On December 4, 2025, the Fair Haven Zoning Board heard a request to replace a rear deck with a 648-square-foot, two-story addition. The house dates to the 1920s and sits on a 7,000-square-foot corner lot in the R-5 zone. The plan would add a family room downstairs and more bedroom and closet space upstairs. The house had about 1,760 square feet of floor area. The plan would bring it to 2,418. The zone allows 2,200.
Chairman Lehder asked what would happen to the plans if the owners held to the 2,200 square feet the zone allows. The architect said it would mean substantially removing or rebuilding part of the existing house. Board members weighed adding on against tearing down. They raised the attic and cellar as space the owners could use instead, and they talked about how visible the corner was. The applicant agreed to rework the plans. The board approved a resolution for the application in April 2026.
Fair Haven puts a ceiling on how big a single-family house can be, and the ceiling depends on the zone. An addition or a rebuild usually starts with that ceiling, not with the land. For anyone buying a house to grow into, the number to learn is how much floor area the house has left under its cap.
The cap is set by zone, and past a certain lot size it stops growing
Fair Haven's Schedule of Area, Yard and Building Requirements gives each residential zone two limits. One is a floor area ratio. The other is a fixed maximum in square feet. The schedule says a single-family house may have "the lesser of the maximum floor area or the maximum floor area as calculated by applying the maximum floor area ratio to the lot area."
So the ratio controls on small lots. Once a lot passes a certain size, the fixed number takes over, and more land adds nothing to the house you can build. The table below takes the borough's ratios and maximums and works out where that switch happens in each zone.
| Zone | Floor area ratio | Fixed maximum | Floor area at the zone's minimum interior lot | Lot size where the fixed maximum takes over |
|---|---|---|---|---|
| R-40 | 0.15 | 6,900 sq ft | 6,000 sq ft on 40,000 | 46,000 sq ft |
| R-30 | 0.15 | 5,180 sq ft | 4,500 sq ft on 30,000 | about 34,500 sq ft |
| R-20 | 0.18 | 4,140 sq ft | 3,600 sq ft on 20,000 | 23,000 sq ft |
| R-15 | 0.20 | 3,450 sq ft | 3,000 sq ft on 15,000 | 17,250 sq ft |
| R-10A, R-10B, R-10 | 0.28 | 3,220 sq ft | 2,800 sq ft on 10,000 | 11,500 sq ft |
| R-7.5 | 0.35 | 3,020 sq ft | 2,625 sq ft on 7,500 | about 8,630 sq ft |
| R-5 | 0.40 | 2,200 sq ft | 2,000 sq ft on 5,000 | 5,500 sq ft |
The R-10 zones show this most plainly. A 10,000-square-foot interior lot supports 2,800 square feet. At 11,500 square feet, the minimum for a corner lot in those zones, the ratio reaches the fixed 3,220 and stops. A 14,000- or 20,000-square-foot lot in R-10A has the same limit. When you compare two listings in the same zone, the bigger lot buys a bigger yard, more room between houses and more privacy. It does not buy more house.
Look at the bottom of the table too. Moving down one zone often matters more than adding land. An R-5 lot tops out at 2,200 square feet. An R-7.5 lot can reach 3,020. When two homes look alike, the zone line between them may be the biggest difference in what each can become.
What the cap counts, and what it leaves out
The board's comment about attic and cellar space points to the second half of the rule. The code's definition of "floor area" counts the gross area of every story, measured from the outside face of the exterior walls. Stairwell openings and vaulted ceilings count too, so a two-story foyer uses up allowance on both levels.
For residential buildings, the definition leaves out:
- Any area where the height from the floor to the bottom of the roof rafters is under 30 inches
- Attics that qualify as a half story
- Cellars
- The first floor of garages
- Unfinished storage directly above a garage's first floor, if it can't be reached from a second story and the garage ridge is under 20 feet above average existing grade
Each of those has a threshold. An attic counts as a half story if it has no approved stairway, or if it has one but the part that is at least 7 feet high covers no more than one-third of the floor below. Past one-third, it counts as a full story and its floor area counts. A cellar's finished floor sits no more than 30 inches above grade. A partly underground space whose floor sits higher than that is defined as a basement and counted as a half story.
One sentence added in 2023 closes the obvious workaround. Any space "where a second story could be constructed to create areas that would qualify as Floor Area" counts "regardless of how actually constructed." Building a tall, empty volume now and finishing it later doesn't avoid the cap.
