In a newly leased office in the Dulles International Airport terminal, brokers Charles Warner of Middleburg and James Tyler of Leesburg are setting up an international firm designed to serve foreign and domestic buyers of income-producing properties. Warner said that H. Jackson Pontius, former executive vice prisicent of the National Association of Home Builders, will be senior vice president. Pontius will set up a group of corresponding brokers throughout America to provide listings of properties (none less than $500,000) available for investors.

Walter A. Kehoe, president and chief operations officer of Ryland Homes' eastern area, said the the firm plans to introduce a new line of houses, including a model that can be built with only one bedroom -- in Columbia this spring. Kehoe said the contemporary design should appeal to young and single buyers.

That's mixed-use eight-story office building under way at 2501 M St. NW, opposite the Westbridge. It is being developed by a group that includes builder Melvin Lenkin and was designed by architect Vlastimil Koubek. It will have 100,000 square feet of office space on lower floors and 38 luxury condominium apartments on upper floors. The Julien Studley firm is leasing the office space and Burr, Morris & Pardoe is handling the apartment sales.

Developer Jeffrey N. Cohen, who has asked the Ben Bow restaurant-bar to vacate the first floor of 1636 Connecticut Ave. NW, plans to modernize the old building and set up his own office there. He also bought a parking lot next door from APA for $620,000 and plans to build a Victorian-style condominium apartment building with stone and brick exteior trim. GMR of Gaithersburg is the architect. Cohen said the two-bedroom apartments probably will bepriced for more than $130,000.