Barndominiums in Colorado

Outside city limits: There is no single state rule. Whether a rural or unincorporated parcel needs a building permit, and which codes apply, is decided by the county (or the town, if the land is inside town limits). Where a local building department exists it issues and inspects the permit. Check with the county building or community development office before buying land or ordering a building.

Colorado has no statewide building code. Residential building codes are adopted locally by cities, towns and counties, so the edition (and whether any code applies at all) depends on the exact address. Most Colorado cities have adopted the 2018 International Building Code, according to the state housing agency, but rural counties set their own rules. Enforcement is by the local building department. The one statewide floor is on energy: when a jurisdiction adopts or updates any building code it must also adopt a current energy code (see the energy section). For a barndominium, the first call should be to the county or town building department for the parcel.

• The state housing agency's local-officials toolkit says building codes in Colorado are adopted municipally because the state does not have a statewide building code, and that most Colorado cities have adopted the 2018 International Building Code. source
• Under HB19-1260 (effective August 2, 2019), a Colorado jurisdiction that adopts or updates any building code must also adopt and enforce one of the three most recent editions of the International Energy Conservation Code. source
• The Colorado Energy Office keeps a map of building energy codes by jurisdiction, so a buyer can look up the energy code in force for a given city or county. source

Septic systems (called on-site wastewater treatment systems, or OWTS) are governed by the state's Regulation 43, but permits for systems of 2,000 gallons per day or less are issued by the county or local public health agency. Every local agency has adopted rules at least as strict as the state regulation, so details, fees and forms differ by county. Applications generally need a site and soil evaluation, a system design and a site plan, and some designs must be stamped by a Colorado-licensed professional engineer. The current version of Regulation 43 took effect June 15, 2025, and local agencies are updating their own rules to match. Fees below are examples from three counties and vary widely.

• The state health department says on-site wastewater systems are governed by Regulation 43; for flows of 2,000 gallons per day or less, permitting is done by local counties, and each local public health agency has adopted regulations at least as stringent as Regulation 43. Systems above 2,000 gallons per day go through the state's design review process. source
• The current version of Regulation 43 (5 CCR 1002-43) is effective June 15, 2025; it was adopted March 10, 2025 and published in the Colorado Register April 10, 2025. source
• Garfield County requires an application with a completed site and soil evaluation, a system design and a site plan, and says its OWTS regulations were updated May 28, 2026. source
• Mesa County's regulations require a permit before installing, altering, expanding or repairing a system, and require systems to be designed and stamped by a Colorado-licensed professional engineer approved by the department. source
• Larimer County's permit application states that engineer-designed systems may not be self-installed by the property owner, and that self-installing otherwise costs an additional fee. source
• Mesa County's rules say individuals installing or repairing systems on their own property for their own use are exempt from the systems-contractor licensing requirement. source

Colorado does not set one statewide residential energy code; the federal Department of Energy lists the state as home rule, with enforcement by each jurisdiction. State law sets a floor, though. Since 2019, a city or county that adopts or updates any building code must also adopt a current International Energy Conservation Code edition. HB22-1362 (signed June 2, 2022) tightened this: between July 1, 2023 and June 30, 2026, an updating jurisdiction had to adopt the 2021 or 2024 IECC plus the state's Model Electric Ready and Solar Ready Code. From July 1, 2026, a city or county that adopts or updates any building code must adopt the Colorado Model Low Energy and Carbon Code (based on the 2024 IECC) or something more stringent. A rural area that has not updated its codes may still be on an older edition, so check locally.

• The federal Department of Energy lists Colorado's residential energy code as home rule with jurisdictional enforcement, and says the state's code is equivalent to the 2018 IECC based on its analysis. source
• HB22-1362 was signed June 2, 2022. For jurisdictions updating a building code from July 1, 2023, it requires an energy code at least as good as the 2021 IECC plus the model electric and solar ready code, and from July 1, 2026 the model low energy and carbon code. A rural county that applied for but did not receive a state training grant may instead adopt one of the three most recent IECC editions. source
• The Colorado Energy Office says cities and counties with building codes must adopt the Model Low Energy and Carbon Code (based on the 2024 IECC with Colorado amendments), or a more stringent code, when adopting or updating any building code after July 1, 2026. Local amendments are allowed but cannot reduce efficiency. source
• HB19-1260, effective August 2, 2019, requires local jurisdictions to adopt one of the three most recent IECC editions when adopting or updating any other building code. source

Wildfire is the main state-regulated hazard for a metal or post-frame home. Colorado created a Wildfire Resiliency Code Board in 2023, and the 2025 Colorado Wildfire Resiliency Code (effective July 1, 2025) sets minimum standards for hardening structures and managing defensible space in the wildland-urban interface. Cities, counties and fire districts with jurisdiction in those areas were required to adopt and enforce codes meeting or exceeding it, so building in a mapped wildfire area can bring requirements on roofing, siding, vents, windows and vegetation clearance. The state publishes a map for checking a parcel. This research did not find an official state source on ground snow loads, frost depth or high-altitude design values; those are set locally by each building department, so ask the county for the design snow load, wind speed and frost depth for the exact site.

