Rental fees for thin air are adding more than $100,000 a year to Wellington city's coffers.
Wellington apartment and commercial building owners who have balconies or building features jutting over city streets and footpaths are being charged for the right to occupy the airspace, Wellington City Council figures show.
Under council policy, airspace encroachments occur when a building has a "balcony, facade, dwelling, conservatory or eaves that encroaches into airspace above legal road".
Records show there are 519 airspace encroachments in Wellington, of which 467 are by apartment balconies.
The council receives $109,674 a year from airspace rentals, more than half of which comes from commercial buildings with larger encroachments from features such as balconies and some shop canopies.
But apartment dwellers are also being charged for balconies, at an average of $90.
Councillor Helene Ritchie is among those charged an encroachment fee and, as a result, she does not take part in council decisions on the fees.
While unconcerned by her annual charge of about $100 a year, she said it was amusing when you looked at the size of her encroachment - about 30 centimetres.
"It's basically a window," she said.
She also questioned the need for the bureaucracy behind the fee. "Somebody has obviously decided it's worth it."
Council spokesman Clayton Anderson said it was the developer's choice to make a building protrude into council space.
"Anyone that builds on to someone else's property is encroaching. Developers . . . in most cases choose to maximise their investment by encroaching over council's road airspace."
Built environment portfolio leader Iona Pannett said that, while balconies were arguably a benefit to the city, by providing outdoor space for inner-city dwellers and making buildings more aesthetically pleasing, they amounted to the privatisation of public space.
While the air might not be in specific use, it was also important to maintain "view shafts" that were of value to Wellingtonians.
"It [the airspace] belongs to everyone, and I'm quite a staunch defender of making sure that people aren't excluded . . . Airspace is a natural public good."
Transport portfolio leader Andy Foster said a discussion might be needed about some balconies that provided public good, but developers could have chosen to include balconies within their own boundaries, rather than infringing on council land.
Property owners are also charged for road encroachments on structures such as decks and car pads that are built on council-designated land.
About $1.4m is collected from all encroachment fees every year.
Buildings or structures that infringe on, over or under council-owned road reserve for private purposes need an encroachment licence.
Car decks, car ports or car pads
Gates and fences
Covered access ways
Porches or decks
Underground car parks or foundations
Annual fees are charged at $14.11/sqm.
Nearly 6000 Wellingtonians pay for encroachments.