So a house at its cap can still have more usable space than its zoning number suggests. The extra comes from a finished cellar, an attic under the one-third threshold, or a garage. In Fair Haven, an ordinary renovation question, like whether a stair can reach the attic or how deep the cellar is, also decides how much room an owner has left to add.
The grade line comes before the design
The 2023 revisions also changed where a house starts. Height is measured from "Average Existing Grade," which comes from a survey or plot plan done before any demolition or construction. It uses existing elevations at a minimum of four corners of the existing structures or the proposed building location. New construction, and any renovation or addition that changes the finished-floor elevation, can't put the first floor more than 30 inches above that grade. The height and elevation rules in §30-7.11 cap principal buildings at 32 feet and 2.5 stories in R-15 and the R-10 zones, 35 feet in R-20 through R-40, and 30 feet in R-7.5 and R-5.
That 30-inch limit is tied to the cellar rule. Keep the first floor low and the space below can stay a cellar outside the floor area count. Raise it and the space below can become a basement, which the code counts as a half story. Coverage limits sit on top of all this. In R-10A, buildings, driveways and other surfaces together can cover up to 40% of the lot, and the principal building up to 35%.
Ordinance 2023-02, adopted April 17, 2023, gives its purpose as preserving the character of established neighborhoods. It says the borough reviewed recent infill trends to see that modern houses fit in with the existing ones. Its preamble traces the work to a Land Use Committee the Borough Council reconstituted in summer 2021, and to a Planning Board subcommittee that recommended the revisions.
When floor area is the last variance left
In recent cases, a plan that went over the cap went to the Zoning Board as a variance request. That meant a public hearing with engineering review letters, revised plans and often more than one meeting. Two cases recorded in the board's June 4, 2026 minutes show how this plays out at very different sizes.
At a River Road home in R-10A, the owners proposed a garage extension, a small first-floor office nook, two second-floor bathrooms and a covered rear patio. After revisions moved the patio to sit off the kitchen and removed a setback variance, the only variance left was maximum floor area. The board approved it with conditions. One condition is that the patio stay open and unenclosed. A bathroom addition, in other words, went through the same hearing process as a new house.
A riverfront property in one of the R-10 zones shows the cap at its most extreme. It covers 3.284 acres, about 1.5 of them upland, and had a house built in 1993, before the floor-area cap ordinance. The plan was to demolish it and build a new house of 5,969 square feet against the 3,220 cap, along with height, setback, garage and driveway variances. The application was carried from May 7 to June 4. In between, the applicant submitted revised plans that changed the house's orientation, its distance from the house to the north and its impervious coverage, and dropped or reduced several variances. The board approved a 5,948-square-foot version by a 6–1 vote.
That's an acre and a half of usable land in a zone whose fixed limit is the same as on an 11,500-square-foot lot. Building more meant a variance and two hearings.
Five things to find out before you make an offer
If you're buying with plans to add on or rebuild, the cap changes what you need to know during attorney review and due diligence, not afterward.
- The zone. It sets the ratio, the fixed maximum, the height limit and the coverage limits, and it can matter more than the lot size.
- The lot area from a survey. Below the switch point, every square foot of land adds to the allowance. Above it, the land adds nothing.
- The existing floor area, measured the way the code measures it. Listing square footage and zoning floor area are calculated differently. Stairwell openings and vaulted ceilings count. Cellars and qualifying attics don't.
- The space left under the cap. The December 2025 addition plan was 218 square feet over the R-5 limit, and that was enough to send it to the board.
- The attic stair and the cellar floor height. These decide whether the space you already own counts against the cap or adds to the house without touching it.
This is general information about how the borough's code is written. It is not legal, zoning or financial advice. Confirm how the rules apply to a specific property with the Fair Haven zoning officer, your attorney and your architect.
Short answers
Does the cap apply to additions or only to new houses? Both. The December 2025 and June 2026 addition cases described above involved existing homes, and each needed a floor-area variance.
Does a large lot qualify for a higher limit? Not within its own zone. The fixed maximum caps the ratio, which is why a 3.284-acre property in an R-10 zone was held to the same 3,220-square-foot limit as a corner lot of the zone's minimum size.
If you're weighing a Fair Haven house you plan to expand, or a lot you plan to build on, I'm glad to go through the zone, the survey and the remaining floor area with you, together with your architect and attorney, before you commit to a price. Katie Gay NJ. Let's Connect.
