A. Joseph Howar, a Washington builder and developer who was a founder and the master builder of the Islamic Center and Mosque on Massachusetts Avenue here, died Feb. 27 in his home in Washington after a stroke.

Mr. Howar was born near the Mount of Olives more than 100 years ago. He came to this country in 1903 and began his business career in this city later that year when he opened a women's clothing store on F Street. Soon after that, he became a Washington builder, specializing in houses and apartment buildings.

During the depression, he and the building industry at large fell on hard times. In addition to his construction business, he owned and operated a small restaurant near the intersection of 14th and U streets NW and a women's clothing store on Connecticut Avenue.

He re-entered the construction business in 1935, developed apartment projects in Northern Virginia, and by all accounts prospered. He was active in the local Arab community and gained recognition for his philanthropic work. (He built both a school and a mosque for his native village.)

He became the founder of the Washington Mosque Foundation, set up to collect funds and build a mosque for the area Islamic community. Mr. Howar donated time and money, and to a large extent, he built the mosque.

President Dwight D. Eisenhower attended its dedication ceremony in June 1957, and presidents and kings, as well as members of the Washington Islamic community, have worshipped there.

Mr. Howar received decorations for his work over the years from Jordan's King Hussein and the late Egyptian President Gamel Abdel Nasser.

Mr. Howar's wife of 54 years, the former Badira Haki, died in 1981. His survivors include two sons, Raymond J. and Edmond N., both of Washington; three daughters, Patricia Howar Helmig of Washington, Joyce Howar Stefanik of Coral Gables, Fla., and Nancy Howar O'Sullivan of Washington and New York City; a brother, Meheddin Issa Abu-Hawa of the Mount of Olives, and 17 grandchildren.