In the last three years, Falls Church residential property values have increased approximately 37 per cent while the value of commercial parcels have appreciated between 6 and 20 per cent, according to findings of the city's reassessment office.

Property owners in the city can expect to receive news on the increased value of their own holdings this week. Several thousand real estate assessment notices were scheduled to be mailed out yesterday, according City Assessor William De Lanoy.

De Lanoy said his findings are based on estimates of fair market value of all city property as of Jan. 1, 1977, and represent increases in value since the city's last reassessment in 1974. Although the notices themselves are not tax bills, De Lonay said they will be the basis for real estate tax bills due at the end of 1978 and 1979.

With the notices, the city also launches a new assessment procedure, De Lanoy said. Beginning with tax bills for 1978, which will be due next December, property will be assessed for tax purposes at 100 per cent of fair market value and reassessments will be done on all of the approximately 3,500 properties in the city every two years. In the past, the city has reassessed property every four years and based tax bills on 50 per cent of fair market value.

As part of the reassessment, De Lanoy said all properties were externally inspected and "several hundred" were viewed from the inside.

"We went inside if we had some reason to think the information (about the structure) was not correct. If we see two bathroom vents out of the roof of the house and our information indicates there is only one bathroom, chances are one has been added," he said.

Listings of all property values as a result of the reassessment will be available in early December at the city library, community center and city hall, De Lanoy said.Individuals wanting to appeal the assessments have from Dec. 15 to Jan. 13 to schedule a hearing with the assessments office, De Lanoy said.