Loudoun County officials yesterday increased the fees developers are expected to pay when they ask to rezone land for new houses--making those charges among the highest for builders anywhere in the state, according to industry officials.

The Loudoun Board of Supervisors said the county would ask developers to pay $10,712 per dwelling for many of the single-family houses they build. Under Loudoun's old rules, the expected payment varied between $4,550 and $10,290 per house, depending on location.

Loudoun, the region's fastest growing county, is the latest Virginia locality to try to get developers to cover more of the cost of building new schools, libraries and other public buildings demanded by burgeoning populations.

Last year, Prince William County supervisors agreed to a graduated increase that eventually will be as much as $15,250 per house. Officials set the higher level--which won't be reached until 2001--in an effort to slow the pace of home building.

And in June, Spotsylvania County supervisors called for developers to pay $8,800 per single-family house. Previously, projects had been analyzed on a case-by-case basis, and Spotsylvania officials said the supervisors' action represented an increase.

Representatives of the building industry warned that the fees would be passed on to buyers, driving home prices higher and diminishing the amount of affordable housing. They also said the higher charges would encourage sprawl by forcing people to move farther away from their jobs to find low-cost housing.

Natalee Grigg, legislative coordinator for the Home Builders Association of Virginia, said Loudoun's fees would be among the state's highest.

"This sort of increase cannot be absorbed in the regular cost of building," said Grigg, whose organization has asked state lawmakers to stop local officials from seeking the higher fees. "The customer will have to pay for these increases."

Loudoun Supervisor James G. Burton (I-Mercer) said new residents should pay more.

"The whole idea is to shift more of the burden of the new facilities onto the newcomers who are creating the need for the new facilities and shift the burden away form the longtime residents who have already paid over and over and over," Burton said.

Rapidly growing counties in Virginia say the contributions, called "proffers," are their best tool to help pay the costs of growth. Officially, proffers are voluntary contributions of cash or land, but counties have made it clear that they expect the payments in exchange for zoning approvals.

In 1997, Loudoun officials doubled the amount they expected in proffers, asking for 50 percent of the estimated costs for new facilities. Now some Loudoun supervisors want developers to pay 100 percent of those costs.

Until now, Loudoun asked for varying amounts in proffer donations, saying there were higher costs associated with building public facilities in certain parts of the county.

But county officials said that calculation had grown antiquated. Revised calculations of how much it costs to provide facilities for new residents show that the real costs are higher and more uniform. Part of the reason for the change is that the number of children in the average single-family house has increased, officials said.

The new guidelines, which will take effect in October, do not apply to the first 1.6 houses built per acre.

John A. Andrews II, head of the Loudoun chapter of the Northern Virginia Building Industry Association, said the uniform proffers do not take into account the fact that some areas already have schools in place.

"Asking the development community to pay for things that are already in place doesn't seem fair," Andrews said.

But Board of Supervisors Chairman Dale Polen Myers (R-At Large) said builders should pay the same amount across the county because the costs ultimately end up being similar.

CAPTION: Supervisors Chairman Dale Polen Myers (R-At Large) says developers should pay the same fees across Loudoun County because the costs end up being similar.