Non-conforming use

A property use that was legal when it started but no longer meets current zoning. It's usually allowed to continue, but with limits on rebuilding or expanding.

Also called grandfathered use · Properties & types · Updated September 2026

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Part 1 of 4

Why a seller cares

A grandfathered use, a duplex in a single-family zone or a shop on a residential street, is allowed to continue but not always to expand or rebuild. Buyers and their lenders ask whether the use survives a fire or a sale.

Part 2 of 4

A simple example

Your home has been a legal two-unit since 1961 in a zone that now allows one. A buyer asks whether they could rebuild both units after a fire.

Non-conforming use: a simple example
The questionWhere the answer lives
Can the use continue after a sale?Usually yes; the zoning office confirms in writing
Can it be rebuilt after a loss?Depends on the ordinance; some cut it off above a percentage of damage
Can it expand?Usually no without a variance

Non-conforming means allowed as-is. As-is is the limit.

Part 3 of 4

What people get wrong

That grandfathered means permanent. Many ordinances end the use if it stops for a year or the building is mostly destroyed.

Part 4 of 4 · where to read next

Where it appears in the sale

What a definition is, and what it isn't

Keighbor is a software company, not a law firm, brokerage, or tax adviser. This is general information, not legal, tax, financial, or real estate advice about your sale. Your situation may differ. Before acting on a contract, disclosure, title, tax, or pricing question, ask an appropriately licensed professional in your state.

Written and researched by Keighbor Research · drawn from the reference glossary · how we research and check what we publish

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