This party could get pooped.

City Buildings Department authorities said yesterday they’ve launched a probe of the jampacked, booze-fueled Sunday-afternoon shindigs on the rooftop pool deck of the swanky Gansevoort Park Avenue Hotel.

“We will take the appropriate action based upon what we find,” said Buildings spokesperson Ryan Fitz-Gibbon, a day after The Post reported that as many as 300 people partied on the pool deck Sunday in a space with a maximum occupancy of 54.

The hotel’s Summer Series parties, featuring top DJs spinning thundering dance tunes from the 19th-floot deck, are infuriating neighbors on East 29th Street, who just want a little peace and quiet on their Sunday afternoons.

The parties also appeared to flagrantly violate capacity limits listed on the hotel’s certificate of occupancy — raising questions about safety in case of a fire or other emergency.