Sign allowances get the attention, but the measuring rule decides how much of an allowance a design uses up. Two codes can both allow a 40 square foot wall sign and still treat the same drawing differently, because they draw the line around it in different places. To show how much that matters, we took the fictional wall-sign face from our Austin case file and measured it under three codes we read on September 28, 2026: the City of Austin, unincorporated Loudoun County in Virginia, and the Village of Addison in Illinois.
The test shape
The face is an L: an upper bar 6 feet wide and 2 feet high, joined along its edge to a lower-left block 2 feet wide and 2 feet high. The smallest rectangle around it is 6 by 4 feet, or 24 square feet. The shape itself covers 16 square feet. Every dimension is invented for this exercise, and nothing below is a finding about a real sign.
Austin: the smaller of two enclosures
Austin's Land Development Code section 25-10-5 measures a wall sign as the lesser of two areas: the smallest rectangle that encloses the sign face, or the smallest area of not more than three contiguous rectangles that enclose different sections of the sign. For the L, the first option gives 24 square feet and the second gives 16, so the sign measures 16. Subsection (D) adds that sign area “includes a sign apron or similar feature and an area displaying a sign company name or symbol,” and excludes a supporting structure, pole cover, or landscape feature unless it is used to convey a message. The online section history ends with Ordinance 20170817-072.
Loudoun County: a continuous perimeter and the rule of 8
In unincorporated Loudoun County, section 8.11 of Chapter 8 of the Zoning Ordinance starts with a general rule: “The sign area is within a continuous perimeter enclosing the limits of a sign.” For irregular shapes, subsection F applies what the county calls the “rule of 8”: the sign is outlined with no more than eight connecting lines, and the area is “the area of two rectangles formed by 8 connecting lines.” The L has six sides, so its outline fits inside the limit and it breaks into exactly two rectangles. It measures 16 square feet.
One caution about that chapter. Several measurement figures in the county's PDF, including the irregular-shape figure, are labeled “new figure will replace this one.” Measure from the text, and check whether the county has published the replacement figures before you rely on a drawing.
Addison: the straight-line perimeter
The Village of Addison defines wall-sign area in section 27-104 of Chapter 27 of the Village Code: the area lies “within a single, continuous perimeter composed of any straight line geometric fixture which encloses the extreme limits of the advertising message.” A straight-line perimeter can follow the L exactly, so the bare face measures 16 square feet here too.
Where the three codes split: add a background panel
Now mount the same L-shaped copy on a painted 6 by 4 foot panel that sets it off from the wall. Nothing about the lettering changes. The measurement does.
Addison answers directly. The same definition says “the outside dimension of the frame, box or background board shall be used to determine area.” The panel sets the area: 24 square feet.
Loudoun County reaches the same place by a different route. Section 8.11.A.2 says sign area “includes any frame or other material or color that forms an integral part of the display or is used to differentiate the sign from the sign background against which it is placed.” A panel painted to set the copy apart from the wall reads as that kind of material, so the perimeter would follow the panel: 24 square feet. That is our reading of the text; county staff make the call on a real application.
Austin is the one to ask about. Section 25-10-5 does not name background boards or panels for wall signs. It measures the sign face, and subsection (D) pulls in “a sign apron or similar feature.” Whether a plain panel is part of the face or a feature similar to an apron is a question for the city's sign reviewers, not one to settle on a drawing. If they count it, the panel is a single 6 by 4 rectangle and the area is 24. If they do not, it stays at 16. Write down who answered and when.
Individual letters are a third case
Addison has a separate rule for signs made of individual letters, such as channel letters mounted directly on a wall. Each word is measured as a rectangle, the height of the tallest letter times the length of the word, and the word rectangles are added together. The code never mentions the gaps between words. Because the area is built word by word, it appears the gaps are left out, but that is our reading, so confirm it with the village. The text does not say whether “tallest letter” means the tallest in each word or in the whole sign; if letter heights vary, ask the village.
Neither Austin's section 25-10-5 nor Loudoun's section 8.11 has a word-by-word rule. Under Austin's “contiguous rectangles” language and Loudoun's “continuous perimeter,” how the gaps between separated words are treated is not spelled out in the text we read. On a spaced-out letter sign in either place, that is worth confirming before the drawings are final, because the gap can be a large share of the enclosed area.
Freestanding signs split further
The three codes also point different ways on what a freestanding sign includes.
- Loudoun County measures a ground sign with “a rectangle enclosing the area of the sign face and structure” (section 8.11.B.1.b). For a pole sign, the rectangle encloses the face and background elements but not the poles (8.11.B.1.a). Where lettering appears back to back, on opposite sides of a sign, only one display face is counted (8.11.B.1.d). The same section's general rule, 8.11.A.3, excludes “the structural supports or uprights on which the sign is placed,” so ask how the county treats a monument base before counting it.
- Addison adds up the area enclosed by each cabinet's perimeter when a freestanding sign has one or two cabinets, and uses a single rectangle around all of them when it has more than two. Pole covers and supports are left out when they carry no advertising copy. Only the largest face of a double-faced sign counts, and a sign on a freestanding monument wall is measured like a wall sign.
- Austin leaves out a supporting structure, pole cover, or landscape feature unless it is used to convey a message, under subsection (D). Under subsection (B), a sign with two faces, only one of which is visible from any point, is measured using one face.
So for a monument sign on a masonry base, Loudoun's ground-sign wording points toward counting the base and Austin's points away from it, unless the base carries a message. Addison's answer depends on whether the face is a cabinet on a structure or copy on a monument wall. On a tight allowance, get the base question answered before fabrication.
What we record for each measurement
| Code | Section | Bare L face | L face on 6 × 4 panel |
|---|---|---|---|
| City of Austin, Texas | § 25-10-5(A), (D) | 16 sq ft | 16 or 24 sq ft; ask city staff |
| Unincorporated Loudoun County, Virginia | § 8.11.A, 8.11.F | 16 sq ft | 24 sq ft (our reading; confirm with county staff) |
| Village of Addison, Illinois | § 27-104, “Sign, area of” (2) | 16 sq ft | 24 sq ft |
A 16 against 24 difference is half again as much area. On a building where the allowance is tight, that decides whether the panel design fits or the copy has to shrink. Record the measurement method next to the allowance, with the section number and the drawing it was applied to.
Before any of this applies, confirm which government writes the rules for the address. For these two jurisdictions, see which sign code covers a Loudoun County address and confirming the Addison village line. For the general arithmetic, our wall sign area guide covers the common methods, and the authority and source worksheet keeps the record.
This is a worked example on an invented drawing, not a measurement or permit decision for any real sign. Sources were read on September 28, 2026, and each code can be amended; the governing jurisdiction controls how its rules apply to a specific design.