The tension between "cats deserve outdoor access" and "outdoor cats have dramatically shorter lifespans" has a practical middle ground: enclosed outdoor space, commonly called a catio, that gives real sensory enrichment without exposing a cat to traffic, predators, disease from other cats, and parasites at anywhere near the same rate.
Why this matters more than it might seem
Outdoor, free-roaming cats have meaningfully shorter average lifespans than indoor cats, largely driven by vehicular trauma, fighting-related injuries and disease transmission (including FIV and FeLV), and predation risk. A catio sidesteps essentially all of this while still giving fresh air, sunlight, grass, birds and insects to watch, and a much larger sensory world than an indoor-only environment provides.
Sizing and placement
Even a small catio — a window box a few feet deep — provides real benefit over none at all. Larger setups connected to a window or cat door give more use, but size matters less than you'd think; consistent daily access to a small enclosed space beats occasional access to a large one. South- or east-facing placement (morning sun without full afternoon heat) tends to get the most use.
Materials and containment
Use a welded wire mesh with openings no larger than 1 inch, since cats can push through or get a paw stuck in larger gaps — chicken wire is not secure enough on its own. Wooden or metal frame construction both work; the key failure points to check are the roof (cats climb, and an open-top enclosure isn't actually secure) and any gap where the enclosure meets the house wall.
What to put inside
Vertical space (shelves, a cat tree, a ramp) gets more use than flat floor space alone. Include at least partial shade and a weatherproof shelter option, since a catio in direct sun with no shade becomes unusable in summer heat. Cat-safe grass (cat grass or wheatgrass, not lawn treated with pesticide) gives a genuine, popular enrichment item that's hard to replicate indoors.
Connecting it to the house
A cat door or tunnel from a window is the most common connection method, allowing the cat to come and go on their own schedule rather than needing supervised access. If a cat door isn't feasible, scheduled supervised access still provides meaningful benefit, though a self-directed option tends to get used more consistently over time.
A genuinely underrated option for apartment cats
Even renters without yard access can often install a window-mounted catio box that doesn't require permanent structural changes — worth checking with a landlord before assuming outdoor access isn't possible in an apartment.