San Luis Obispo, California keeps its sign rules in Chapter 15.40 of the Municipal Code. The chapter works in layers: some signs need no permit, each sign type has its own size rule, and every zone has a cap on the total. This guide takes one made-up storefront in the Downtown Commercial (C-D) zone through all three layers and then through the permit. We read every section cited here on September 28, 2026.
The storefront
Everything about this storefront is invented. It is a ground-floor tenant space with a public entrance, 25 feet of frontage, an average height of 18 feet and 80 square feet of window glass. The owner wants a wall sign, window lettering, a blade sign over the sidewalk and a small hours-of-operation plaque by the door.
Layer 1: what doesn't count
Section 15.40.200 lists signs that need no sign permit, and says they “shall not be included in the determination of type, number, or area of signs allowed on a given property.” One entry covers the plaque: “Signs with an aggregate area not to exceed three square feet and located within five feet of an entrance to a building.” So a two-square-foot hours plaque beside the door is outside every count below. The same section warns that exempt signs may still need a building or encroachment permit.
Window displays set well back from the glass also drop out. Under section 15.40.470(B), window signs are those “located within thirty-six inches of the face of a window,” and displays more than thirty-six inches back “are not considered signs.”
Layer 2: each sign's own limit
| Sign | Rule | For this storefront |
|---|---|---|
| Wall sign | Lesser of 100 sq ft or 15% of the building face; section 15.40.470(A)(2) figures the face as frontage × average height | 25 × 18 = 450 sq ft face; 15% = 67.5 sq ft |
| Window signs | Lesser of 24 sq ft or 15% of the window area | 15% of 80 = 12 sq ft, if the city reads “window area” as all the storefront glass |
| Projecting (blade) sign | 12 sq ft in the C-D zone; one per tenant space; on a facade with a public entrance | 12 sq ft, one sign |
Section 15.40.470 sets that frontage-times-height shortcut. The definitions in section 15.40.1000 separately describe a “building face” as “the whole of a building visible in an elevation view, excluding sloped roof surfaces.” On an irregular elevation, ask the city which measure it applies.
The blade sign also has to clear the sidewalk. Section 15.40.440 requires at least eight feet between the lowest point of the sign and the grade below, at least two feet from the curb line, and a projection over a public sidewalk of no more than “two-thirds the width of the sidewalk or six feet, whichever is less.” On an invented 7.5-foot sidewalk, two-thirds is 5 feet, so the sign and its bracket can reach out 5 feet. Under section 15.40.470(D)(1), projecting signs must also be at least ten feet from other projecting signs on the same property, and separated by ten feet from projecting signs on adjacent properties or tenant spaces.
Downtown limits freestanding signs. Pole signs and multi-tenant signs are not allowed in the C-D zone, and a monument sign there is limited to twelve square feet and four feet tall.
Layer 3: the zone's total
Section 15.40.460 caps what a premises can have in total, and says the per-type standards cannot push past it: “In no case may the maximum number or size of signs, or their illumination levels, exceed the standards provided by this section, unless approved through a sign program or exception” (as provided in sections 15.40.485 and 15.40.600). For the C-D zone the table allows four signs per premises and 200 square feet of cumulative sign area.
If our owner uses a 60-square-foot wall sign, the full 12 square feet of window lettering and a 12-square-foot blade sign, then counting the window lettering as one sign, that is three signs and 84 square feet. The plaque does not count. The catch is the word “premises.” Section 15.40.1000 defines it as “a lot or series of lots under common ownership and/or developed together as a single development site, regardless of how many uses occupy the site.” If this storefront is the only tenant on its site, it is under both caps with room for one more sign. In a multi-tenant building, the other tenants' signs count toward the same four signs and 200 square feet.
Lighting and mounting
Section 15.40.470 says: “Internally illuminated cabinet signs are prohibited in the downtown commercial district.” It gives examples of allowed internally illuminated signs, including “backlighting, halo, or neon lit letters or emblems, channel letters, or logos.” It also requires all wall signs, in any zone, to use a direct or flush mount “without exposed wiring, raceways, or other stabilizing devices or mounts including backer mounts,” and it advises that on masonry, attachments “should be embedded into the mortar, not the brick or stone.” That last point belongs on the installer's work order, not just the permit drawing.
The permit path
- A permit is required for any sign that isn't exempt: “No sign shall be constructed, maintained, displayed or altered without a sign permit” (15.40.500).
- Straightforward applications have a forwarding deadline. For a complete application that needs no architectural review or other permits, the director must send it to the chief building official for issuance “within fifteen working days” (15.40.530). That deadline covers the hand-off, not the permit itself.
- Architectural review is a separate filing. When the architectural review commission has to review a sign, it takes its own application and fees (15.40.520).
- Multi-tenant buildings may already have a sign program. Sign programs “may supersede” the district standards in section 15.40.460 and the sign-type standards in section 15.40.470, and a program must be approved, with all appeal periods expired, before anyone files a sign permit under it (15.40.485). Ask the landlord for it first.
- Exceptions must meet all three findings. Unusual circumstances that make strict compliance impractical; consistency with the chapter's purpose, with no adequate allowed alternative; and superior design that avoids clutter and oversized signage (15.40.610). An exception takes its own application and fees, and must be approved before the sign permit is issued (15.40.600).
Before you order anything
- Confirm the zone. The C-D numbers above do not carry over to other zones.
- Ask whether a sign program already governs the building.
- Measure frontage, average height, window area and sidewalk width, and keep the drawing with the math.
- List every existing sign on the premises, including other tenants' signs, because the 200-square-foot and four-sign caps count them.
- Specify the lighting method and mounting details that section 15.40.470 allows downtown.
The window, wall-formula and awning rules used here are also worked in our glossary entries on the wall-sign formula and awning and projecting signs, and in the window coverage guide.
This is general research guidance, not a permit decision for any property. The storefront is invented. The code shown is current through Ordinance 1757, passed June 2, 2026, per the city's code host; the city clerk has the official version, and the city controls current requirements.