That Unpermitted Addition Just Cost You $50,000, Now What?

What every California homebuyer should know about damages when the dream home hides a defect.

You toured the house three times. You walked the yard, opened every cabinet, and pictured your weekends in that oversized garage addition working on your projects. The inspection contingencies came off, escrow closed, and the keys were yours.

Then the city told you the garage addition was never permitted — and bringing it up to code would run at least $50,000.

If this sounds like a hypothetical, it is. It is also a very real fact pattern we see at Tierney Law Group, in one form or another, almost every month. The unpermitted addition, the leaking roof painted over the morning of the open house, the failing foundation buried under fresh landscaping — the details change, but the question for the buyer is always the same: who pays for this, and how much can I actually recover?

The answer in California is more nuanced than most buyers expect.

You will not necessarily get a check for the repair estimate

Most buyers assume the math is simple: get a contractor’s bid, send it to the seller (or the seller’s agent), and demand that number. In real life, California law rarely lines up that cleanly.

Under California Civil Code § 3343, a buyer who has been defrauded in the purchase of real property is entitled to recover the difference between what they paid and the actual value of what they received — the so-called “out-of-pocket” measure of damages. The statute also allows recovery for additional damages proximately caused by the fraud, including reasonably expended consequential costs and loss of use.

In plain English: the law generally awards you the diminution in value — how much less the property is worth because of the defect — or the cost of repair, whichever is less. Subjective frustration, sticker shock, and the cost of finally building the garage you imagined are not, by themselves, recoverable.

That distinction is where a lot of buyers — and a lot of attorneys — get into trouble.

Cost of repair versus diminution in value

Imagine a poorly built, defective backyard jungle gym. It might cost $50,000 to replace, but the market may assign it little to no value at all. A buyer who shows up to mediation with a $50,000 contractor’s estimate and nothing else is going to be disappointed. The market simply does not price homes by adding up the cost of every feature inside the fence line.

Diminution in value is the difference between the fair market value of the property at the time of closing and what it would have been worth without the defect. Establishing that number generally requires a qualified, third-party appraiser — not the buyer’s gut, and not a single contractor’s bid. Buyers who skip this step often face an uphill battle proving any actual loss, even when the defect is real and the seller’s nondisclosure is clear.

A single repair quote, by contrast, tends to be the highest estimate a buyer can find. Defense counsel and mediators recognize that immediately, and credibility suffers. Multiple estimates, properly documented receipts, and — when the numbers warrant it — a formal appraisal are what move a case forward.

When you can recover more: the “benefit of the bargain”

California is not entirely unforgiving. Civil Code § 1709 provides that one who willfully deceives another with intent to induce action is liable for any damage the other person suffers. In the right circumstances, a buyer can recover under the broader “benefit of the bargain” measure — the difference between what was promised and what was actually received.

The California Supreme Court applied this rule in Alliance Mortgage Co. v. Rothwell (1995) 10 Cal.4th 1226, and the Court of Appeal extended it to a real estate agent’s affirmative misrepresentation in Fragale v. Faulkner (2003) 110 Cal.App.4th 229. Where a seller’s agent owes a fiduciary duty to the buyer and affirmatively misrepresents (or conceals) a material condition, the broader benefit-of-the-bargain measure can come into play — and the recovery can look very different from a straight diminution analysis.

That is the moment when “what did the agent know, and when did they know it” stops being a rhetorical question and starts being the case.

The lesson for buyers

The unpermitted garage bay, the hidden leak, the patched foundation — these claims rise and fall on three things: documentation, valuation, and the precise legal theory pleaded. Buyers who walk in with a single repair estimate and a sense of grievance generally walk back out months later, several thousand dollars lighter in fees, and forced to start over with a properly supported demand.

Buyers who come in with the right appraisal, the right damages theory, and counsel who understands the difference between Civil Code §§ 3343 and 1709 tend to resolve their cases faster — and for a number that actually reflects their loss.

How Tierney Law Group can help

Tierney Law Group represents California homebuyers, sellers, and brokers in real property disputes involving nondisclosure, fraud, construction defects, and post-closing repair claims. We work with appraisers, licensed contractors, and construction-defect experts to build damages cases the right way from day one — so our clients are not the ones spending a year in litigation only to discover their number was never supportable.

If you have recently purchased a home in California and discovered an undisclosed defect, unpermitted work, or a material misrepresentation by a seller or agent, the window to act is shorter than most buyers realize. Evidence disappears, memories fade, and statutes of limitations run.

Contact Tierney Law Group today for a confidential consultation. We will help you understand whether you have a claim, what it is realistically worth, and what it will take to make you whole.

This post was inspired by Robert J. Sunderland’s article, “Real property claims: Buyers beware,” published in the Daily Journal Verdicts & Settlements supplement (May 8, 2026). It is provided for general informational purposes only and does not constitute legal advice. Reading this post does not create an attorney-client relationship with Tierney Law Group. For advice on your specific situation, please contact our office.