Catio Ideas for Every Budget: Apartment to Backyard

The short answer

A catio is the one purchase in cat ownership that solves an outdoor problem by keeping the cat home. You can build a useful one for the price of a nice dinner (a window box), a weekend and a few hundred dollars (a walk-in from lumber and hardware cloth), or a proper backyard enclosure with a tunnel to the house for the cost of a decent holiday. Every tier works if you get three things right: hardware cloth instead of chicken wire, a fully enclosed top, and no gap wider than an inch anywhere.

This guide walks the four tiers from smallest to largest with rough costs, build time, materials, and what to check with a landlord or HOA before you start. It lives in the safety hub next to our tracker guides, and if you are here because a tracker felt like the wrong answer, you are in the right place.

Why a catio at all

Indoor cats live longer on average, and outdoor cats get fresh air, sun, and things to stalk. A catio is the compromise: outside, but enclosed. Owners consistently report that the cat uses it more than expected, that door-dashing drops because the cat now has a legitimate way out, and that the humans end up sitting in it too.

Roads, other cats, dogs, wildlife, and poisons are the main risks to an outdoor cat, and an enclosure removes all five. It also removes the need for a tracker for most cats, which we cover in do indoor cats need a GPS tracker.

Tier 1: window box and balcony mesh for renters

Window box

A window catio is a small box, usually about the size of a window air conditioner, that mounts in or against an open window. The cat steps out through the window into a mesh-walled perch with a view. Prefab versions use a frame that fits in the sash like an AC unit; DIY versions are a plywood floor, a lumber frame, and hardware cloth, supported by brackets under the sill.

Rough cost is in the range of a nice dinner out to a modest weekend away, depending on prefab versus DIY. Build time is an afternoon for prefab and a weekend for DIY. The landlord question is usually about the mounting: a unit that sits in the sash and is held by the window itself, with no screws into the frame, is often fine under a standard lease. Anything bolted to the exterior wall usually needs written permission.

For safety, the window box needs a solid floor, hardware cloth walls and top, and a gap-free fit where the box meets the window frame. That last one is where most DIY window boxes fail.

Balcony mesh

If you have a balcony, the cheaper option is to enclose it. Cat netting or, better, hardware cloth panels are fastened floor to ceiling around the open sides, and the balcony becomes the catio. Rough cost is similar to the window box; build time is a day.

The landlord and HOA questions are bigger here because the change is visible from the street. Most leases and many HOA rules forbid altering the exterior appearance. Tension-mounted panels that press between floor and ceiling without screws are the renter’s answer, and there are prefab tension systems designed for exactly this. Take photos before and after, and keep the panels removable.

Balcony gaps are the safety issue. Railings often have gaps well over an inch, and the space under the bottom rail is a classic escape route. Every gap needs mesh, anchored so a leaning cat cannot push it out. Above the second floor, the balcony is fully enclosed or not used at all.

Tier 2: the DIY 4x4 walk-in

This is the tier where most owners land, and it is the best value in the list.

What you are building

A frame of 2x2 or 2x4 lumber, roughly four feet square and six to seven feet tall, with hardware cloth stapled over every face including the top, a door with a latch, and a floor of pavers, deck boards, or just the ground. It sits against the house under a window or next to a door, and the cat gets in through a cat flap fitted to the window or wall.

Rough cost is a few hundred dollars in materials, more if you want a proper roof panel and a paved floor. Build time is a weekend for one person with a saw and a staple gun, or a long day for two. No special skills beyond measuring twice.

Materials, and why hardware cloth

Use galvanized hardware cloth with half-inch openings, 19 gauge or heavier. It is stiff, it resists claws and teeth, and the small openings keep paws in and raccoon fingers out. Chicken wire is the mistake everyone makes once: it is thin, the hexagons are big enough for a paw or a snout, it rusts, and a motivated cat can push through it. The price difference over a small catio is the cost of a takeout order.

Staple the cloth on the inside of the frame so the cat cannot lever it off, and cover the staple line with a lath strip so there are no exposed wire ends. Overlap sheets by a couple of inches and wire them together. Every edge should be covered or folded.

Untreated lumber only where the cat can chew. Pressure-treated wood is fine for ground contact posts the cat cannot reach, but for shelves, frame members at cat height, and anything a cat might gnaw, use untreated cedar or pine and seal it with a pet-safe finish or leave it bare. Cedar also resists rot without chemicals.

Shade, weather, and the top

A catio with no shade is a greenhouse by noon. Put a solid panel over at least a third of the top, either polycarbonate roofing or sloped plywood, at the end away from the afternoon sun. In hot climates, shade cloth over the whole top and a water bowl inside are not optional.

The top must be enclosed with hardware cloth, full stop. An open-topped catio is a tall fence, and cats climb fences. Owners report cats clearing six feet from a standing start on a shelf, which is why the shelves should not be within jumping distance of any gap.

For weather, a raised floor keeps the cat dry, and a covered shelf at the sheltered end gives a dry spot in rain. If it snows where you live, the roof needs to shed snow or the hardware cloth will sag under the weight.