• Senate Bill 23-166 (signed May 12, 2023) created the Wildfire Resiliency Code Board in the Division of Fire Prevention and Control to adopt codes and standards for the wildland-urban interface. source
• The 2025 Colorado Wildfire Resiliency Code was established July 1, 2025 (8 CCR 1507-39); it sets minimum standards for hardening structures and reducing fire risk in the defensible space around them in the wildland-urban interface. The board also directed a 2025 Colorado Wildfire Resiliency Code Map. source
• SB25-142 (signed June 3, 2025) gave local governments in the wildland-urban interface nine months, instead of three, after the board adopts its codes to adopt matching or stricter local codes, and allows cooperative enforcement agreements. source
• A 2026 bill to push the local adoption deadline from April 1, 2026 to April 1, 2027 (HB26-1334) was postponed indefinitely in committee on April 7, 2026 and is listed as lost. source
• The state's hazard-planning guidance explains that a wildland-urban interface code typically covers building materials (roof, eaves, vents, gutters, walls, windows), vegetation management, emergency vehicle access, water supply and fire protection, and that each jurisdiction decides where its code applies. source

Property tax

Colorado land can be taxed as agricultural if it meets one of five tests, most commonly being used as a farm or ranch for the previous two years with a profit purpose, and having been agricultural or eligible in the prior 10 years. Land under a residence stays agricultural only if the occupant takes part in the farm or ranch operation (or is a specified relative of someone who does). A home that is not integral to an agricultural operation is classified as residential, including up to two acres around it, and taxed at the residential rate, while the rest of the land can stay agricultural. Buildings are valued separately from the land. The county assessor makes the classification decision. Colorado's main home-related property tax relief is a senior exemption for people 65 and over who have owned and lived in the home for 10 years (up to 50% of the first $200,000 of value), plus programs for disabled veterans and senior primary residence classification.

• The state Division of Property Taxation says land must meet one of five requirements for agricultural classification; the first is land used the previous two years and presently as a farm or ranch (or being restored through conservation practices) that was agricultural or eligible during the preceding 10 years. source
• Agricultural land includes land underlying a residence if the occupant participates in the agricultural operation or is a statutorily specified relative of a participant; residential land includes two acres or less on which a home sits that is not integral to the agricultural operation. source
• Real property improvements such as buildings and fences are valued separately from the land, and agricultural structures used as an ancillary part of the operation are valued under the three approaches to value. The residence is assessed by multiplying its actual value by the residential assessment rate. source
• The assessor may request an on-site inspection or documents such as the prior year's federal farm income form, grazing leases or an agricultural land classification questionnaire. Questions go to the Division at 303-864-7777 or the county assessor. source
• Seniors 65 and over who have owned and occupied their primary residence for at least 10 consecutive years before January 1 can exempt up to 50% of the first $200,000 of the home's actual value; applications go to the county assessor between January 1 and July 15. source
• A senior primary residence classification is available to owners who received the senior exemption at a previous home in 2020 or later and cannot currently receive it; applications are due to the county assessor by March 15 (late deadline July 15). source

Insurance

Colorado's Division of Insurance describes homeowners insurance as a pressure point, with affordability and availability problems especially tied to wildfire and hail, and publishes a toolkit, disaster guidance and a buyer's guide. Colorado created a FAIR Plan in 2023 (HB23-1288) as an insurer of last resort: homeowner policies became available April 10, 2025. The FAIR Plan offers limited property coverage, requires three declinations from standard insurers and a licensed agent, and is funded by assessments on insurers. New rules under HB25-1182 apply to insurers using wildfire risk scores: they must consider verified mitigation work, tell applicants and renewing policyholders their score in writing starting October 1, 2026, and allow appeals. They do not apply to surplus lines insurers. Official state guidance does not single out metal or post-frame homes, so ask insurers directly about construction type and roofing.

• HB23-1288 established the Colorado FAIR Plan and was signed May 12, 2023; residential homeowners policies became available April 10, 2025 and commercial property policies June 17, 2025. source
• The FAIR Plan offers limited property coverage when standard coverage is unavailable; applicants need three declinations from standard insurers and must work with a licensed agent. It is a not-for-profit funded by assessments on insurers, not public money. source
• Under HB25-1182, insurers and the FAIR Plan that use wildfire risk scores must credit qualified mitigation, send written score notices (to applicants within 15 days of a completed application and to existing policyholders at renewal, beginning October 1, 2026), and review appeals with mitigation evidence within 30 days. The rules do not apply to non-admitted or surplus lines insurers. source
• The Division of Insurance publishes a homeowners insurance page with a toolkit, wildfire and disaster guidance, hail storm FAQs, a buyer's guide and a premium comparison tool. source