Sign height is measured from a starting point up to a top point, and the code picks both. On sloped ground the same sign can measure two different heights depending on where you start, so a maximum number means nothing until you know its starting point.
How one real code handles it
For freestanding signs in its expressway corridor sign district, Austin, Texas gives two starting points and lets the taller answer govern, in section 25-10-123(B)(3) of its Land Development Code:
“The sign height may not exceed the greater of: (a) 35 feet above frontage street pavement grade; or (b) 20 feet above grade at the base of the sign.”
Here is what that does on two made-up lots:
| Lot | Top allowed by (a) | Top allowed by (b) | Governing height above the sign's base |
|---|---|---|---|
| Sign base 10 ft below the frontage street | 45 ft above the base | 20 ft above the base | 45 ft, from rule (a) |
| Sign base 20 ft above the frontage street | 15 ft above the base | 20 ft above the base | 20 ft, from rule (b) |
A sign sitting below the road gets extra height; one sitting above the road is held to 20 feet from its own base. The rule applies only in that sign district, so check the district first. (We read it on September 28, 2026. The lot elevations are invented.)
Before drawing the maximum
Confirm the sign's category, the district, the starting point (existing grade, finished grade, an average, the road, or another datum), and whether caps, supports or decorative tops count. Use the starting point the code names. Only take whichever one gives more height when the code says so, as Austin's rule does. Do not assume moving the sign back earns extra height unless the code says so.
Use the height-measurement guide for the drawing checklist and the classification guide when the sign type is unclear.