Fairfax County School Supt. S. John Davis Thursday night recommended asking the voters in June to approve a $19.5 million school bond issue.

If approved at referendum on primary election day, June 14, the bond sale would finance construction of two new elementary schools, in Herndon and Reston, and improvements to 16 other county schools.

Davis' recomendation must have the approval of the school board, the county Board of Supervisors and the Circuit Court before a referendum can be scheduled.

County voters approved a $15.4 million bond issue last April, but had rejected bond issue proposals on two previous occasions.

School officials said the proposed $19.5 million issue is needed to alleviate overcrowding in the Herndon Reston area and to make needed repairs at older schools.

The bond issue would include $5.9 million for the new elementary schools in Herndon and Reston, $1 million to convert the Quander Road Elementary School to a special education center and build an addition at the Woodson Frost secondary school complex for another special education center, and $12.6 million for improvements and air conditioning at 14 school.

The bond issue approved at referendum last April was to finance construction of a high school in Reston and for renovation of two schools for the handicapped. Voters had rejected a $60 million proposal in 1974 and a $43.6 million school bond issue in 1975.

The board of supervisors sold bonds to the Virginia Public School Authority - something that did not require voter approval - to build the Terraset Elementary School in Reston after voters defeated the 1975 bond issue.

In other action Thursday night, the school board voted to send layoff notices to 169-full-time and 233 parttime teachers because it is unclear whether the school budget that will be approved by the supervisors will provide enough money to pay the teachers.

State law requires the school board to notify teachers by April 15 if their contracts are not to be renewed.

Last year, the board sent layoff notices too 300 teachers, but following approval of the school budget, all were rehired.

The board also deferred until next Thursday action on changes in personnel policies and practices as a result of the recent Virginia Supreme Court decision outlawing collective bargaining for public employees. Several hundred teachers crowded the school board meeting room and corridors Thursday night to protect changes in the personnel rules.