Joe Geeraert, 70, a Washington area home builder, died of cancer Friday at Suburban Hospital in Bethesda.

Since coming to this area about 1940, he had built about 3,000 homes in nearby Maryland and Virginia.

Mr. Geeraert was known particularly for his community of Twinbrook in Rockville, which eventually grew to several thousand units. Established in the early 1950s, it became known for its community activities and spirit.

He also developed Chandon near Dulles Airport in the early 1960s. Many of his homes were built in the low-and medium-priced ranges although he also built higher priced houses.

Mr. Geeraert, who lived in Bethesda, was a cofounder of the Suburban Maryland Home Builders Association and served as its president in 1957-58. He had been a director of the Metropolitan Washington Home Builders Association since serving as its president in 1960.

He was a director of the Suburban Virginia Home Builders Association and of the National Association of Home Builders since 1957. He was a director of the D.C. Housing Industry Corporation.

A member of the executive committee of the D.C. Builders Association, Mr. Geereart had been a director for five years. In October, the association presented him with its first annual Distinguished Service Award. aThe award was named in his honor.

He was born in Ghent, Belgium, where he studied architectural design at St. Luke Academy. He came to this country in 1931 and lived in Brooklyn, N.Y. In the late 1930s, he built several exhibits for the New York World's Fair.

Mr. Geereart was a board member of the Montgomery County Society for Crippled Children and Adults in Rockville. He had donated the land and built the facility in 1958.

He is survived by his wife, Marcia, of Bethesda; two daughters, Rosanne Carney and Dorothy Patterson, both of Rockville; four brothers and sisters, Georges, of Brussels, Marie-Johnson DeCock and Andre, both of Ghent, and Denise Beall of Fulton, Md. and six grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the Montgomery County Society for Crippled Children and Adults.