Thornton, Colorado Sign Code & Sign Permit Guide
Wall, monument, and freestanding sign limits for Thornton by zoning district — cited to the exact code section, with the sign permit process. Every number is checked against the published code text before it ships.
Nonresidential (BP, CC-L, CI, EB, EC-L, EO, ES, ETD, GC, I-L, NC, RC)
Zones like BP
Thornton Reenacted Development Code §§18-736–18-757 (Divisions 3–5, Attached/Freestanding/Electronic Signs), effective Sept 1, 2025. Covers Business Park, City Center Legacy, Civic Institutional, Eastlake Business/Service/Office/TOD, Employment Center Legacy, General Commercial, Industrial Legacy, Neighborhood Commercial, and Regional Commercial. AG (Agricultural) is grouped with residential by default (see the residential family) but gets nonresidential-style Canopy/Monument/Pole/Light-pole-banner allowances — see those cards' notes.
Flat caps by zone-district group, not a frontage formula: Thornton sets a flat area/height/count cap per sign type and zone-district group (2–5 groups depending on the sign type) rather than one linear-foot rate — wall-sign area for high-rise buildings additionally scales with story count. Match your sign type and zone to the right card above; there's no frontage calculator input here.
Wall signs
§18-741 · Table 18-741.1| Low-rise (1–3 stories) | Unlimited number · greater of 60 sq ft or 8% of the largest building elevation's area |
|---|---|
| High-rise (4+ stories) | Unlimited on the 1st floor + 2 above (max 1/elevation) · 300 sq ft (4–5 stories) · 325 sq ft (6 stories) · 350 sq ft (7 stories) · 400 sq ft (8–10 stories) · 575 sq ft (11–14 stories) · 550 sq ft (15+ stories) |
Max 1,000 sq ft on any one elevation, 2,000 sq ft across all elevations — both waived for large developments with 300,000+ sq ft of retail on a single 50+ acre lot fronting I-25/E-470. Total wall + projecting signs combined can't exceed the wall-sign maximum. AG is NOT included here (grouped with residential — no wall signs).
Canopy signs
§18-737 · Table 18-737.1| Nonresidential (including AG) | Any number, total ≤ 60 sq ft · height/setback controlled by the canopy structure · concealed illumination or neon |
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One of the few signTypes where AG is explicitly grouped WITH nonresidential rather than residential.
Cylinder signs
§18-738 · Table 18-738.1| Nonresidential only (AG = none) | 1 sign · 12 sq ft · 10 ft height · projects ≤ 15 inches from the wall · may rotate up to 50 revolutions per minute · concealed illumination |
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Projecting signs
§18-739 · Table 18-739.1 · Table 18-730.1| NC, GC, RC, CC-L, EC-L, EB, ES, EO, ETD | 1 per building user/tenant · total ≤ 50% of the wall-sign allowance alone, or 100% combined with wall signs · height ≤ 1st floor elevation · min 7 ft clearance above grade |
|---|---|
| BP, CI, I-L (and all residential/AG) | Not allowed |
§18-739 itself only splits Residential-and-AG vs. Nonresidential; which specific nonresidential zones actually get projecting signs comes from the Permitted Signs Chart (Table 18-730.1) — Business Park, Civic Institutional, and Industrial Legacy are excluded even though they're nonresidential.
Under-canopy signs
§18-740 · Table 18-740.1 · Table 18-730.1| NC, GC, RC, CC-L, EB, ES, EO, ETD | 2 per building user/tenant · 4 sq ft · min 7 ft clearance from the bottom edge · concealed illumination |
|---|---|
| BP, CI, EC-L, I-L (and all residential/AG) | Not allowed |
Same source split as Projecting signs — the Permitted Signs Chart (Table 18-730.1) excludes Business Park, Civic Institutional, Employment Center Legacy, and Industrial Legacy even though they're nonresidential.
Monument signs
§18-750 · Table 18-750.1| EB, ES, EO | 1 per street frontage over 90 lf · 40 sq ft · 8 ft height |
|---|---|
| ETD | 1 per street frontage over 90 lf · 60 sq ft · 8 ft height |
| AG, NC, GC, MU, CI, TOD | 1 per street frontage over 90 lf · 60 sq ft · 30 ft or building height, whichever less |
| RC, BP, CC-L, EC-L, I-L | 1 per street frontage over 90 lf · 100 sq ft · 30 ft or building height, whichever less |
Bonus signage near I-25/E-470 (§18-747(3)) may be consolidated into one monument sign, raising height to 50 ft for large developments. Large developments with an internal public-access roadway get one additional 40 sq ft / 8 ft sign per main building.
