Mary-Kate Olsen, Olivier Sarkozy renovating home

Mary-Kate Olsen and her fiancé Olivier Sarkozy are renovating their already epic Turtle Bay Gardens townhouse for $3 million, according to property records filed with the city Tuesday.

The permit for the renovation on the landmarked home calls for a 396-square-foot extension to the home, as well as a “change in exits/regress.”

The 45-year-old half brother of the former French president and the 28-year-old actress, who earned fame portraying Michelle Tanner in “Full House,” are renovating the more than 8,100-square-foot home that initially came with a hall of mirrors and a pool. The five-bedroom townhouse also includes a private garage, a ballroom, an elevator and an artist’s studio. After the renovation, the home will be more than 8,500 square feet.

Library at 226 East 49th Street

The couple took out a $3 million mortgage on the townhouse earlier this year, according to city records.

Architect of record Steven Harris declined to comment.

Hallway of mirrors at 226 East 49th Street

Olsen and Sarkozy bought the home at 226-228 East 49th Street – located in a stretch of town houses between 47th and 48th streets and Third and Second avenues – in April for $13.5 million from painter David Deutsch.

The couple previously lived in a five-bedroom townhouse in the East Village, which Sarkozy bought in 2012 for $6.25 million. He sold the property to artist Aaron Young for $6.4 million in January.