Setbacks are measured from the building to the property line.
Note however that the Land Development Code (LDC) allows for up to a 5 foot credit if the property line goes into an adjacent waterway. For example, if the property line was 10’ out into the water (beyond the seawall) then you can measure the 25’ required waterbody setback starting 5’ into the water.
If the property line is inside the seawall, then the measurement is from the property line.
If you have further questions regarding setbacks, zoning, and other Land Development Code issues, please fee free to reach out to our planning section staff at firstname.lastname@example.org.