Mayor Eric Adams unveiled Thursday the largest overhaul of the Big Apple’s cumbersome zoning regulations in decades, as part of an effort to reshape development across the five boroughs.

The new rules will change regulation on issues from how much parking is required to how many studio apartments are allowed, officials said a briefing Thursday.

The sweeping reforms are the latest attempt by City Hall to put a dent in the ever-worsening housing crisis.

“There’s one thing that has barely changed since 1961 — New York City’s zoning laws,” Adams said Thursday. “So many of the issues we face are rooted in the ongoing housing crisis.”

“This is not tinkering around the edges, this is groundbreaking — literally”

One of the nixed rules is the restriction on New York City homeowners to build a second unit on spare space behind their house that they can rent out or retire.

Ditto are regulations that require just about every new housing development in portions of the outer boroughs near the subways to come with substantial amounts of parking.

Another set of tweaks aims to make it easier to build studios and smaller apartments in already-dense neighborhoods so existing multi-room units can go to families instead of roommates packed together.

The goal, said one official who was briefing reporters, is to wring more housing out of every neighborhood across the city instead of fighting years-long battles neighborhood by neighborhood to upzone.

The Big Apple is experiencing a massive housing shortage, causing ballooning rental costs.

The number of homes in apartments in nearly a dozen neighborhoods in NYC declined last year with production only concentrating in just a few areas.

This is a breaking story. Please check back for updates.