In a major commitment to the future of downtown Washington, the owner of Garfinckel's announced plans yesterday for the renovation and refurbishing of the department store chain's 53-year-old flagship location on F Street.

No price tag was put on the makeover, which will begin later this year and be completed in 1986, but Orren F. Knauer, a vice president of Allied Stores Corp., Garfinckel's parent company, said the cost "is going to be in the millions. . . . Obviously it's going to be very expensive." The other nine stores won't be affected.

The renovation will add 10,000 square feet of selling space to the huge store's existing 130,000 square feet of sales area. A spokeswoman for the store said improvements in efficiency and store layout in the refurbishing would make the increase seem even larger. "In effect, you're picking up more than that 10,000 square feet," she said.

Knauer said the store's new look would not affect the Garfinckel's product offerings or merchandising philosophy. "The changes will be contemporary, but nothing will be done to change the character of the store," he said.

Garfinckel's spokeswoman, Aniko Gaal, said that, while the entire interior of the building will be refurbished, particular attention will be paid to three sales floors: the third (which stocks designer dresses and shoes), the fourth (sportswear and special occasion clothing) and the seventh (home furnishings). She said that the remodeling of the third and fourth floors will use the "cathedral plan," which redirects customer traffic on the floor into a circular pattern, exposing more merchandise to customers. "We're creating a more comfortable traffic flow than we have, which is better for merchandising," Gaal said.

Details on what the renovated store would look like were scanty, but Gaal said the basic design and color scheme would be based on neutral colors. "The decor and the color scheme will probably be something that will gracefully age through the ages," she said.

Allied officials said the plans to refurbish the store, which is situated on F Street NW between 14th and 15th streets, represented a renewed commitment to Washington's downtown. "Obviously, we feel that the downtown area is a place we want to be well-represented," Knauer said. "It is a major commitment to Washington."

In a statement, Allied, which operates 544 stores under various names across the nation and has owned Garfinckel's since 1981, cited Metrorail and the new Washington Convention Center as reasons for its increased interest in the downtown location.