Place your construction adhesive into a caulk gun.
Apply quarter-sized amounts of construction adhesive every 1 to 2 inches along the top of the mirror.
Press the framing onto the mirror. Use a level to make sure the framing is straight.
Place tape around the framing to hold it in place as the constriction adhesive dries. Apply tape every 2 to 4 inches. Let the construction adhesive dry according to the manufacturer’s directions. Remove the tape once the adhesive is dry.
Apply framing around the rest of the mirror, if desired, following the same steps.