes 3–6 months through the City of San Diego, though pre-approved ADU plans can shorten that. Garage conversions run faster — 6–10 months total is realistic.
Not always required, but often advisable if you plan to rent the unit. SDG&E and the city have rules about separate metering. Your contractor should be able to explain the options and the cost difference. If they can't, that's a gap in their ADU expertise.
Especially then. Design-build ADU companies in San Diego have grown rapidly in response to state law changes, and quality varies significantly. Some are excellent; others are undercapitalized or have thin margins that lead to value engineering mid-project. The same review criteria apply.
Yes — several options: HELOC, cash-out refinance, construction loan, or CalHFA ADU Grant Program (up to $40,000 for eligible homeowners). Financing terms significantly affect the real total cost of your ADU. If the builder is quoting you a "monthly payment" without discussing loan terms, text us before you proceed.
That's a significant flag. A legitimate ADU builder — especially one asking for $150,000+ — has no reason to object to a homeowner taking 24 hours to have an independent party review the proposal. Resistance to scrutiny on a major contract is itself a reason to reconsider.
How to find and vet an ADU contractor in San Diego — what to ask and what to check.
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All ADUs require City of San Diego (or local jurisdiction) building permits. Utility connections require SDGE and SDWD coordination. Permit timeline in San Diego typically runs 4–12 months. Budget $300–$1,500 for permit fees on mid-range projects. Permit fees are a legitimate hard cost — any quote that omits them is understating the true project cost.
$65–$120/hr general labor; licensed trades (electrical, plumbing) run $110–$180/hr. On a typical project, labor accounts for 30–50% of total quoted cost. The specific crew skill level, travel distance, and San Diego's high cost of living all push labor rates above national averages.
Framing lumber runs 30–40% of rough construction cost. Finishes vary widely — prefab/panelized systems can reduce material costs 15–25% vs. stick-frame. Material prices in San Diego track 8–15% above national averages due to supply chain routing and local fuel costs. Ask for a materials breakdown — understanding what you're paying for reduces negotiating friction.
GC overhead and profit on ADU projects: 18–28% of total hard costs. Design/permit fees are often 8–15% of total project cost and should be itemized separately. Margin itself is not a problem — contractors need it to sustain a licensed, insured business. The problem is when margin is hidden inside inflated line items rather than stated transparently.
Every contractor doing work in California must hold a current, active license from the Contractors State License Board (CSLB). For adu work, the relevant classification is Class B (General Building Contractor) required for full ADU construction.
The CSLB lookup takes 60 seconds and shows: current license status, bond amount, workers' compensation status, and any enforcement history. A contractor who discourages you from verifying their license is a contractor worth reconsidering.
What to verify: license number matches the contractor entity on your contract, license status is "Active," bond is current, and workers' comp is in force (or contractor has a valid exemption).
The lowest bid on a adu project in San Diego is not always — and not usually — the best value. Low bids typically mean one of three things: scope has been omitted, permits are being skipped, or the materials specification is lower-grade than the competing bids.
A complete, honest bid that is 15% higher than the lowest quote is almost always the better financial decision. The cost of a failed inspection, a scope dispute, or unpermitted work discovered during a future home sale typically exceeds the initial bid difference by 3–5x.
The right question is not "who is cheapest?" but "whose quote is most complete?" A bid that accounts for permits, proper disposal, licensed subcontractors, and a written warranty is protecting your investment — not inflating it.
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About This Review
Reviewed with 20+ years of local contractor pricing exposure across San Diego County. SideGuy does not sell construction services, accept referral fees from contractors, or take any compensation tied to your hiring decision. We review quotes before you commit. Clarity before cost.
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