Houses, stores and other buildings as young as 50 years old may be eligible for inclusion in a new survey of historic properties in Loudoun County.

The survey of 750 properties is a response to residents' demands that the county's rich inventory of historic properties be protected from the rampant residential and commercial development of the past decade.

"We are scheduling this now while the leaves are off the trees," said Ray Ocel, senior planner for Loudoun County. "That is prime survey time."

The 2,200 buildings in Loudoun already on state and federal historic listings, many of which are pre-Civil War, will not be part of the county survey, Ocel said. The teams will be concentrating on structures built between the war and 1953, he said.

He said buildings such as motels, restaurants, train stations and family homes will be considered for inclusion.

Although being listed in the survey does not bring any economic benefits, Ocel said that might happen in the future if the county decides to use tax incentives to encourage preservation.

The surveyors from URS Corp. of Maryland have been instructed not to go on land where a "no trespassing" sign is posted and to ask residents' permission before walking around the property. Each team member will have a company identification card and a copy of a letter from the county explaining the purpose of the survey.

"The letter we wrote explains what we are doing, and hopefully, we will get their cooperation and be able to survey the house," Ocel said.

If no one is home, team members will leave a copy of the letter at the door with a request to respond by phone, he said.

Ocel said he and his staff will select 100 of the buildings surveyed for a more detailed report that will include photographs and drawings. The survey results will be public.

Ocel said he expects the $107,000 project to be completed by the end of August.