Air rights in property law are your ownership of the usable airspace above your land. If you own a parcel, you generally control the vertical space above it and can build into that space, sell it, lease it, or stop others from intruding on it. That control is not unlimited. It stops where federal navigable airspace begins, and it bends to local zoning and building codes on the way up.
What Air Rights Are
The old common law rule ran “up to the heavens.” The U.S. Supreme Court retired that idea in 1946 in United States v. Causby, a case about military aircraft flying so low over a chicken farm that they destroyed the farmer’s livelihood. The Court called the unlimited upward rule one that “has no place in the modern world” and held that airspace above the minimum safe flight altitude is a public highway. In the same breath the Court said a landowner “must have exclusive control of the immediate reaches of the enveloping atmosphere” above the land. Without that control, you couldn’t build a structure, plant a tree, or put up a fence.1Justia. United States v. Causby, 328 U.S. 256
That is the line still drawn today. You own the airspace you can reasonably use and occupy above your land. Above that, starting at the minimum safe flight altitude, airspace is public.
What You Can Do With Your Air Rights
The most visible use is vertical development. When an owner builds a skyscraper, they are exercising the air rights over their parcel. In dense cities, developers routinely build above rail yards and highways because the air rights over those corridors can be bought or leased separately from the ground below.
Air rights also let you stop intrusions into your vertical space. A neighbor’s structure that hangs over your property line is a trespass at common law, and you can demand its removal. The same idea applies to tree limbs: in most jurisdictions you can trim branches that cross the property line back to that line, though you generally can’t damage the health of the tree. The Causby Court pointed to this protective function directly, noting that control of the immediate atmosphere is what makes it possible to erect buildings and plant trees in the first place.1Justia. United States v. Causby, 328 U.S. 256
What you cannot do is claim unlimited control. Your air rights are bounded above by federal airspace rules, on all sides by zoning and building codes, and sometimes by utility easements that let power companies run lines through a defined corridor overhead.
Selling or Leasing Air Rights
Air rights can be separated from the land and transferred. An owner who hasn’t built to the maximum height allowed by local zoning has unused development capacity, and that capacity has value.
Transferable Development Rights
The most structured way to transfer air rights is through Transferable Development Rights programs, usually called TDRs. Under a TDR program, an owner in a designated “sending area” gives up the right to develop and receives credits in return. Those credits are then sold to a buyer in a designated “receiving area,” who uses them to build at greater height or density than base zoning would allow. Price is set by the market.
TDRs are typically used to preserve environmentally sensitive land, historic buildings, and open space, while directing growth to areas the municipality has decided can absorb it. The idea gained national prominence after the Supreme Court’s 1978 decision in Penn Central Transportation Co. v. New York City, which involved air rights above Grand Central Terminal. New York’s landmarks law barred Penn Central from building a skyscraper on top of the terminal, and the company argued this was an unconstitutional taking of its air rights. The Court disagreed, in part because the city had granted Penn Central transferable development rights usable on nearby parcels.2Justia. Penn Central Transportation Co. v. New York City, 438 U.S. 104
Direct Sales and Leases
Outside formal TDR programs, air rights are sold or leased directly between private parties. A developer might buy air rights from an adjacent owner to construct a wider or taller building than their own lot’s zoning allows on its own. These deals need careful documentation. The deed or agreement must clearly describe the vertical boundaries being conveyed, and the transaction typically has to be recorded with the county like any other property transfer. Many jurisdictions require a survey defining the three-dimensional space being separated from the underlying parcel. Costs vary widely with location and complexity.
Zoning and FAR Limits
Owning air rights does not mean you can build whatever you want. Local zoning codes set the most immediate limits on vertical space, controlling building height, setbacks from property lines, and overall density.
One key tool is the Floor Area Ratio, or FAR. FAR caps the total floor area of a building relative to the size of the lot. A FAR of 5.0 on a 10,000-square-foot lot means you can build up to 50,000 square feet of total floor space, distributed across whatever number of stories you choose, subject to height limits. If you’ve only built 30,000 square feet, the remaining 20,000 square feet of unused FAR is essentially your untapped air rights, and it is the capacity that can potentially be transferred or sold. Advertised FAR numbers don’t always tell the whole story. Height limits, parking requirements, and other rules can prevent an owner from actually building to the theoretical maximum.
