Joseph J. Magnolia, 61, the founder and president of Joseph J. Magnolia Inc., Plumbing and Mechanical Contractors, and a lifelong resident of the Washington area, died at Holy Cross Hospital on Sept. 5 following a heart attack.

In the 1930s, Mr. Magnolia, who was born in Washington, went to work as a welder at the Washington Navy Yard, where he received a Letter of Commendation. During World War II, he served in the Pacific in the Navy's Construction Battalion, the "Seabees."

After the war, he returned here and joined the General Services Administration as a plumber. He founded his own company in 1954 and continued to run it until his death. It is now in the hands of his sons.

Mr. Magnolia, who lived in Silver Spring, was a member of the National Association of Plumbing, Heating and Cooling Contractors. He also was a member of the parish of St. Bernadette's Catholic Church in Silver Spring.

Survivors include his wife, Virginia, to whom he was married for 38 years, of Silver Spring; one daughter, Mary Ann Judith, of Ashton, Md.; three sons, Joseph M. and Michael, both of Silver Spring, and John D., of Annapolis; three sisters, Catherine Peters, of Alexandria, Rosie Moorehead, of LaPlata, Md., and Annie Sell, of Hanover, Pa., and six grandchildren.