Rental conversions in North Jersey
Cost vs. Value's only accessory unit is a new detached cottage, priced at $192,6571 in its 2025 New York market, against $166,4062 nationally; it publishes no figure for converting a basement or attic. In New Jersey the deciding factor is local zoning, because the state has no law requiring towns to allow a second unit, so whether you can add one depends on your town's ordinance, as in Teaneck, which now permits them in some zones.
Calls are recorded. One independent company that handles rental conversions in the North Jersey area answers.
Updated October 12, 2026
The one accessory unit Cost vs. Value prices
The report's accessory unit is a new detached cottage, not a converted basement, and New York is its nearest market to Bergen County. Here it costs more to build than nationally and returns slightly less at resale.
| Measure | New York market | U.S. average |
|---|---|---|
| Accessory dwelling unit (new detached build), job cost | $192,6571 | $166,4062 |
| Accessory dwelling unit (new detached build), resale value | $67,8801 | $68,6562 |
A conversion reuses a foundation, walls and roof the cottage has to pay for, so treat this as an outside reference rather than an estimate. The code work for separating two units, further down, decides much of the real cost.
What renters pay
Census gross rent adds tenant-paid utilities to the contract rent. On that measure, Bergen County renters pay well above what Essex County renters do.
How many households rent
About a third of Bergen County's occupied homes are rented, against more than half in Essex County, where apartment buildings and multi-family houses are more common.
One house, or already two
Building-type counts show how many homes are detached and how many sit in two- to four-unit buildings. Essex has a larger share of the small multi-unit buildings.
| Measure | Bergen County | Essex County |
|---|---|---|
| Single-family detached homes | 53%5 | 33%5 |
| Homes in buildings with two to four units | 18%5 | 28%5 |
Adding a unit to a two-family house makes it a three-family building, which changes its use to Group R-2, requires its height and area to be reevaluated and can bring fire suppression requirements.6 If you already own a two-family, a third unit is a much bigger code project than a second one.
Houses built before the lead rules
New Jersey's rental lead inspections apply to units built before 1978. Census groups homes by decade, so the closest count is homes built before 1980, and that is most of the housing in both counties.
| Measure | Bergen County | Essex County |
|---|---|---|
| Homes built before 1980 | 74%7 | 74%7 |
New Jersey requires single-family, two-family and multiple rental dwellings built before 1978 to be inspected for lead-based paint hazards every three years or at tenant turnover, whichever comes first, unless the unit has a valid lead-safe certificate.8 Budget for that inspection, and for any lead hazard work it finds, before the first lease.
Permits
Zoning comes first: New Jersey leaves accessory units to each town, so the zoning office has to allow the second unit before the construction office will permit it. Under the state code, splitting a one-family house into two units is handled as a change of use, the new unit must be fire-separated from the old one, and the town issues a new certificate of occupancy. Before a tenant moves in, the town also has to certify the smoke alarms.
- New Jersey's Division of Codes and Standards has noted that some local zoning boards now approve accessory dwelling units, letting properties zoned only for one- or two-family houses add another unit.6
- New Jersey's construction code is the same statewide, with no separate local requirements; municipally employed, state-licensed construction officials and inspectors enforce it, and the owner or the owner's agent, such as the contractor, is responsible for getting the permits.9
- When a one-family detached house is converted into two units, DCA points to the Rehabilitation Subcode's change-of-use section: the house stays in the same one- and two-family code group, and the units must be separated.6
- In one- and two-family houses, work that creates an additional dwelling unit must separate the new unit from the existing one with fire partitions or horizontal assemblies.10
- Under the Rehabilitation Subcode, whenever the use of a building or part of one changes, a new certificate of occupancy is required.10
- Since January 1, 2019, New Jersey's Uniform Fire Code has required a certificate of smoke alarm compliance, issued by the town, before a one- or two-family home is sold, leased or changes occupants; the certificate is valid for six months.11
- New Jersey's code allows plumbing, electrical and HVAC work only by people licensed to do it, except a single-family homeowner working on his or her own home, and the licensed contractor's seal and signature go on the matching permit application.12
Checked October 12, 2026
Before you hire
In New Jersey, ask for the company's home improvement contractor business registration number and confirm it's active with the Division of Consumer Affairs, because registering takes proof of at least $500,00022 per occurrence in liability insurance.
Talk to a pro who handles rental conversions in North Jersey
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Your town decides whether a second unit is allowed
New Jersey's Division of Codes and Standards has noted that some local zoning boards now approve accessory dwelling units, letting properties zoned only for one- or two-family houses add another unit.6 There is no statewide rule yet. As introduced, S1786 would permit accessory dwelling units on property zoned for one- or two-family homes and have each town adopt one of two model ADU ordinances.13 A state bill on accessory dwelling units, S1786, was introduced in the Senate on January 13, 2026, reported from committee with amendments on June 1, 2026, and sent to the Senate Budget and Appropriations Committee.14
Until a law passes, the answer is in your own town's zoning ordinance. Call the zoning officer with your block and lot before paying for drawings.
