Charles Henry Grimm, 33, and Dennis W. Propst, 33, both brick mason foremen who had worked in Northern Virginia, were found dead Saturday morning in a car parked in the garage of friends they were visiting in Bridgewater, Va.

The cause of death was listed as accidental carbon monoxide poisoning, a spokesman for the Bridgewater police said.

Mr. Grimm was a native of Harrisonburg, Va., and came to this area in 1960. He was a resident of Alexandria.

Mr. Propst was born in Augusta County, Va., and came to Washington about 1970.

Both had worked for the Arch Masonry in Fairfax. Mr. Grimm had joined the company in 1964, and Mr. Propst had worked there for the past eight years.

Mr. Propst is survived by a brother, Larry, of the home in Falls Church; two other brothers, Michael, of Fairfax Station, and Jimmy, of Falls Church, and his parents, Mr. and Mrs. Ivan Propst, of Fairfax Station.

Mr. Grimm is survived by his parents, Mr. and Mrs. Earl Grimm, of Bridgewater; a brother, Donald, of Dayton, Va.; and four sisters, Blanche Losh, of Falls Church, Peggy Shull, of Mount Crawford, Va., Margaret, of Falls Church, and Betty Huddle, of Broadway, Va.