Jeremy Parker and Jiminie Ha, longtime friends and collaborators, knew they had to act fast on a listing about five years ago for a Philip Johnson-designed house in Newburgh, N.Y.

“We were shocked to find this house,” Mr. Parker said in an email. “Nobody knew about a Philip Johnson home in Newburgh,” Ms. Ha added.

The two were interested in buying it together as an investment but had some initial doubts about its authenticity — until inspecting the place in person.

“The bones were there,” Ms. Ha said. But the boxy, two-story house, perched atop a sloping hill, was in disrepair and previous owners had made design changes not in keeping with its midcentury-modern aesthetic. Known as the Wolfhouse, the structure was built in the late 1940s, around the same time as Johnson’s Glass House in New Canaan, Conn. (Johnson designed 25 houses during his career, one of which has since been demolished, according to a spokeswoman for the Glass House museum.)