Massachusetts HVAC permit requirements

Massachusetts is a single-code state. The residential rules are in 780 CMR, and the code says who it binds: ‘780 CMR shall be the building code for all towns, cities, state agencies or authorities in accordance with M.G.L. c. 143, §§ 93 through 100.’

The permit itself is local. The code assigns the work to the building official: ‘The building official shall receive applications, review construction documents and issue permits for the construction, reconstruction, alteration, repair, removal or demolition of a building or structure’.

10th edition, based on the 2021 I-Codes. The state handbook gives the dates: ‘The tenth edition building code became first effective on October 11, 2024 with a concurrency period, during which either the ninth or tenth edition building codes could be utilized.’ The concurrency period is over: ‘This concurrency period, which was thereafter extended, ends June 30, 2025, at which time the tenth edition will be the only building code in effect.’

For houses, the vehicle is a new chapter: ‘a new chapter 51 has been added, this chapter is entitled the Massachusetts Residential Code and adopts the 2021 International Residential Code with Massachusetts specific amendments.’ The handbook warns that the posted amendments are ‘unofficial versions’, and everything quoted here comes from them.

This is the part that changes by address. The state describes three tiers: the base code, the opt-in Stretch Code, and the opt-in Specialized Code. For the base code, the 780 CMR chapter says: ‘Buildings shall be designed and constructed in accordance with the 2021 International Energy Conservation Code (IECC) with Massachusetts Amendments contained herein.’ It then hands over to the other tier: ‘Where a municipality has adopted the Stretch energy code or Specialized opt-in energy code then 225 CMR 22.00 shall apply.’

The handbook leaves the lookup to you: ‘please consult your municipality to determine if one of these codes apply.’ The Department of Energy Resources publishes the list, described as ‘A map and list showing adoption of energy codes (Base Code, Stretch Code, Specialized Code) by all 351 Massachusetts municipalities with effective date.’ As of June 2026 it says ‘242 Municipalities have adopted Stretch Code since 2010’ and ‘60 Municipalities have adopted Specialized Code since 2023’.

From DOER: ‘The opt-in Stretch Code is IECC 2021 with key MA amendments: 225 CMR Chapter 22 (residential) and 225 CMR Chapter 23 (commercial).’ And DOER is not finished: ‘DOER is pleased to release a series of proposed revisions to the Stretch and Specialized codes, covering both commercial and residential sections.’ The page records a June 16, 2026 hearing. We did not find a final adopted version, so the proposal is not yet the rule.

The administrative chapter requires energy paperwork with the application: ‘The construction documents submitted with the application for permit shall be accompanied by completed energy code compliance documentation demonstrating’ compliance, and the sentence ends at ‘compliance with the energy provisions of 780 CMR R11.00: Energy Efficiency (as amended by Massachusetts).’

The state’s energy chapter also lists what construction documents must show. Two of the items bear on HVAC: ‘Mechanical system design criteria.’ and ‘Mechanical and service water-heating systems and equipment types, sizes and efficiencies.’ It also lists ‘Duct sealing, duct and pipe insulation and location.’

The general permit rule is broad: ‘It shall be unlawful to construct, reconstruct, alter, repair, remove or demolish a building or structure; or to change the use or occupancy of a building or structure; or to install or alter any equipment, or life safety systems for which provision is made or the installation of which is regulated by 780 CMR without first filing an application with the building official and obtaining the required permit.’

The exemption list that follows has twelve items. In a paraphrase of our reading, none of them mentions replacing heating or cooling equipment. Whether a like-for-like changeout needs a building permit, a gas or plumbing permit, or both is not verified from the state text. Ask the town. The action time is stated: ‘shall issue or deny the permit, in writing, within 30 days of filing.’

The building code adopts the mechanical code with a carve-out: ‘The installation of mechanical systems shall generally be governed by the International Mechanical Code – 2021 (“IMC”).’ But ‘this adoption shall not be deemed to apply to work governed by the Specialized Codes pursuant to M.G.L. c. 143, §96, including but not necessarily limited to sheet metal work as defined in M.G.L. c. 112, §237.’

Gas work goes to a different board: ‘Gas fired appliances are governed 248 CMR.’ The chapter ties that to ‘248 CMR: Board of State Examiners of Plumbers and Gas Fitters’.

The sheet metal statute defines its scope as ‘all commercial duct or air exhaust systems, except for refrigeration and combustion units;’ How the boards apply that to a residential duct job is not verified.

Varies — not verified as a stated state requirement. We read the Massachusetts amendments to residential Chapters R1, R11, R12 and R16 in full, and none of them writes “Manual J” or “Manual S”.

The IRC’s equipment-sizing section is M1401.3, in Chapter 14. The state posts a page for Chapter 14: Heating and Cooling Amendments, but we could not retrieve its amendment text, so we cannot say whether Massachusetts changes M1401.3. Not verified. A separate DOER draft of 225 CMR 22.00 (dated 08-29-25 and proposed, not adopted) refers to ‘heat pump space heating equipment sized in accordance with R403.7’, which is the IECC sizing section. We did not retrieve ICC’s own text of either section.

Not verified. None of the chapters we read names Manual D. They do regulate ducts: ‘Ducts shall be pressure tested in accordance with ANSI/RESNET/ICC 380 or ASTM E1554 to determine air leakage by one of the following methods:’ That is a leakage-test rule, not a duct sizing rule.