Zoning varies enormously across jurisdictions, and what’s permitted in one city may be prohibited a few miles away. Before buying air rights or planning a vertical expansion, check the specific zoning code and any overlay districts that apply to the parcel.
Federal Airspace Rules
Federal law sets a separate ceiling on private air rights. Under 49 U.S.C. ยง 40103, the United States holds “exclusive sovereignty” over all airspace in the country, and every citizen has a “public right of transit” through navigable airspace. The FAA sets policy and assigns airspace use.3Office of the Law Revision Counsel. 49 U.S. Code 40103 – Sovereignty and Use of Airspace
As a practical matter, aircraft flying within navigable airspace are not trespassing on your property, even when they pass directly overhead. Your private air rights effectively end where navigable airspace begins.
If you plan to build a tall structure, the FAA has its own notification requirements that sit on top of local building codes. Any construction or alteration exceeding 200 feet above ground level requires advance notice to the FAA. Near airports, that threshold drops significantly based on proximity and runway configuration.4eCFR. 14 CFR 77.9 – Construction or Alteration Requiring Notice
Drones Over Your Property
Drones sit in a legal gray zone. Under FAA rules, commercial and recreational drones generally cannot fly higher than 400 feet above ground level.5eCFR. 14 CFR 107.51 – Operating Limitations for Small Unmanned Aircraft That places most drone flights squarely inside the “immediate reaches” the Supreme Court said a landowner controls. Yet no federal statute explicitly makes low-altitude drone flight over private property a trespass.
The disconnect is obvious. A drone hovering at 50 feet above your backyard is well below navigable airspace and within the zone Causby said you control, but federal drone rules focus on aviation safety, not private property rights. A handful of states have begun treating drone flights below a certain altitude over private property as trespass, though the law remains unsettled in most of the country. If a drone is persistently flying low over your land and interfering with your use of it, the Causby framework offers the strongest existing legal theory, but there is no bright-line rule yet.
When the Government Restricts Your Air Rights
Because air rights are a recognized property interest, the government cannot destroy their value without consequence. The Fifth Amendment requires just compensation when it takes private property, and that includes air rights.
The clearest example is Causby. The Supreme Court held that military overflights so frequent they destroyed the farm’s usefulness as a chicken farm amounted to a taking, even though the government never physically occupied the ground. A later case, Griggs v. Allegheny County, extended the same principle to civilian airports: when low-altitude flights on takeoffs and landings made nearby land unfit for its existing use, the airport operator owed compensation.1Justia. United States v. Causby, 328 U.S. 256
Regulatory restrictions are a harder case. In Penn Central, the Supreme Court ruled that New York’s landmarks law barring construction above Grand Central Terminal was not a taking, even though it effectively eliminated substantial air rights value. The Court reasoned the restriction did not interfere with the terminal’s existing profitable use, did not prevent a reasonable return on the company’s investment, and the city’s TDR program helped offset the burden. A government restriction that only limits how much you can develop your air rights is usually not a taking. One that destroys the economic viability of the property might be.2Justia. Penn Central Transportation Co. v. New York City, 438 U.S. 104
If you believe a government action has effectively taken your air rights without payment, the legal path is called inverse condemnation. Instead of the government initiating an eminent domain proceeding, you file suit against the government to recover the value of what was taken. These cases are fact-intensive, expensive to litigate, and turn heavily on whether the restriction leaves any reasonable economic use of the affected property.
How Air Rights Are Valued
There is no single formula. Appraisers use the same three methods applied to other real estate: comparable sales, income capitalization, and cost analysis. The most common approach starts with the value of comparable land in the area and adjusts for the added costs and constraints of building in vertical space rather than on the ground. A developer building above an active rail line faces engineering and construction expenses a ground-level project would not, and those costs reduce what the air rights are worth.
For income-producing developments, appraisers often prefer income capitalization: project the revenue the finished project will generate, then work backward to what the development rights are worth after construction costs, financing, and the developer’s required return. In dense urban markets where buildable land is scarce, air rights can sell for a substantial fraction of comparable ground-level land value. In less constrained areas, they may be worth relatively little because easier and cheaper alternatives exist.
The Penn Central decision added another wrinkle. The Supreme Court acknowledged that TDRs used to offset the burden of a landmark designation had real value, but stopped short of saying they would amount to “just compensation” if a taking had occurred. In practice, the market price of transferable development rights depends on demand in the receiving area and the specific rules of the local program.2Justia. Penn Central Transportation Co. v. New York City, 438 U.S. 104