My mistake, I didn't realize the benefit of watering your foundation until I did some research! Learning something new every day. Vegetation determines two advanced settings, crop coefficient and root zone depth, and these are both customizable. Therefore, we can just work on tailoring those to the foundation, and basically disregard the actual vegetation selection.
How were you previously watering your foundation before Rachio? I'm trying to determine how deeply you would want to water this each time... this would drive how we set your root zone depth. For crop coefficient, I would crank that way way down (maybe even 0%). Crop coefficient determines how much water is "consumed" by your vegetation each day. Since there's no vegetation here, it's consuming nothing! Let me know what you think.