Think of a catio as a room whose walls happen to be mesh. It is an enclosed outdoor space, fixed to the house or standing in the garden with a safe link back indoors, roofed and screened so completely that she cannot get out and no dog, fox or wandering cat can get in. From her side of the mesh the appeal is obvious: warm air, grass and insect smells, birds to watch at close range, and sun that moves across real ground. From your side the appeal is control, because all of that arrives without traffic, fights or a cat missing at dusk.
Sizing the Space in Her Terms
There is no official standard measurement for a catio, so treat every dimension in this section as planning guidance drawn from function, not a rule to comply with. Describe the room in her terms first. She needs room to stretch full-length on the ground without touching mesh at either end, room to scratch properly, perches at two heights so she can choose between surveying and hiding, a tray placed away from her bed and water, and shade she can retreat into at the hottest part of the day. A space that delivers those five functions is big enough; a larger space missing shade or a second perch height is not.
Translated into planning guidance, a window box suits short supervised spells, while a ground run she will use for hours each day works well at roughly two metres long by one metre deep, with enough height for two shelf levels and a person-sized door or hatch for cleaning. Go longer rather than taller if the budget forces a choice, because ground she can patrol, roll on and cross at a trot delivers more daily value than a third high shelf. Build access from inside the house where you can, through a cat flap in a wall or window panel, so she chooses her own sessions and you are not carrying her in and out like luggage.
Stocking the Catio
The stocking set is identical wherever it is listed in this article: scratching log, shelves, weatherproof bed, water and safe planting. A scratching log, a sturdy length of rough barked wood fixed so it cannot roll, gives her a scratching post that smells of the outdoors and survives weather that ruins indoor posts. Shelves at two heights, wide enough to lie on rather than merely sit, create the surveying point and the shaded lower den, and they should be fixed so a landing cat cannot shift them. A weatherproof bed, raised off ground that will get wet and placed in the corner that keeps shade longest, becomes the sleeping base she returns to.
Water belongs inside in a heavy bowl that cannot be tipped, refreshed on the same rhythm as her indoor bowl, because a catio session on a warm day is exactly when a spilled bowl matters. Safe planting finishes the set: pots or a planted strip of grasses and herbs chosen from plants recognised as safe for cats to chew, giving her something green to rub against, nibble and hide behind. Check any plant against a reliable safe list before it goes in, and keep fertilisers and slug treatments out of the enclosure entirely, since mesh keeps animals out but not chemistry.
Keeping the Enclosure Sound
A catio earns trust through boring checks. Walk the mesh weekly looking for lifted staples, rusted corners and gaps at ground level, test latches with a firm pull, and clear leaves or snow from the roof before weight builds up. In hot weather confirm the shade still falls where her bed sits, because the sun's angle shifts across the season and a bed placed in spring shade can sit in full glare later in the year. Everyone who opens the catio door needs the same closing habit, and those latch, tray and watering duties can be shared through Family Sharing, with the catio notes kept by KinsLe inside her profile for the whole household.