It was bound to happen. Less than four months after officially turning over the executive vice presidential seat of the National Association of Home Builders, Nathaniel H. Rogg has a new job. Or, officially, a "commission."

The U.S. League of Savings Associations has hired Rogg to draft a program aimed at "expanding the housing rehabilitation industry, including promotion of increased lending in city neigborhoods." Rogg has responded with his usual enthusiasm. He's been walking inner city streets of Washington, Chicago and Cincinatti, where rehabilitation and renovation is being undertaken by thousands of Americans.

Rogg's first goal is to find out how much housing preservation is taking place and where. "Most of it seems to be individually stimulated," he said. His next move will be evaluation and an identification of problems and a crack at how to overcome them.

Rogg has changed hats quickly. Once the staff head man for builders of new housing, he heard his new boss, John A. Hardin, president of the USLA, say: "We Americans cannot go on forever building new houses and apartments on the outskirts of cities and letting older housing rot from neglect. We have seen the consequences of wasting energy and natural resources."

of course, Rogg already knows the inner city. He bought a town house in the 1700 block of Q Street NW more than a decade ago for less than $40,000 and spent a small bundle to rejuvenate and modernize it. Now it would sell for considerably more than $100,000. He and his wife love the house, except for occasional security problems.

In regard to an enthusiasm for rehabilitation, Rogg tells a story about George Behymer, an executive of an S&L in Cincinnati. "He not only arranges loans on inner-city houses in which his thrift institution has an interest but he also goes out and does some paperhanging. The smell of the paste and trimming and hanging seem to turn him on," Rogg said.

The Montgomery County residential forecast predicts a 95 per cent increase in new single-family houses, for a likely total of 1,780 this year, and a 125 per cent upturn for new town houses - for a total to 11,115, an indication that there may be too many new town houses being built in the county. New multi-family units will be up 51 per cent to 945 new units in 1977, the researchers report.

Contrary to some popular misconception, new houses are getting larger. The economic research staff of the National Assocaition of Home Builders reports that the average size was slightly more than 1,600 square feet in 1976, up 2 per cent over the average in 1975.

Mortgage rates at some S&Ls may be moving up slightly. John U. Raymond, president of Home federal Savings and Loan, proffered a new rate card with slightly higher rates, with the best rate being available in D.C. at 8.5 per cent, plus one discount point, for a loan of up to $55,000 with at least a 20 per cent down payment.

Nate Simon, general manager of the award-winning Twin Lakes houses that Soutern Engineering is building at Burke Center, said that R-30 insulation is used in the ceilings and R-13 batts of fiberglass in the walls and R-19, 6-inch batts over the ceiling in the garage-basement, Crawl spaces get R-11 insulation. The houses have oil-fired heat.

The developers of the proposed Paper Mill town houses in Georgetown reported 37 early sales deposits for town houses averaging $95,000, with construction not scheduled to begin until later summer . . . And the Edward R. Carr firm annouced 57 presale deposits for new single-family houses in the Signal Hill subdivison in Fairfax County's Rolling Road are.

Eleanor Cozini, sales agent (for Town & Country) on the scene at ridgelea Hills in Fairfax's Mantua area, said that traffic has been heavy and that 39 of the dwellings have been sold, with prices ranging from $138,000 to $160,000. "Most of the buyers come from a five-mile radius because of schools and conveniences. Even out-of-towners seek out this area," she said. Associated Builders is the developer.

Sales are reported strong at The Seasons, a condominium conversion of medium-rise buildings by Lincoln Property Co. in South Alexandria. John Chirtea, a partner in LPC, said: "Yes, we had a challenge on our hands but we knew that The Seasons was a sleeper. We completely renovated and modernized the 10-year-old units and added an extensive recreational package, park-inspired landscaping and an attractive pricing package." The first three buildings have been sold out, with two more to go.

Three brothers named Foster operate a firm that builds single-family houses in the LOng Branch subdivision in Fairfax County. Two are named Art and Ken but the happiest currently is Don. He got a hole-in-one Tuesday at an Optimist Club golf outing at Washington Golf and Country Club. He used an eight-iron on the 148-yard No. 2 hole. The shot hit the green and trickled in. Later, he learned that a $500 purse was attached to the feat.But will his brothers be able to live with him?