Zoning, building permits and septic rules in Longmont, Colorado

At a glance

Zoning

Longmont zones land inside city limits under its Land Development Code¹

Building permit

Required, with the standard residential exemptions narrowed³

Building code

Adopted with local amendments⁵

Septic

Boulder County Public Health regulates onsite systems countywide⁴

Camping on private property

Allowed only with the owner's permission, and not in a dwelling⁶

Minimum lot, R-RU

1 acre and 150 feet wide⁷

Floodplain

Special standards in mapped flood hazard areas⁸

Who to call

Contact details are copied from each office’s official page and were checked against it on October 16, 2026.

Does Longmont, Colorado have zoning, and what does it mean for lots and setbacks?

Yes. Longmont zones land inside city limits through Chapter 15.03 of its Land Development Code¹. Residential districts include R-RU, R-SF, R-MN, R-MF and R-MH, and nonresidential districts include N-PE, N-AG and N-PF⁹. Rules differ by district, so find the parcel's district on the city's interactive planning map or ask Planning and Development Services¹⁰.

In the rural residential R-RU district, the minimum lot is 1 acre and 150 feet wide⁷, with 20-foot front and rear yards and 10-foot side yards¹¹. In R-SF, the minimum lot is 5,000 square feet¹², with a 15-foot front yard for a dwelling and 5-foot side yards¹³. In the N-AG agricultural district, the minimum lot is 1 acre¹⁴. Height caps are 35 feet in R-RU and R-SF¹⁵¹⁶ and 45 feet in N-AG¹⁷. Accessory structures follow separate standards in section 15.04.040¹¹.

Do you need a building permit in Longmont, Colorado, and who issues it?

Longmont's own Building Services department issues building permits for work inside city limits, not Boulder County². The city adopted the International Residential Code with local amendments, and the amendments shrink the list of exempt work: the exemption for one-story detached sheds and playhouses is limited by floor area, and two other exemptions are deleted³⁵.

Building Services states that the city adopted the 2024 international codes, effective July 1, 2026². Permit applications go through the city's online application system, and the city notes its Accela portal may have technical difficulties after recent software updates, so call 303-651-8332 if the portal fails². We could not confirm the city's permit fee schedule, owner-builder rules or certificate of occupancy process, so ask Building Services before you budget.

How do septic permits work inside Longmont?

Septic is not a city function. Boulder County Public Health regulations govern all onsite wastewater treatment systems in Boulder County, and that includes systems on lots with a Longmont address¹⁸⁴. Colorado law has every local board of health adopt detailed rules for these systems¹⁹, and an onsite system needs a permit from the local public health agency²⁰.

We could not confirm whether the city allows a septic system on a lot inside city limits or which parcels lack city sewer. Call the SepticSmart Program at 303-441-1564 and Longmont Building Services before you assume a septic system is allowed on a particular parcel¹⁸. Wells are separate: every new well that diverts groundwater needs a state well permit²¹.

Can you live in an RV or tiny home in Longmont?

Camping on private property inside Longmont is unlawful unless the owner or person responsible for the property gives permission, the rule does not apply to any dwelling in the city, and camping on city property requires a permit⁶. Anyone sleeping outside a dwelling must also have access to a bathroom or portable toilet on the property⁶. We could not confirm whether Longmont's zoning allows living in an RV long term, so ask Planning and Development Services¹⁰.

For tiny homes, Colorado's Division of Housing says tiny homes it approves are fit for long term living, but the unit must also satisfy local zoning²². Longmont's own tiny home rules were not confirmed. Inside city limits, the county's rules for unincorporated land do not apply; see the Boulder County page for land outside the city.

Building a home in Longmont: the steps, in order

1. Identify the parcel's zoning district and confirm lot size, setbacks and height with Planning and Development Services¹⁰.
2. Check the city's floodplain standards if the parcel is in a mapped flood hazard area; where base flood elevation data exists, the lowest floor must be elevated one foot above it⁸.
3. Confirm water and sewer service with the city, and call Boulder County Public Health if any septic system is proposed¹⁸.
4. Apply for the building permit through Building Services' online application system².
5. Schedule inspections through the city's portal or main office².

What stays with Boulder County, and what to check before you buy in Longmont?

Septic permits stay with Boulder County Public Health for every address in the county, city or not⁴. Boulder County's Land Use Code and building permits apply to unincorporated land, not inside city limits²³.

Before you buy, check the flood hazard map, since recreational vehicles in certain flood zones must be on site fewer than 180 consecutive days unless they meet permit and elevation rules⁸. Boulder County's effective property tax rate is 0.5%²⁴. Colorado also requires an access permit for direct access to a state highway²⁵.

Watch-outs

• The city's zoning use table for RVs, tiny homes, manufactured homes and accessory dwelling units was not confirmed, so ask Planning and Development Services at 303-651-8330 before you rely on any of them¹⁰.
• Longmont's building code amendments narrow the standard residential permit exemptions, so confirm that a shed, deck or fence is exempt before you build³.
• Boulder County's rules for unincorporated land, including its 14-day camping limit, do not apply inside Longmont city limits²⁶.

Sources

1. Longmont Code Sec. 15.03.020 Residential districts (Longmont), quoted and re-checked
2. City of Longmont Building Services (longmontcolorado.gov)
3. Longmont Code Sec. 16.06.060 R105.2 amended (Longmont), quoted and re-checked
4. OWTS Permits and Fees - Boulder County, quoted and re-checked
5. Longmont Code Sec. 16.06.060 R105.2 amended (Longmont), quoted and re-checked
6. Longmont Code Sec. 10.24.120 Camping (Longmont), quoted and re-checked
7. Longmont Code Sec. 15.03.020 Residential districts (Longmont), quoted and re-checked
8. Longmont Code Sec. 20.20.020 Specific standards (Longmont), quoted and re-checked
9. Longmont Code Sec. 15.03.020 Residential districts (Longmont), quoted and re-checked
10. City of Longmont Planning and Development Services (longmontcolorado.gov)
11. Longmont Code Sec. 15.03.020 Residential districts (Longmont), quoted and re-checked
12. Longmont Code Sec. 15.03.020 Residential districts (Longmont), quoted and re-checked
13. Longmont Code Sec. 15.03.020 Residential districts (Longmont), quoted and re-checked
14. Longmont Code Sec. 15.03.040 Nonresidential districts (Longmont), quoted and re-checked
15. Longmont Code Sec. 15.03.020 Residential districts (Longmont), quoted and re-checked
16. Longmont Code Sec. 15.03.020 Residential districts (Longmont), quoted and re-checked
17. Longmont Code Sec. 15.03.040 Nonresidential districts (Longmont), quoted and re-checked
18. Boulder County Public Health SepticSmart Program (bouldercounty.gov)
19. Title 25 - Public Health and Environment - Colorado Revised Statutes 2024 (Colorado statewide rule), quoted and re-checked
20. Title 25 - Public Health and Environment - Colorado Revised Statutes 2024 (Colorado statewide rule), quoted and re-checked
21. Water Administration (Colorado statewide rule), quoted and re-checked
22. Consumers of Manufactured Homes and Tiny Homes - HUD (Colorado statewide rule), quoted and re-checked
23. Land Use Code - Boulder County, quoted and re-checked
24. Effective property tax rate: Bolthole Index county data
25. Access Permits | Frequently Asked Questions (Colorado statewide rule), quoted and re-checked
26. Planning FAQ - Boulder County, quoted and re-checked

Written October 16, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.