One Bergen town's rules: Teaneck
Teaneck's accessory dwelling unit ordinance, added in February 2025, allows ADUs as a permitted use in the township's R-S, R-M and B-R zones.15 In Teaneck, either the ADU or the main house must be the owner's domicile, the owner files an affidavit of continued compliance every year, and the ADU can't be sold separately from the main house.15
An attached ADU in Teaneck can be up to 40 percent of the main house's floor area or 800 square feet, whichever is greater; units restricted to low- and moderate-income households can be up to 50 percent or 1,200 square feet.15 Teaneck requires one parking space for an ADU, placed in an existing driveway as tandem parking, and doesn't allow a separate outside entrance facing the street.15
A Teaneck ADU gets its own certificate of occupancy after final inspections by the construction official and the fire official, and the ordinance ties that certificate to the owner's yearly compliance affidavit.15 Other towns that adopt ordinances may set different limits, so read your own town's text.
Building the second unit
In one- and two-family houses, work that creates an additional dwelling unit must separate the new unit from the existing one with fire partitions or horizontal assemblies.10 In a basement or attic unit, ask the company exactly how the floor between the units and any shared stair will be separated, and get it on the drawings.
When an alteration creates a bedroom below the fourth floor, it needs a window or exterior door that meets the subcode's escape-opening requirements, plus a hard-wired smoke alarm in the bedroom and a second one near it.10 New Jersey's Division of Codes and Standards says finishing an existing basement is an alteration under the Rehabilitation Subcode, and nothing requires raising the existing ceiling to 7 feet just because the space is being finished.16 Ask the construction office early whether your town reads that article the same way for a separate unit.
The 2021 IRC requires at least one egress door for each dwelling unit, reached by a continuous path that does not pass through a garage, and opening to a public way or a yard or court that leads to one.17 A unit that can only be reached through the main house's kitchen won't meet that.
Rules that come with renting
New Jersey law has the landlord of a one-unit rental, or of a two-unit building the owner doesn't live in, file a certificate of registration with the municipal clerk; landlords of multiple dwellings register with DCA's Bureau of Housing Inspection.18 Every landlord must give each tenant a copy of the certificate of registration, and a copy of any amended certificate within seven days of filing it.18
Under P.L.2021, c.182, a covered rental unit's first lead inspection was due by July 22, 2024, or at tenant turnover if that came sooner, and towns must let owners hire a certified lead evaluation contractor directly.8 Where at least three percent of tested children aged six or younger have a blood lead level of five micrograms per deciliter or more, the rental lead inspection must use dust wipe sampling; elsewhere a visual inspection may be used.8 If an inspection finds lead-based paint hazards, the owner must fix them through abatement or lead hazard control, and a lead-safe certificate is good for two years.8
Since January 1, 2019, New Jersey's Uniform Fire Code has required a certificate of smoke alarm compliance, issued by the town, before a one- or two-family home is sold, leased or changes occupants; the certificate is valid for six months.11 Before a renter signs a lease for most pre-1978 housing, federal law requires the landlord to disclose known lead-based paint and hazards, share available records, hand over EPA's Protect Your Family From Lead pamphlet and include a Lead Warning Statement.19
A unit for a parent instead of a tenant
More than one in four adults 65 and older fall each year.20 Some owners build the second unit for a parent rather than a renter. A step-free path from the driveway, a curbless shower and lever handles cost little more when they're in the first drawings. NAHB's Certified Aging-in-Place Specialist (CAPS) credential trains remodelers in home modifications for aging in place.21
What happens when you call
The number on this page connects you, on a recorded line, to one independent company that handles rental conversions in the North Jersey area. The design, the schedule and the price are agreed between you and that company.
That company pays us for each call, so it costs you nothing to connect, and nobody from our side calls or texts you later. How we make money
After you're connected
Look the company up with the state before money changes hands. New Jersey's Contractors' Business Registration Act requires every home improvement contractor business, from a sole proprietorship up, to register with the Division of Consumer Affairs every year before selling or making home improvements, unless the law exempts it.22 The Division of Consumer Affairs' License Verification System is a real-time lookup; its Business Search finds home improvement contractor businesses by business name, license number or city and lists each one's registration number, license type, status and city.23 Check a New Jersey license
A New Jersey home improvement contract for more than $500, and any change to its terms, must be in writing and signed by all parties, and must list the contractor business's legal name, business address and registration number, include a copy of its liability insurance certificate with the insurer's phone number, and state the total price including any finance charges.24 Make the zoning approval a condition in the contract, so construction doesn't start before the town has said yes.
