New Jersey HVAC permit requirements

IRC/2024. New Jersey adopts one code for the whole state, so this answer does not change from town to town: ‘the Commissioner hereby adopts the model code of the International Code Council, 2024 International Residential Code known as the IRC/2024 as the one- and two-family dwelling subcode in New Jersey, subject to the modifications stated at (c) below’. It ‘may be known and cited as the one- and two-family dwelling subcode’.

IECC/2024. ‘The Commissioner hereby adopts the model code of the International Code Council, known as the International Energy Conservation Code/2024 (IECC/2024), as the energy subcode for New Jersey’.

IMC/2024. ‘The International Mechanical Code/2024 may be known and cited as the “mechanical subcode”’. For one- and two-family dwellings the heating and cooling provisions you will be reviewed against live in Chapter 14 of the IRC/2024.

Required — through the adopted code, not by name. Searching the whole of N.J.A.C. 5:23 Subchapter 3 returns no instance of “Manual J”, “Manual S” or “ACCA”. New Jersey does not restate the sizing rule; it adopts the IRC/2024 and the requirement rides in with it, at Chapter 14, Heating and Cooling Equipment (M1401).

That is worth knowing before you argue with a reviewer: the authority they are working from is the model code New Jersey adopted, not a New Jersey-written sizing rule.

In New Jersey’s subcode-assignment table, M1401.1 through M1401.3 — the heating and cooling equipment sizing sections — are assigned to the Plumbing subcode, not the mechanical one. Out-of-state contractors routinely send load calculations to the wrong official because of this.

A changeout is inspected work. The rule gives it to the mechanical inspector, who ‘shall have the responsibility for enforcement of the provisions of the code for the installation and replacement of heating or cooling equipment or water heaters or other mechanical equipment, such as refrigeration, air conditioning, or ventilating apparatus, gas piping or heating systems, or stand-by power generators’.

Where a town has not assigned one, it falls to plumbing: ‘A plumbing subcode official or plumbing inspector need not be a mechanical inspector to perform these inspections’.

Not verified. No New Jersey regulation we could find names Manual D. Duct requirements come from the adopted IRC/2024 and IECC/2024 rather than from a state-written rule.

This is the part that catches people. The code is uniform statewide, but New Jersey has no county building departments — the construction permit is issued and inspected by the municipality, each with its own construction official, submission process and queue. The technical answer is the same in every town; the paperwork and the wait are not.

The Uniform Construction Code amendments at R.2025 d.093 were filed 21 July 2025 and carry an ‘Effective Date: August 18, 2025’. If your reviewer is working from an older subcode edition, that is the rule adoption to point at.