Glossary
Catio
A screened enclosure, often on a balcony or window, that lets a cat safely experience the outdoors from an apartment.
A catio is an enclosed, screened space, most often built onto a balcony, a window box, or a small patio, that gives an indoor cat safe access to fresh air, sun, and outdoor sights and smells without the risks of roaming free. For apartment cats especially, it is one of the few ways to add real outdoor time while still keeping the cat contained and away from traffic, other animals, or a fall risk from height.
Sizes range from a simple window-mounted box just big enough for a cat to lie in, to a larger balcony conversion with shelves and a tunnel connecting it to a window. What they share is fully enclosed mesh or netting on every open side, including above, since cats can and do jump or climb higher than owners expect.
Before adding one, check the building's rules on balcony modifications, since many leases restrict what can be attached to a railing or exterior wall, and confirm any hardware is rated for the height and weight involved. A common mistake is leaving a gap where mesh meets a window frame or railing, which is exactly where an anxious or startled cat is most likely to find an escape route.