Pole signs
§18-751 · Table 18-751.1| AG, NC, GC, CI, MU, BP | 1 per zone lot with ≥90 lf of street frontage · 40 sq ft · 30 ft or building height, whichever less |
|---|---|
| RC, BP, EB, I-L | 1 per zone lot with ≥90 lf of street frontage · 80 sq ft · 30 ft or building height, whichever less |
Not allowed in residential zones at all. BP appears in both the 40 sq ft and 80 sq ft columns in the source table as written. The Permitted Signs Chart (Table 18-730.2) additionally disagrees with this table in three places — see Gotchas: it marks EB as NOT permitted (contradicting EB's own 80 sq ft listing here), and marks City Center Legacy and Employment Center Legacy as permitted even though §18-751 sets no size for either.
Billboard signs
§18-748 · Table 18-748.1 · Table 18-730.2| Industrial Legacy (I-L) only | Any number, ≥600 ft from any other sign and ≥1,000 ft from another billboard · 300 sq ft · 25 ft height (min 8 ft clearance within 1,000 ft of an intersection) · 25 ft setback + 300 ft from intersecting rights-of-way |
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§18-748's own table just says "Nonresidential Zone Districts" for sizing; the Permitted Signs Chart (Table 18-730.2) is the actual gate on WHICH nonresidential zone, and it permits billboards in Industrial Legacy only — every other nonresidential district (including General/Regional Commercial) is N. Off-site freestanding signs only (no attached billboards); undeveloped property only, removed once development begins; max 2 structural supports.
Light pole banners
§18-749 · Table 18-749.1| Nonresidential (including AG) | 2 banners per 100 lf of street frontage (2 more per additional 100 ft increment) · max 2 per light pole · 15 sq ft · mounted below the light arm · min 7 ft clearance |
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Electronic signs
§18-757 · Table 18-757.1| All zone districts | 1 per zone lot (+1 for large developments) · 50% of the monument allowance, or 30 sq ft if wall-mounted · ≤ 300 NITs dusk-to-dawn · min 5 sec message hold · dissolve/fade transitions only, < 1 sec |
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Not allowed as pole signs or billboards. Residential/AG and NC/EB/ES/EO/ETD zones need a 1-acre-or-larger lot; other nonresidential zones instead need I-25/E-470/arterial/collector street adjacency.
Special event signs (temporary, permit required)
§18-763 · Table 18-763.1| Nonresidential | 6 permits/calendar year, ≤ 15 consecutive days each · 60–400 sq ft depending on the host use's floor area (<25,000 sf → 60 sq ft; 25,000–100,000 sf → 150 sq ft; 100,000+ sf → 400 sq ft) · 20 ft max height (freestanding/feather flags) · 10 ft setback |
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Includes banners, freestanding signs, feather flags, balloons, air dancers, pendant strands, and inflatables — allowed IN ADDITION to other temporary signs on the property.
Temporary signs (no permit required)
§18-764 · Table 18-764.1| NC, MU, CI, EC-L, EB, ES, EO, ETD | 150 sq ft max per developed lot (based on the use's floor area, up to 150 sq ft) · 150 sq ft per undeveloped lot · 10 ft max height |
|---|---|
| GC, RC, BP, CC-L, TOD, I-L | up to 230 sq ft max per developed lot (based on floor area) · 250 sq ft per undeveloped lot · 20 ft max height |
One sign may display up to 180 days; the rest are capped at 30 days on a developed lot (no limit on an undeveloped lot). Setback = 5 ft or the sign's height (whichever greater) + 25 ft from intersections.
See the exact numbers
Height, setback, area, count, and lighting limits for Nonresidential (BP, CC-L, CI, EB, EC-L, EO, ES, ETD, GC, I-L, NC, RC) — cited to the code section, ready to quote from.
Get notified at launch- Pole signs in Eastlake Business, City Center Legacy, and Employment Center Legacy: Thornton's own two governing tables (the Table 18-730.2 permission chart and §18-751's size table) disagree with each other for these three districts — confirm with the city before quoting; see the Pole signs card note.
