An appraisal of the real estate assets of Federal Realty Investment Trust of Chevy Chase has increased the fair market value of those assets to $108.5 million as of Dec. 31, 1980, or $49.8 million more than the net book value (original cost less depreciation) of the assets that were reported in the trust's year-end financial statements.

The appraisal was performed by Landauer Associates Inc., whose staff physically inspected 11 shopping centers and two apartment developments.

Combined with the trust's shareholders' equity of $20.2 million, the unrealized appreciation of $49.8 million brings Federal Realty's appraised equity value to $70 million, on $33.65 on a fully diluted, per-share basis compared to a book value of $10.29.

"The trustees believe this appraisal provides meaningful information to our shareholders and the investing public," said President Steven J. Guttman. "Federal Realty's intensive property management techniques have clearly added value to the trust's properties. Of course, the appraisals should be evaluated with the understanding that normal selling expenses associated with real estate transactions are excluded, and that future sales may be at prices which vary from the individual estimates."

Federal Realty owns 19 shopping centers with a total leasable area of 2.86 million square feet and five apartment complexes in Maryland and Virginia with 1,074 units.