Do I need a permit to replace my furnace in Boise?

Yes. Furnace replacements require a Mechanical Permit (422). For a single appliance replacement in an existing single-family home, the fee is $55 per Boise's Mechanical Code Fee Schedule, Table B(3).

Does gas piping work require a Mechanical or Plumbing Permit in Boise?

Mechanical Permit. Gas piping, fuel gas systems, and boilers are covered under the Mechanical/Fuel Gas permit (422) in Boise, not the Plumbing permit.

Residential Mechanical / HVAC Permit in Boise, Idaho

Required for heating, ventilation, air conditioning, fuel gas, and related mechanical installations in Boise single-family dwellings and duplexes. Covers furnaces, A/C, heat pumps, ductwork, gas fireplaces, gas piping, dryer vents, range hoods, and bath exhaust fans.

Verified 2026-06-29 · Source

When you need this permit

Install or change any part of a heating or cooling system
Furnace, air conditioner, heat pump, or boiler installation or replacement
Ductwork installation or major modification
Gas piping installation or pressure testing
Wood stoves, pellet stoves, gas fireplaces installation
Gas piping and fuel oil tank installation or modification

Required documents

Req
Mechanical Permit Application
Boise PDS mechanical permit application (MEC-PDS Application Building.pdf); available online at permits.cityofboise.org or as a PDF

Fee schedule

Fee type	Amount	Notes
New SFD / Duplex mechanical — up to 1,500 sq ft	$130 per dwelling unit	Boise Mechanical Code and Fuel Gas Code Fee Schedule, Table B(1) (Oct 2021)
New SFD / Duplex mechanical — 1,501 to 2,500 sq ft	$180 per dwelling unit	—
New SFD / Duplex mechanical — 2,501 to 3,500 sq ft	$250 per dwelling unit	—
New SFD / Duplex mechanical — 3,501 to 4,500 sq ft	$290 per dwelling unit	—
New SFD / Duplex mechanical — 4,501 sq ft or more	$325 per dwelling unit, plus $65 per each additional 1,000 sq ft over 4,501 sq ft	—
Single mechanical fixture/appliance installation (existing residence)	$55	Table B(3) — applies to single furnace, A/C, mini-split, gas fireplace, gas piping, pellet stove, woodstove, pool heater, gas fire pit, solar thermal system, etc.
Multiple fixtures — residential addition, alteration, or repair (base fee + per fixture)	$32 base, plus $12 per appliance/fixture	Table B(2) — applies to alterations involving multiple fixtures: furnaces, A/C, mini-splits, gas piping pressure tests, ductwork, dryer exhaust, bath exhaust, range hoods, etc.
Reinspection Fee	$55	—

Review timeline

~1–10 business days

Typical estimate — confirm current times with the Boise building department

Inspection process

1
Gas Piping Pressure Test
Required before concealing gas piping — verify no leaks under test pressure
2
Rough-In
Ductwork and mechanical equipment rough-in before walls closed — verify clearances and support
3
Final
Equipment operational, combustion air verified, venting correct, thermostat functional

Tips

Gas piping work (including gas fireplace hookups) requires a Mechanical Permit in Boise — not a Plumbing Permit.
Boise single-family residential mechanical work is governed by 2018 IRC Parts V and VI (not the IMC, which applies to commercial/3+ unit projects).
Like-for-like furnace and A/C replacements require a permit in Boise.
Idaho allows homeowners to perform mechanical work on their own residence; a permit and inspection are still required.

Frequently asked questions

Do I need a permit to replace my furnace in Boise?: Yes. Furnace replacements require a Mechanical Permit (422). For a single appliance replacement in an existing single-family home, the fee is $55 per Boise's Mechanical Code Fee Schedule, Table B(3).
Does gas piping work require a Mechanical or Plumbing Permit in Boise?: Mechanical Permit. Gas piping, fuel gas systems, and boilers are covered under the Mechanical/Fuel Gas permit (422) in Boise, not the Plumbing permit.

Sources & verification

Verified against official sources. Last reviewed 2026-06-29.

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 Boise building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.

Other permits in Boise

Residential Building Permit (New Construction)Residential Addition / Alteration Permit Residential Electrical Permit Residential Plumbing Permit Residential Roofing Permit Solar Photovoltaic (PV) Permit Accessory Dwelling Unit (ADU) Permit Water Heater Permit

Related guides

Furnace Replacement Commercial TI

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