The public relations powerhouse BerlinRosen is expanding to 24,500 square feet at 15 Maiden Lane.

The firm has 17,500 feet in the downtown building that sits between Broadway and John Street.

They will take over the additional 7,000 feet on the fourth floor later this year through a sublease. The company started here in 2007 with just shy of 5,000 feet and now has the entire 11th, 15th and 16th floors. Asking rents are $42 a square foot.

Ari Waldman of Lee & Associates NYC represented the p.r. company, while the sublandlord was represented by Lee colleagues Greg Gang and Catherine O’Toole.