Questions people ask
Can I add an apartment to my house in North Jersey?
It depends on your town. New Jersey's Division of Codes and Standards has noted that some local zoning boards now approve accessory dwelling units, letting properties zoned only for one- or two-family houses add another unit.6 Teaneck, for example, now allows them in some zones. Teaneck's accessory dwelling unit ordinance, added in February 2025, allows ADUs as a permitted use in the township's R-S, R-M and B-R zones.15
Does converting to two units need a new certificate of occupancy?
Yes. Under the Rehabilitation Subcode, whenever the use of a building or part of one changes, a new certificate of occupancy is required.10
Do I have to register as a landlord?
If you rent out a unit, usually yes. New Jersey law has the landlord of a one-unit rental, or of a two-unit building the owner doesn't live in, file a certificate of registration with the municipal clerk; landlords of multiple dwellings register with DCA's Bureau of Housing Inspection.18
Does my rental need a lead inspection?
If the house was built before 1978, most likely. New Jersey requires single-family, two-family and multiple rental dwellings built before 1978 to be inspected for lead-based paint hazards every three years or at tenant turnover, whichever comes first, unless the unit has a valid lead-safe certificate.8
Sources
Page updated October 12, 2026. How we source our numbers
- Zonda / Journal of Light Construction, Cost vs. Value 2025, New York, NY. Released 2025. New York, NY (Cost vs. Value market). Industry source.
- Zonda / Journal of Light Construction, Cost vs. Value 2025, national. Released 2025. United States. Industry source.
- U.S. Census Bureau, American Community Survey 2020–2024 5-year, table B25064. Released January 29, 2026. Bergen County, NJ, Essex County, NJ.
- U.S. Census Bureau, American Community Survey 2020–2024 5-year, table B25003. Released January 29, 2026. Bergen County, NJ, Essex County, NJ.
- U.S. Census Bureau, American Community Survey 2020–2024 5-year, table B25024. Released January 29, 2026. Bergen County, NJ, Essex County, NJ.
- New Jersey Department of Community Affairs, Division of Codes and Standards, Construction Code Communicator, Spring 2023 ('Accessory Dwelling Units'). Released 2023. View source.
- U.S. Census Bureau, American Community Survey 2020–2024 5-year, table B25034. Released January 29, 2026. Bergen County, NJ, Essex County, NJ.
- New Jersey Department of Community Affairs, Lead-Based Paint Inspections in Rental Dwelling Units. Released March 27, 2025. View source.
- New Jersey Department of Community Affairs, Division of Codes and Standards, The New Jersey State Uniform Construction Code: General Information. Released May 2006. View source.
- New Jersey Department of Community Affairs, Division of Codes and Standards, N.J.A.C. 5:23-6, Rehabilitation Subcode. Released August 17, 2026. View source.
- New Jersey Department of Community Affairs, News release: Division of Fire Safety reminds residents to check smoke and carbon monoxide alarms. Released March 10, 2023. View source.
- New Jersey Department of Community Affairs, Division of Codes and Standards, N.J.A.C. 5:23-2, Uniform Construction Code: Administration and Enforcement. Released August 17, 2026. View source.
- New Jersey Legislature, Senate No. 1786 (2026 session), introduced text and statement. Released May 11, 2026. View source.
- New Jersey Legislature, Bill S1786 (2026-2027 session), bill history. Released June 1, 2026. View source.
- Township of Teaneck, NJ, Code of the Township of Teaneck, Chapter 33, Article IX, Accessory Dwelling Units. Released February 11, 2025. View source.
- New Jersey Department of Community Affairs, Division of Codes and Standards, Construction Code Communicator, Winter 2025 ('Ceiling Heights in Existing Homes'). Released 2025. View source.
- International Code Council, 2021 International Residential Code, Chapter 3 Building Planning. Released 2021. View source. Industry source.
- New Jersey Department of Community Affairs, Division of Codes and Standards, N.J.S.A. 46:8-28 and 46:8-29, landlord registration (DCA copy). No publication date. View source.
- U.S. Environmental Protection Agency, Real Estate Disclosures about Potential Lead Hazards. Released May 27, 2026. View source.
- Centers for Disease Control and Prevention, Facts About Older Adult Falls. Released September 4, 2026. View source.
- National Association of Home Builders, Certified Aging-in-Place Specialist (CAPS). No publication date. View source. Industry source.
- New Jersey Division of Consumer Affairs, Home Improvement Contractor Business: Frequently Asked Questions. Released March 3, 2025. View source.
- New Jersey Division of Consumer Affairs, License Verification System. No publication date. View source.
- New Jersey Legislature, P.L.2023, c.237 (Home Improvement and Home Elevation Contractor Licensing Act; amendments to the Contractors' Business Registration Act). Released January 8, 2024. View source.