"Grandfathering": What It Really Means for an Older Building

Buildings are generally expected to comply with the code edition in force when they were built, not every edition that's come out since. That's the basis of "grandfathering" — a legally built structure doesn't become illegal overnight because the code was updated. It's a practical rule; requiring every existing building to be retrofitted every time the code changes wouldn't be workable.

But grandfathering isn't unconditional. A renovation, an addition, or a change of use can trigger a requirement to bring some or all of the building up to current code, and life-safety items like fire alarms are treated more strictly than cosmetic ones. If you're buying an older property, ask what's actually grandfathered and what isn't before you assume everything's fine.