Mechanical / HVAC Permit in Flagstaff, Arizona
VerifiedRequired for heating, ventilation, air conditioning, and related mechanical installations in Flagstaff, governed by the 2018 International Mechanical Code (IMC) and International Fuel Gas Code (IFGC) as adopted by the City of Flagstaff. Minor mechanical work can use the Over-the-Counter permit; rooftop unit replacements on structures over 50 years old or in historic overlay areas are routed to Current Planning for review.
Verified 2026-07-03 · Source
When you need this permit
- Mechanical permit required for installation or relocation of furnaces, AC units, appliance vents, and similar mechanical equipment
- Governed by the 2018 IMC and 2018 IFGC as adopted by City of Flagstaff (Resolution 2019-26 / Ordinance 2019-16)
- Replacement and new rooftop units must be applied for as a full Building Permit and are routed to Current Planning for review if the structure is over 50 years old or in a historic overlay area
- Apply through the Citizen Access Portal, or use the Over-the-Counter Permit Application for qualifying minor mechanical work
Required documents
- Required
Over-the-Counter Permit Application (PDF, Rev. 06/10/2025)
Used for furnace/AC/appliance-vent replacement work not requiring a full building permit
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| Mechanical Over-the-Counter Base Fee | $29.90 | City of Flagstaff Over-the-Counter Permit Application (Rev. 06/10/2025); base fee plus itemized charges below |
| Furnace <100,000 Btu, like-for-like replacement | $18.90 | City of Flagstaff Over-the-Counter Permit Application |
| Furnace >100,000 Btu, like-for-like replacement | $23.20 | City of Flagstaff Over-the-Counter Permit Application |
| Residential Air Conditioning Unit | $13.60 | City of Flagstaff Over-the-Counter Permit Application |
| Appliance Vents | $9.25 | City of Flagstaff Over-the-Counter Permit Application |
| Vent Fan connected to single duct | $9.25 | City of Flagstaff Over-the-Counter Permit Application |
| Relocate Furnace | $18.90 | City of Flagstaff Over-the-Counter Permit Application |
| Install Suspended/Wall/Floor Mounted Heater | $18.90 | City of Flagstaff Over-the-Counter Permit Application |
| Wood/Pellet Stove/Fireplace | $18.90 | City of Flagstaff Over-the-Counter Permit Application |
Review timeline
0–0 business days
Flagstaff’s published plan-review target
Inspection process
- 1
Rough-In
Ductwork and mechanical equipment rough-in before walls closed; gas piping pressure test before concealment
- 2
Final
Equipment operational; clearances, combustion air, and venting verified
Tips
- A typical like-for-like furnace replacement under 100,000 Btu costs $29.90 base + $18.90 = $48.80 via the Over-the-Counter permit.
- Rooftop AC/HVAC unit replacements on buildings over 50 years old or in a historic overlay require a full Building Permit routed to Current Planning, not the Over-the-Counter process.
- reviewTimelineDays is 0 (no plan-review period): a qualifying Over-the-Counter mechanical permit is issued at the counter with no two-stage plan review. The City's ARS 9-835/9-836 timeframes documents (Residential Building Permits Plan Review Process and Timeframes; Commercial Plan Review) and the Over-the-Counter Permit Application itself contain no plan-review timeframe for OTC trade permits because they are not plan-reviewed. Only if the work requires a full Building Permit (e.g., a rooftop unit routed to Current Planning) is it reviewed under the 'Small Residential Plans' track (35 working days overall). Source: City of Flagstaff Over-the-Counter Permit Application (Rev. 06/10/2025) and Residential Building Permits Plan Review Process and Timeframes (PDF).
Frequently asked questions
- How much does a furnace replacement permit cost in Flagstaff?
- Via the Over-the-Counter permit process: $29.90 base fee plus $18.90 for a like-for-like furnace under 100,000 Btu (or $23.20 if over 100,000 Btu). Source: City of Flagstaff Over-the-Counter Permit Application (Rev. 06/10/2025).
Sources & verification
Verified against official sources. Last reviewed 2026-07-03.
- City of Flagstaff Building Safety Section (Planning & Development Services, Community Development Division) — official building department
- Over-the-Counter Permit Application (PDF) | City of Flagstaff
- 2019 Amendments to the Adopted Codes (PDF) | City of Flagstaff
- Residential Building Permits Plan Review Process and Timeframes (PDF) | City of Flagstaff
Fees, timelines, and adopted codes are researched from each jurisdiction's published records — see how we verify. Requirements change and vary by project, so always confirm the current details with the Flagstaff building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.
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