Affordable housing is increasingly difficult to find in Northern Virginia, and local governments are "widening the affordability gap" with increased fees, the 900-member Northern Virginia Builders Association has charged.

"We have come to a point where local government has to get involved if we are to produce affordable housing," said Tony Ahuja, director of the technical services division of the association.

In a report scheduled for release next week, the builders group said that more than 100,000 Northern Virginia families could not afford to buy a median-priced three-bedroom home there in 1983.

"When we speak of affordable housing, we are not talking exclusively about starter homes. We are talking about reducing the costs of development for all new homes," the local builders group said in its report, entitled "Housing Affordability in Northern Virginia."

The lack of affordable homes is a growing problem across the nation. The Virginia builders association's criticism of regulations and land-use and zoning policies mirrors complaints of builder groups elsewhere and the National Association of Home Builders, which apparently are waging a nationwide battle to ease local governmental restraints on the home-building industry.

The local shortage of affordable housing near major centers of employment, such as Tysons Corner, "wreaks havoc on our highways," the report said. "Families forced farther and farther away from where they work to find housing they can afford have no choice but to join the thousands of commuters on our already crowded roads."

However, the same report criticizes local government requirements for "off-site" improvements in the rezoning process. Those "off-site" improvements are almost always road or traffic improvements.

"Affordable housing can be a reality, but not without the serious support of the public sector," according to the report. It was prepared by the association's technical services division at the request of association President William L. Berry, president of William L. Berry Inc., a Maryland-based home construction company with extensive developments in the Washington suburbs.

However, one Fairfax official, who asked not to be identified, said builders are always trying to come up with ways to cut costs. "Now they are trying to blame increasing building costs on building codes and standards designed to properly guide growth under the county's comprehensive land use plan," he said.

"The Fairfax Board of supervisors is very concerned with developing an affordable-housing program, especially one that can help families on the lower end of the county's income levels."

Underlying the report is the issue of who pays for growth -- current residents and taxpayers or builders and future homeowners.

When the costs of such things as sewer hookups and road improvements are borne by builders, they show up in the prices of new homes, making them harder to sell,the report says. Consequently, builders here and elsewhere recently have made much of their commitment to helping young and other moderate-income families overcome the "affordability problem."

Many critics argue, however, that this commitment amounts to nothing more than unloading the costs on someone else -- the taxpayers -- so that new houses will be easier to sell.

In addition, homeowners who are already settled in point out that they made large investments based on existing zoning and land-use plans and contend that they have a right to expect the local jurisdiction not to change the rules on them.

The report says local governments can help cut costs of housing by reducing the time needed to get land rezoned and permits issued. It also calls on local governments to allow higher-density zonings, including construction of detached homes on smaller lots than are permitted normally, and for higher concentrations of town houses, multifamily developments and apartments or condominiums near employment centers.

The question of affordability and the criticism of local government regulations "go hand in hand," Ahuja said. "The politicians don't realize their decisions affect the costs of construction."

In addition, the report calls for reduced health and safety regulations, which the builders claim "are excessive" and drive development costs and home prices up.

The report concentrates on the affordability gap, the difference between what families earn and what is needed to buy a home. Families earning the national median income in August fell 17 percent short of the income necessary to qualify to buy the nation's median-priced home, the report says.

Median family income in " Northern Virginia in 1983 ranged from $27,000 in Manassas Park to $41,500 in Fairfax County. At the same time, the median sales price of three- to four-bedroom homes averaged $104,700 in the area, according to the builders group.

With a 20 percent down payment and an assumed interest rate of 12.73 percent (based on Washington's 1983 average as reported by the Federal Home Loan Bank Board), the monthly payment -- including principal, interest, insurance and taxes -- would top $1,000, the report said.

This means the average Fairfax family would have to spend more than 31 percent of its monthly income to buy that median-priced home, and the average Manassas Park family would have to spend 47 percent. By contrast, most lenders generally figure that a buyer can qualify for a loan if those payments do not exceed 25 to 30 percent of monthly income.

The report claims that families with annual incomes higher than the median, but less than $45,400, generally could not qualify for that 80 percent loan. But several local real estate agents said they thought they would be able to place similar loans depending upon debt ratios and credit histories.

"Although statistics are not readily available on the exact number of families that fall into the local affordability gap, of the 306,500 families in the Northern Virginia Planning District, we know that, if the family with the median income can't afford it, the 150,000-plus families earning less than the median can't afford it either," the report says.