I am primarily a theory guy.
You will be aiming your high gain directional antennas vertically at each other with a common polarization of, for instance, east-west or north-south.
You will need to mount your antennas far enough away from the building to keep the building sufficiently out of the Fresnel zone of the antennas. This may be about five feet.
"For a .1 mile link using the 2.4 GHz 60% of the first fresnel zone at its widest point (middle of the path) is: 4.4 feet."
I hope this helps. Can you add your location to your forum profile? Thanks. /criss