HVAC Permit Requirements in Longmont, CO
Longmont is a city of 100,764 residents in Colorado that follows the 2021 IRC. For hvac projects, Longmont follows the IRC pretty closely, no major surprises compared to what most cities require. You're looking at roughly $70 – $225 in permit fees, plan on about 1 week for approval, plus you can apply online.
By Joey, Founder · Last verified March 29, 2026 · How we research →
When you need a HVAC permit in Longmont
Replacing an HVAC system (even same-for-same) requires a mechanical permit.
Installing a new HVAC system requires mechanical and possibly electrical permits.
Modifying or installing ductwork requires a mechanical permit.
Installing a mini-split system requires mechanical and electrical permits.
HVAC Permit Costs: Longmont vs. Nearby
Longmont comes in on the low side for Colorado. You're looking at $70 – $450 here, compared to the state average of $95 – $325.
| City | Estimated Fee |
|---|---|
| Longmont | $70 – $450 |
| Denver | $75 – $1,000 |
| Colorado Springs | $75 – $500 |
| Aurora | $70 – $900 |
Fees shown are estimates based on local building code data. Actual fees may vary based on project scope and valuation. See all Longmont permit costs →
Zoning & HOA Considerations
If you live in an HOA community: some HOAs regulate outdoor HVAC equipment placement and noise levels. Exterior condenser units, mini-split heads, and equipment pads may require screening or placement approval.
Estimated Project Timeline in Longmont
Here's a typical timeline for a hvac project in Longmont, CO:
Timeline is based on Longmont's typical about 2 weeks permit processing time. Actual timelines vary by project complexity, completeness of application, and current department workload.
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Frequently Asked Questions
Estimated permit fees for HVAC projects in Longmont, CO range from $70 – $450. Fees vary based on project scope and valuation.
It depends on the specifics of your project. Some smaller HVAC projects may be exempt from permit requirements, while larger ones typically require a permit. Use our free lookup tool to check your specific situation.
Working without a required permit in Longmont can result in fines, stop-work orders, being required to remove completed work, and complications when selling your home. It's always best to check first.
Typical approval time for HVAC permits in Longmont is about 1 week. More complex projects may take longer if plan review is required.
If you live in an HOA community, you may need architectural review approval in addition to a building permit. HOA rules and city building codes are separate, you may need to satisfy both. Review your CC&Rs and submit to your HOA's architectural review committee before starting work.
Learn More About HVAC Permits
Read our complete guide covering permit requirements, costs, common exemptions, and the application process.
Read HVAC Guide →