Multi-cat sizing

Four by four is fine for one or two cats if you use the height. For three or more, go longer rather than wider, say four by eight, and add shelves at three or four levels so each cat can claim its own. Two exits matter more than floor area: a single cat flap in a multi-cat home becomes a chokepoint, and the boldest cat will sit in it. A second flap, or a flap plus a door the cat can use when you are around, prevents the standoff.

Tier 3: prefab kits

Prefab catios arrive as pre-cut panels, usually cedar frames with hardware cloth already stapled, and assemble with screws in a few hours. They come in sizes from a window box to a walk-in the size of a small shed, and the larger ones can be joined with tunnels.

Rough cost runs from a modest weekend away for a small unit to a few thousand dollars for a large walk-in with a roof and shelves. Build time is an afternoon to a day. You pay roughly double the DIY materials cost for the time saved and for panels that are square, which matters when you want a door that closes.

The trade-offs are size and fit. Prefab units come in fixed dimensions that may not match the space beside your house, and the cheaper ones use thinner mesh than we would choose. Read the spec: if it says “wire mesh” without a gauge or opening size, ask, and if the answer is anything larger than half an inch, keep looking. The better kits use proper hardware cloth and cedar and will outlast a DIY build.

Landlord and HOA considerations are the same as for a DIY walk-in. A freestanding structure under a certain size is often exempt from permit rules for sheds, but HOAs may have opinions about anything visible from the street. A prefab that sits on pavers and is not bolted to the house is the easiest to justify as removable.

DIY or prefab?

Our lean: DIY if you own the house and have a saw, prefab if you rent or if a weekend of building sounds like a punishment.

Tier 4: the full backyard enclosure with a tunnel

The top tier is a large enclosure, often eight by twelve feet or more, sited somewhere in the garden with trees or a view, connected to the house by an enclosed tunnel that runs from a cat door. The cat lets itself out, walks the tunnel, and spends the day in what is effectively a screened garden room.

Rough cost is a few thousand dollars in materials for a DIY build and considerably more for a contractor or a large prefab with tunnels, roof, and shelving. Build time is two to four weekends for a capable DIYer, or a week for a contractor. This is the tier where a permit is plausible, because the enclosure may exceed the size threshold for accessory structures in your area. Ask the local planning office before buying lumber, and check HOA covenants for anything about fencing, structures, or animals.

The tunnel

The tunnel is a long narrow catio, about a foot square in cross-section, built from the same lumber and hardware cloth as the enclosure. It runs from a cat flap in a wall, window, or door to the enclosure. Support it every few feet, roof it so rain does not pool, and check the joints at both ends for gaps. Tunnels are where escapes happen, because they have more joints per foot than anything else.

A cat flap with a microchip lock keeps the neighbor’s cat out of your tunnel, and a lockable flap lets you keep your cat in at night.

Making a big enclosure feel like outside

Put it under or beside a tree for shade and bird traffic. Include a solid roof section for rain, shelves at several levels, a scratching post, planters with cat grass, and a chair for you. Owners report that the enclosures that get used are the ones with things to watch, so face the long side toward the garden rather than the fence.

For several cats, this size handles four or five if the vertical space is used. Build staggered shelves along two walls, add a bridge or ramp between them, and give the tunnel a second entrance so there is never a single chokepoint.

Safety rules that apply to every tier

A short list, all of it learned the hard way by other owners.

• No pressure-treated lumber anywhere a cat can chew. Use it for buried posts only.
• No gap wider than one inch, anywhere: between mesh and frame, around the door, at the tunnel joints, under the bottom rail. Check with a tape measure, then check again at cat height.
• Enclose the top. Every time.
• Cover cut wire ends and staple lines with lath or trim.
• Shade at least a third of the footprint and provide water.
• No toxic plants inside or reachable through the mesh. Lilies are the big one; check any plant before it goes in.
• Bring cats in during storms, extreme heat, and overnight unless the enclosure is built for it.
• Check the mesh seasonally for rust, sag, and anything that has chewed at it from outside.

Furniture that works inside a catio

A catio is a room, and it needs furniture. Weatherproof shelves are the backbone, but a cat also wants something to scratch, something to lie in, and something that changes level.

The Hepper Hi-Lo is a scratcher lounger that doubles as a low cat tree, and its shape works well in a catio because it sits low, gives a scratching surface and a lounging surface in one footprint, and can be moved inside in winter. Keep it under the roofed section, since cardboard and fabric do not love rain. Based on owner reports, cats use it as the ground-level spot in a catio with shelves above, which is exactly what a multi-level setup needs.

Beyond that, a heavy water bowl, a bed under the roof, and a planter of cat grass finish the room. Skip anything with a cord.

Introducing cats to the catio

Most cats take to a catio within a few days, and the ones who do not are usually reacting to the cat flap rather than the enclosure. Tape the flap open for the first week so it is just a hole, then let it swing once the cat is going through freely. A covered shelf near the house end gives a nervous cat a retreat that is technically outside.

Where to go next

If you built a catio because a tracker felt like the wrong tool, do indoor cats need a GPS tracker will confirm or challenge that instinct. If your cat still has some genuinely free outdoor time, or a door gets left open more than you would like, best GPS trackers for cats explains the technologies and why weight is the deciding factor for a small cat. And Tractive Cat Mini vs AirTag settles the cheap-versus-capable question. All of it lives in the safety hub.