The dates, from the state's own notices
- October 20, 2025. The Department of Community Affairs proposes the 2024 codes (57 N.J.R. 2354(a)). Comments close December 19, 2025.
- July 15, 2026. Commissioner Jacquelyn A. Suárez adopts them (R.2026 d.086), with matching changes to the rehabilitation subcode for existing buildings (R.2026 d.087).
- August 17, 2026. Both take effect.
- February 16, 2027. The last day to file a complete application under the 2021 codes. The rule gives six months. When the state last changed codes, it adopted them on September 6, 2022 and named March 5, 2023 as the last day (DCA, Fall 2022). The same count from August 17 lands on February 16. ICC's New Jersey update lists February 17, 2027 as the day the new codes become the only option (ICC-NTA).
What moved, subcode by subcode:
- Building, one- and two-family dwelling, energy, mechanical and fuel gas: from the 2021 International Codes to the 2024 editions, with New Jersey's amendments.
- Electrical: from the 2020 National Electrical Code to the 2023 edition.
- Existing buildings: the rehabilitation subcode stays New Jersey's own, updated to point at the new editions.
Which code your project is reviewed under
The grace period is one rule, N.J.A.C. 5:23-1.6. For six months after a code change, an applicant “may submit a complete permit application, including all prior approvals,” and have it reviewed under the old code. A project already under review on the change date, with no permit issued yet, also stays on the old code.
“Complete” is the catch. Prior approvals means things like zoning: for a one- or two-family home, plan review doesn't start until zoning approval is in (N.J.A.C. 5:23-2.15). The DCA also asks that the application say which code edition the plans were drawn to.
Where that leaves your project
- Permit application already under review on August 17: it stays on the 2021 codes.
- Plans drawn to the 2021 codes, zoning approved: file the complete application by February 16, 2027.
- Still waiting on a variance or another approval: the application isn't complete until it's in. If that runs past February 16, the plans have to meet the 2024 codes.
- Starting the design now: draw it to the 2024 codes. The grace period only helps plans that already exist.
- Work inside your existing house (a basement, kitchen or bathroom): reviewed under the rehabilitation subcode, below.
The construction office in your town has the final word on the date. Ask before you count on the last week.
Additions: the energy numbers changed
The state requires energy-code compliance for a new building or an addition. A repair, renovation or alteration of an existing building only has to meet the rehabilitation subcode (DCA Bulletin 22-1). So the new insulation and window numbers land on additions.
The numbers depend on the county. Essex, Union and Hudson are zone 4A. Passaic, Bergen and Morris are zone 5A. The DCA's summary of the 2024 energy code says the insulation values that went up in 2021 went back to their 2018 levels (proposal summary):
| Part of the addition | 2021 code | 2024 code |
|---|---|---|
| Ceiling insulation | R-60 | R-49 |
| Windows, U-factor (max.) | 0.30 | No change |
| Skylights, U-factor (max.) | 0.55 | 0.53 |
| Wood-frame wall | R-30, or 20+5ci, 13+10ci, 0+20ci | No change |
| Floor over unheated space | R-19 | R-19, or 13+5ci, or 15ci |
| Basement wall | R-10ci or R-13 | No change |
| Unheated slab edge | R-10ci, 4 ft deep | R-10ci, 3 ft deep |
| Part of the addition | 2021 code | 2024 code |
|---|---|---|
| Ceiling insulation | R-60 | R-49 |
| Windows, U-factor (max.) | 0.30 | 0.28 |
| Skylights, U-factor (max.) | 0.55 | 0.50 |
| Wood-frame wall | R-30, or 20+5ci, 13+10ci, 0+20ci | No change |
| Floor over unheated space | R-30 | R-30, or 19+7.5ci, or 20ci |
| Basement wall | R-15ci, R-19 or 13+5ci | No change |
| Unheated slab edge | R-10ci, 4 ft deep | R-10ci, 3 ft deep |
“ci” is continuous insulation, the boards that run across the framing. These are the headline values from the DCA's table. Your designer works from the full code tables and their footnotes.
Lower insulation numbers don't mean a looser code. The 2024 edition adds an energy-credit requirement (10 credits, per the DCA's summary), and the DCA cites a federal estimate that the 2024 code is 8% more efficient than the 2021 one. How the credits apply to an addition is a question for the person drawing your plans.
Three more rules that touch additions
- The door from an attached garage into the house must now be self-latching and self-closing. New Jersey had struck that line from earlier editions. This time the DCA kept it, pointing to electric cars and batteries in garages, and called it “both necessary and affordable for new construction.”
- A room over a garage still needs New Jersey's one-hour fire-resistance rating for the separation and the structure that supports it, an amendment the state carried into the 2024 edition.
- No sprinklers are required in one- and two-family homes. The national code includes them; New Jersey deleted the section again.
Decks: one section, and New Jersey's stair numbers stay
- The 2024 residential code gathers the deck structure rules into one section, R507. Railings, stairs and handrails sit in R318 to R321.
- The 2024 edition added a section on attaching a deck to an existing wall. New Jersey deleted it, because work on the existing house goes through the rehabilitation subcode.
- Stairs: New Jersey still allows 8 1/4-inch risers and 9-inch treads, where the national code says 7 3/4 and 10.
- The step down from an exterior door to a deck or landing can be up to 8 1/4 inches in New Jersey, against 7 3/4 nationally.
- Handrails: 30 to 38 inches high in New Jersey. The national code starts at 34.
- Footings: the frost line is still 3 feet in Mercer, Middlesex and every county north of them.
What didn't change: every new deck needs a permit, and replacing parts in kind, in the same place, is still ordinary maintenance.
Deck prices and the full list of numbers the inspector checks
Basements and other work inside an existing house
New Jersey reviews work in existing buildings under its own rehabilitation subcode, N.J.A.C. 5:23-6. The other subcodes apply only where it says so. Its August 17 update adds one line that matters here: where it names a standard without an edition, it now means the edition in force on August 17, 2026 (5:23-6.2(c)).
- Escape windows follow bedrooms. New Jersey's edition of the 2024 residential code requires one in every sleeping room and drops the national wording that covers every basement.
- The national code's new basement sections are gone. New Jersey deleted the 2024 sections on escape openings for basement alterations and dwelling additions, and the one on habitable attics.
- Alarm upgrades come from the rehabilitation subcode, not the residential code: New Jersey deleted the residential code's alteration rules for smoke and carbon monoxide alarms.
- Like-for-like replacement: a component that already meets the current code has to be replaced with one that does.
What finishing a basement costs, with the rules for alarms, ceilings and radon
Kitchens: an island no longer needs an outlet
Under the 2023 National Electrical Code, island and peninsula countertops don't need receptacles. If you want one there, it has to be installed the way the code lays out. The DCA kept that rule over an objection, for “greater flexibility in design” ( adoption notice).
On our jobs
We file the permits for the decks, basements and additions we build, in the town where the work is. If you already have plans, tell us which code they were drawn to and whether zoning is approved. Those two answers decide whether the application can go in under the 2021 codes before February 16, 2027, or has to meet the 2024 ones.