I live in a condo building and someone just bought the unit next to us and is starting construction without permits. What's our recourse?

In a word, tattle, say our experts. But keep in mind that depending on the work, your neighbor's project may actually be above board.

"Notify the Board of Managers and the managing agent, and confirm whether any permits for the work are necessary," advises Jeffrey S. Reich, a real estate attorney with Schwartz, Sladkus, Reich, Greenberg, Atlas LLP, who notes that for certain decorative upgrades like painting, wallpapering, most flooring work or installations, and hanging of cabinetry, no permits are required.

If that doesn't lead to a satisfactory resolution, Reich recommends calling 311 to report the unauthorized work. (He also notes that if you live outside of the five boroughs, you may need to contact whatever local building department has jurisdiction in your area.) "If the work is, in fact, being performed without the necessary permits, the City should be prepared to shut the work down," he says. If it's already finished by the time your complaint goes through, the city could require your neighbors to submit post-work filings. And you should probably brace yourself for some tense exchanges in the elevator with your new neighbor.

Virginia K. Smith is the senior editor at BrickUnderground.com, the online survival guide to finding a NYC apartment and living happily ever after. To see more expert answers or to ask a real estate question, click here.