- PD-L and MC-L parcels route by the site's actual use (residential vs. nonresidential), not by their flat zone code (§18-711(m)(1)) — confirm with the city before quoting a Planned Development Legacy or Mineral Conservation Legacy parcel.
Residential and AG (AG, RE, SFD-L, RM, RH, MH-L, ER)
Zones like AG
Thornton Reenacted Development Code §§18-736–18-764, effective Sept 1, 2025. Covers Agricultural, Residential Estate, Single-Family Detached Legacy, Residential Mid/High Density, Manufactured Home Legacy, and Eastlake Residential. Most attached-sign types (cylinder, projecting, under-canopy, wall) and billboards are NOT permitted in these zones at all — only Monument, Light pole banner (AG only, not other residential), Canopy (AG only), Electronic (1-acre-minimum lot), and temporary/special-event signs have real residential allowances.
Flat caps by zone-district group, not a frontage formula: Residential zones have no attached-sign or billboard allowance; the real numbers are monument, electronic, temporary, and special-event signs, plus a small canopy/light-pole-banner allowance for AG only. Match your sign type to the right card above.
Monument signs
§18-750 · Table 18-750.1| Residential zone districts | 2 signs allowed (per zone lot street frontage over 90 lf, plus additional per §18-747(4)) · 42 sq ft · 6 ft height |
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Should be located within a planted landscape area providing ground definition, similar in character to the surrounding area (§18-750(b)).
Canopy signs (AG only)
§18-737 · Table 18-737.1| AG District | Any number, total ≤ 60 sq ft · height/setback controlled by the canopy structure |
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Every other residential zone gets NONE — Table 18-737.1 explicitly groups AG with nonresidential for canopy signs specifically.
Light pole banners (AG only)
§18-749 · Table 18-749.1| AG District | 2 banners per 100 lf of street frontage · 15 sq ft · mounted below the light arm · min 7 ft clearance |
|---|
Every other residential zone gets NONE — Table 18-749.1 groups AG with nonresidential ("including AG District").
Electronic signs
§18-757 · Table 18-757.1| All residential zones + AG | 1 per zone lot (+1 for large developments) · 50% of the monument allowance, or 30 sq ft if wall-mounted · lot must be 1 acre or larger · ≤ 300 NITs dusk-to-dawn · min 5 sec message hold |
|---|
Special event signs (temporary, permit required)
§18-763 · Table 18-763.1| Residential and AG | 4 permits/calendar year, ≤ 15 consecutive days each · 60–400 sq ft depending on the host use's floor area · 20 ft max height (freestanding/feather flags) · 10 ft setback |
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Temporary signs (no permit required)
§18-764 · Table 18-764.1| Lot under 1 acre | 72 sq ft max per developed lot · 120 sq ft per undeveloped lot · 6 ft max height |
|---|---|
| Lot 1 acre or larger | 100 sq ft max per developed lot · 120 sq ft per undeveloped lot · 10 ft max height |
One sign may display up to 180 days on a developed lot; the rest are capped at 30 days (no limit on an undeveloped lot).
See the exact numbers
Height, setback, area, count, and lighting limits for Residential and AG (AG, RE, SFD-L, RM, RH, MH-L, ER) — cited to the code section, ready to quote from.
Get notified at launch- Wall signs in AG: Thornton's own two governing tables disagree — the Table 18-730.1 permission chart marks Wall signs permitted in Agricultural, but §18-741's own Wall sign table caps AG at None. This reference follows §18-741 (no wall sign card for AG); confirm with the city before treating that as final.
Sign permits in Thornton
City of Thornton Building Department — 303-538-7250; Planning Department 303-538-7295
Thornton sign code FAQ
What is the sign code for Thornton, Colorado?
Thornton's sign regulations are set by Ch. 18 Art. XI Sign Standards (PDF pp. 652–703) · thorntonco.gov, and vary by zoning district. Sightline tracks 2 verified zone families for Thornton below, each with wall, freestanding, and other sign-type limits cited to the exact section.
Do I need a permit for a sign in Thornton?
In nearly every Colorado municipality, including Thornton, permanent signs — wall signs, channel letters, cabinets, monument signs — require a sign permit. Thornton's permit process is linked below. Always confirm with the authority having jurisdiction before finalizing a design.
Look up an exact address in Thornton
Get the live zoning district and the sign limits that apply to a specific parcel, with a frontage calculator and a permit-ready citation.
Get notified at launch