Clairemont, San Diego · Equity, ADUs and rental income

A San Diego ADU bid of $275 to $350 a square foot is not a red flag. It is close to the local number.

The thread compares a Phoenix bid to San Diego quotes, and the poster is clear they are building here, not there. That $275-$350 spread is the actual number to plan a loan amount around.

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The answer

The direct answer

A San Diego owner shopping ADU bids reported quotes running $275 to $350 a square foot locally, against a $185 a square foot bid seen out of Phoenix. That gap is not a sign of being overcharged. It reflects real labor and permitting cost differences between markets, and it is the number to plan a construction loan amount around.

What changes the answer

Got a bid for $185 a square foot for a detached ADU in Phoenix, is San Diego really that much more?
How much does an 800 square foot ADU cost in San Diego?
Should I compare San Diego ADU bids to quotes from other states?

Each one is answered further down this page, and any one can move the outcome on a specific file.

The local number: Adam King’s Corcoran Icon Properties listing at 4674 Boxwood Dr sits on a 9,100 square foot R-1 lot, the size and zoning profile that supports a detached ADU build in this corridor.
Rule and source: Adam King, Corcoran Icon Properties, listing record
Last verified: September 1, 2026

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Answered by Nick Nagy · 23 years · NMLS 314880 · CA DRE 01444600 · Mortgage financing through Loan Factory, 237 lenders · Run this answer against my numbers →

Part of the California Mortgage Answer Desk, and of the Clairemont questions.

How it works

Why the San Diego number runs so far above other markets

A homeowner comparing bids across markets found a $185 per square foot quote out of Phoenix against $275 to $350 per square foot from San Diego contractors for a similar detached ADU. That is a wide spread, and it is a fair thing to question when you are the one paying for it.

The gap is largely explained by labor cost, local permitting complexity and demand for ADU-specific contractors, all of which run higher in San Diego than in many other Western markets. It is a real local premium, not evidence that any single bid is inflated.

The detail that matters

What this means for sizing a construction loan

If $275 to $350 a square foot is the honest local range, an 800 square foot detached ADU lands somewhere between $220,000 and $280,000 before soft costs like plans and permits, which the earlier cost breakdown put in the $6,000 to $11,000 range on their own. Planning a loan amount around the low end of that range is how ADU budgets run short partway through construction.

This is where financing structure matters as much as the total number. A construction-to-permanent loan sized to the realistic high end of the local per-square-foot range, rather than an optimistic low bid, is what keeps a project from stalling when the actual invoices come in higher than the first estimate.

How it works

Comparing bids is smart. Comparing them across markets is where it goes wrong

It makes sense to shop multiple bids before committing to a contractor. Where it goes wrong is using an out-of-market number, Phoenix, Texas, or anywhere with a different labor and permitting environment, as the benchmark for what a San Diego build should cost.

The useful comparison is other San Diego bids against each other, not San Diego against a different state. Once the local range is clear, the financing conversation gets much easier, because the loan amount can be sized to reality instead of to the cheapest number seen anywhere.

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Where this question came from

Someone asked this in public

Got a bid for $185/sq ft for a detached ADU in Phoenix…
Reddit r/AccessoryDwellings, captured 2026-08-10 (LH1 demand sweep)

If nobody gave a straight answer in that thread, that is not the person missing something. The answer depends on a specific file and a specific address.

Who answers

Nick Nagy

23 years in California lending · NMLS 314880 · CA DRE 01444600 · Loan Factory, Inc.

Dual licensed, so the loan side and the real estate side of a move get looked at as one problem instead of two. Most of what goes wrong in a move is a timing problem wearing a financing costume, and it is cheaper to catch it before you write an offer than after.

Financing is placed through Loan Factory, Inc. Real estate work is under CA DRE 01444600. More about Nick.

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The desk behind the file

One file, 237 lenders competing for it, and a broker who has done this for 23 years.

Loan Factory, Inc. is the brokerage. These are its published figures.

20,907+Loan Factory Google reviews

5.0Loan Factory average rating

237Lenders available through Loan Factory

48States Loan Factory is licensed in

A retail bank has one guideline book. A broker shops the same file across the shelf and finds the lender whose box it already fits.

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Straight answers

Questions people here actually ask

The follow-on questions, answered in the order they get asked.

Got a bid for $185 a square foot for a detached ADU in Phoenix, is San Diego really that much more?

Based on forum-reported bids from a San Diego homeowner shopping contractors, yes. Local quotes ran $275 to $350 per square foot against the $185 per square foot Phoenix bid in the same comparison. The gap reflects real local labor and permitting cost differences, not an inflated San Diego quote.

How much does an 800 square foot ADU cost in San Diego?

At a reported local range of $275 to $350 per square foot, an 800 square foot detached unit runs roughly $220,000 to $280,000 before plans and permits, which typically add another several thousand dollars. Sizing a construction loan to the higher end of that range avoids running short mid-build.

Should I compare San Diego ADU bids to quotes from other states?

It is useful context but not a fair benchmark. Labor and permitting costs vary widely by market, so the more reliable comparison is multiple San Diego bids against each other, then sizing the construction loan to that local range.

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