Larimer County’s 2024 Building Codes Went Into Effect This Year: Here’s What You Need to Know
On September 22, 2025, the Larimer County Board of County Commissioners adopted an updated set of building codes and local amendments that will apply to permits initiated on or after January 1, 2026. These updates replace the County’s 2021 code editions effective that same date.
At J Allen Construction Company, we’ve reviewed the adoption resolution and the County’s published guidance so homeowners, designers, and builders can understand what is changing and how it may affect planning, permitting, and project scope as 2026 approaches. Note, this blog is for informational purposes only; your project is unique and you may need to speak with the Colorado Energy Office for specifics about your case.
What Has Changed: The 2024 I-Codes Become the Baseline (Starting January 1, 2026)
Larimer County is adopting the 2024 editions of the core International Code Council “I-Codes” (with local amendments), effective January 1, 2026, and repealing the previously adopted 2021 editions effective the same day.
The adopted 2024 code set includes:
- 2024 International Building Code (IBC)
- 2024 International Residential Code (IRC)
- 2024 International Energy Conservation Code (IECC)
- 2024 International Existing Building Code (IEBC)
- 2024 International Mechanical Code (IMC)
- 2024 International Plumbing Code (IPC)
- 2024 International Fuel Gas Code (IFGC)
- 2024 International Property Maintenance Code (IPMC)
- 2024 International Swimming Pool and Spa Code (ISPSC)
The County is also continuing to reference the 2023 National Electrical Code (NEC) in its published list of codes for 2026 permits.
Why This Matters for Northern Colorado Homeowners and Builders
1) A newer code cycle is being adopted, but the resolution does not list every technical change
Larimer County’s resolution explains the “I-Codes” are updated on a three-year cycle and are intended to reflect the most current building science and consensus process.
What it does not do is itemize every requirement that changed between 2021 and 2024. So the safest way to think about this is: the baseline rulebook is updating, and depending on your project, you may see differences in plan review expectations, documentation, and prescriptive requirements compared to the 2021 editions.
2) Colorado’s Electric Ready and Solar Ready Code is included (and it is a state-required adoption)
Larimer County’s adoption package includes the Colorado Electric Ready and Solar Ready Code, and the resolution notes this is a state-produced code that local governments must adopt when adopting other building codes.
What homeowners should take from that is simple: many new builds (and some major projects) may need to be designed with “future readiness” in mind, even if you are not installing solar or fully electrifying on day one. Exactly what that means for your plans depends on the building type and the specific provisions Larimer is enforcing through its adopted amendments and permitting workflows.
3) Larimer County is adopting the 2025 Colorado Wildfire Resiliency Code (not a 2024 edition)
This is a key detail. Larimer County’s public Building Codes page identifies this as the “2025 Wildfire Resiliency Code” with Larimer County amendments, effective January 1, 2026, and adopted on September 22, 2025.
So while the I-Code suite is the 2024 editions, the wildfire standard being adopted alongside them is explicitly the 2025 Wildfire Resiliency Code document.
Wildfire Resiliency: What Homeowners Should Understand (And Where People Get This Wrong)
A common misconception is that wildfire code requirements “only apply to brand-new homes.” The Larimer-adopted Wildfire Resiliency Code includes provisions that can apply to existing buildings when specific thresholds are met.
For example, it states:
- Roof coverings: if a roof covering is replaced or if
25% or more of the roof surface area is replaced, the code can require the
entire roof covering to be replaced to the new-construction standard (with noted exceptions).
- Exterior walls: if
25% or more of the total exterior wall surface area is replaced (or if the work effectively replaces the exterior wall material), the code can require the
entire exterior wall surface area and certain near-structure zone conditions to comply (with noted exceptions).
- It also includes language clarifying that provisions that specifically apply to existing conditions can be retroactive.
How This Affects Remodels and Additions
If you’re planning a remodel or addition, the key trigger is the County’s timing language: the adopted 2024 codes apply to permits initiated on or after January 1, 2026.
In practice, that means:
- Energy requirements for new or altered conditioned space will be reviewed under the 2024 IECC framework for 2026 permits.
- Life safety and building requirements for the new work will be reviewed under the applicable 2024 code(s), depending on whether the project is residential or commercial and how it is classified.
- The
2024 International Existing Building Code (IEBC) continues to be part of Larimer County’s adopted code framework and provides updated pathways for repairs, alterations, changes of occupancy, and additions in existing buildings.
- If the property is in a designated
WUI area, wildfire-resiliency provisions may become relevant for certain additions and exterior alterations, including the “25% roof” and “25% exterior wall” triggers described above.
Final Thoughts
Larimer County’s updated code adoption is a meaningful shift because it updates the baseline standards used for plan review starting January 1, 2026, and it folds in Colorado’s Electric/Solar Ready requirements and the 2025 Wildfire Resiliency Code (with county amendments).
For project-specific guidance, consult the Larimer County Building Division resources and your design professionals so you can align your plans with the standards that will govern your permit review in 2026.
Of course, you can always hire us, and we’ll just handle all this for you! Get in touch with us for your next Northern Colorado addition, renovation, or home maintenance project.











